Antipyretic effect of oral dipyrone (Metamizole) compared to oral ibuprofen in febrile children: a systematic review and meta-analysis.

BACKGROUND: Dipyrone (Metamizole) is a potent pain reliever and fever reducer with muscle relaxant properties, most commonly used as an analgesic and antipyretic agent. Despite the fact that it has been banned in many high-income countries following confirmed studies of fatal agranulocytosis and adverse drug reactions, it is still widely used in various countries of the world. However, the antipyretic therapeutic indications of dipyrone in febrile children are currently unknown, and there is little information on the advantages and disadvantages of using dipyrone in febrile children. In febrile children, we expected that dipyrone's antipyretic effectiveness wouldn't be any more effective than ibuprofen. Therefore, the purpose of this research is to evaluate the effectiveness of oral dipyrone and oral ibuprofen as antipyretics in febrile children. METHODS: Several databases, including PubMed, Scopus, Web of Science, and Cochrane Library, were searched thoroughly using a pre-established search strategy for potential research. The studies included in this analysis comprised randomized controlled trials that compared the antipyretic effects of oral ibuprofen and oral dipyrone in febrile children. Data analysis was carried out using RevMan 5.4 software. RESULTS: Three studies were selected among the 27 publications we discovered to be applicable, and they underwent qualitative and quantitative analysis. The pooled analysis revealed no discernible difference between oral dipyrone and oral ibuprofen in terms of their antipyretic effects (Mean difference (MD) = 0.06; 95% confidence interval (CI): -0.08, 0.20). CONCLUSION: Both oral dipyrone and ibuprofen are effective in reducing high-temperature levels in febrile children without any significant difference.

Use of dipyrone during pregnancy and risk of congenital anomalies: a systematic review.

PURPOSE: This study aimed to summarize the evidence on the teratogenic effects of dipyrone used during pregnancy. METHODS: Databases (MEDLINE, EMBASE, Cochrane Library, CINAHL, Web of Science, Lilacs, SciELO, SCOPUS, OasisBR, and OpenGray) were reviewed until September 2023. We included studies that compared pregnant women who used dipyrone during any gestational period with those who used other analgesics or did not use any analgesics during the same gestational period. The outcome assessed was the presence of any congenital anomaly. Two reviewers independently conducted the review process, and a third reviewer resolved any disagreements. The risk of bias was assessed using the Joanna Briggs Institute tool for observational studies. The reviewed data synthesis is presented in narrative form. RESULTS: The search retrieved 2045 results, of which seven studies were included in the review, four were case‒control studies, and three were cohort studies involving 153,562 participants. The congenital anomalies evaluated varied across studies, with unspecified congenital anomalies predominating. Five of seven studies found no association between dipyrone and congenital anomalies. In a case‒control study, a positive association was found between dipyrone use and isolated congenital cataracts compared to two control groups; in another study, a positive association for unspecified congenital anomalies was observed in only one of the two control groups analyzed. In all studies, a high risk of bias was identified, especially regarding measuring the exposure, outcome, and assessment of confounding factors. CONCLUSION: There is not enough evidence to define the risk of congenital anomalies associated with dipyrone use during pregnancy. REGISTRATION: CRD 42022333041.

Assessing potential risk factors for metamizole-induced leukopenia.

Background: Metamizole is a non-opioid analgesic agent that can rarely cause agranulocytosis, a severe form of leukopenia. Objectives: The aim of this study was to assess previously identified potential risk factors for the development of metamizole-induced leukopenia. Design: A retrospective, observational, matched case-control study was performed in a single-center setting. Methods: Patients who developed leukopenia in the setting of metamizole therapy were included as cases and matched 1:3 on the basis of age and sex to control patients who did not develop leukopenia when treated with metamizole. The data were obtained from the medical records of patients hospitalized at Cantonal Hospital Baselland between 2015 and 2020. Univariate and multivariate analyses were performed. Results: Eighty-six cases and 258 matched controls aged between 18 and 102 years were included. Fifty-seven percent were female. Previous leukopenic episodes (odds ratio (OR): 4.02, 95% CI: 1.95-8.28, p < 0.001) and a history of penicillin allergy (OR: 2.49, 95% CI: 1.03-6.03, p = 0.044) were found to be independent risk factors for metamizole-induced leukopenia. Conclusion: A history of previous leukopenic episodes and a history of penicillin allergy were confirmed as risk factors for metamizole-induced leukopenia. In our opinion, metamizole should be avoided in patients with these risk factors.

METHOD: We compared hospitalized patients treated with metamizole who developed leukopenia, with similar hospitalized patients who did not develop this side effect. RESULTS: It was observed that patients were more likely to develop leukopenia under metamizole therapy if they: - had previous episodes of leukopenia - were under cytostatic/immunosuppressive therapy (for example drugs used to treat cancer or autoimmune conditions) - had a history of penicillin allergy. CONCLUSION: These findings will help in identifying people who are at risk of developing this serious side effect, so that they can be given a medication for pain or fever that suits them better.

Assessing potential risk factors for metamizole-induced leukopenia Background: Metamizole is a medication used to treat pain and fever. It carries a risk of developing the side effect of a low white blood cell count (leukopenia). Researchers have identified certain risk factors which predispose some, but not all, people to develop this side effect. We undertook this study to examine these risk factors in more detail.

"Eco-friendly HPLC method for analysis of dipyrone and hyoscine in different matrices with biomonitoring".

A selective, precise, and accurate reversed HPLC method has been developed and validated for simultaneous separation and determination of two veterinary drugs, dipyrone and hyoscine, in their combined dosage form in the presence of their official impurities, namely 4-aminoantipyrine and tropic acid, in addition to the formulated preservative: phenol. The linearity range was found to be (1.00-35.00 µg/mL) for dipyrone and (2.50-50.00 µg/mL) for hyoscine. It exhibited a satisfactory linearity regression R (0.9999) for both drugs with LOD 0.22 µg/mL and 0.72 µg/mL and LOQ 0.65 µg/mL and 2.19 µg/mL for dipyrone and hyoscine, respectively. Additionally, the two cited drugs were also determined in the presence of dipyrone active metabolite 4-aminoantipyrine using diclofenac as an internal standard in bovine urine. The linearity range was found to be (15-75 µg/mL) for dipyrone, (2.5-60 µg/mL) for hyoscine, and (2.5-60 µg/mL) for 4-aminoantipyrine with linearity regression R (0.9999-0.9998). The LLOQ (15, 2.5, 2.5 µg/mL), LQC (45, 7.5, 7.5 µg/mL), MQC (55, 25, 25 µg/mL), and HQC (60, 50 50 µg/mL) were determined for dipyrone, hyoscine and 4-aminoantipyrine, respectively. UV detection was carried out at 220 nm. The method was validated according to the ICH guidelines, as well as according to FDA guidelines for determining both drugs in bioanalytical matrices and both proved accuracy and precision. A statistical comparison was made between the results obtained and those obtained by the reported method, showing no significant difference in accuracy and precision at p = 0.05. The suggested method was proved eco-friendly through a greenness assessment using two different tools (The analytical eco-scale scored 83, and the AGREE-Analytical Greenness Metric approach scored 0.83). The suggested method can be used in the routine work of quality control labs, screening for drug abuse, and ensuring clean sport for horse racing.

Antinociceptive and anesthetic-sparing effects of levomethadone/fenpipramide cannot be enhanced by coadministration of metamizole in awake and anesthetized Beagles.

OBJECTIVE: To determine the effect of levomethadone/fenpipramide and metamizole alone and in combination on acute nociception. METHODS: 8 healthy, adult Beagles were used in 2 separate randomized, complete crossover, experimental trials (threshold testing and determination of minimal alveolar concentration [MAC]) with masked observers. In both trials, treatments were 0.2 mg·kg-1 levomethadone/fenpipramide (L), 75 mg·kg-1 metamizole (M), or their combination (LM). In conscious dogs, mechanical thresholds were determined using constantly rising force. Thermal thresholds were measured via ramped contact heat. The MAC of sevoflurane was determined using the bracketing method with electrical stimulus (50 V, 50 Hz, 10 ms) before and 1 and 4 hours after treatment. RESULTS: Mechanical thresholds in L and LM were significantly increased above baseline (BL) for 165 minutes and above M for 135 minutes. Percent thermal threshold excursion significantly increased above BL in L for 75 minutes and in LM for 135 minutes. In L and LM, the percent thermal threshold excursion was significantly higher than in M from 15 to 75 or 135 minutes, respectively. In L and LM, the MAC of sevoflurane was significantly reduced at 1 hour compared to BL and M. CONCLUSION: Duration but not the magnitude of thermal antinociception of levomethadone/fenpipramide was increased by metamizole. Mechanical antinociception in awake dogs and anesthetic-sparing effects of levomethadone/fenpipramide were not altered. CLINICAL RELEVANCE: Coadministration of levomethadone/fenpipramide and metamizole to increase antinociception is not justified.

Toxicological effect of acetaminophen, metamizole, and nimesulide cocktail on early development of zebrafish.

BACKGROUND: Several countries' most incorrectly discarded medicines are acetaminophen (ACM), metamizole (MTZ), and nimesulide (NMS). These xenobiotics easily reach the aquatic environment; such contamination is very important for the health of humans and other species, yet little explored. OBJECTIVES: To evaluate the cocktail effect of ACM, MTZ, and NMS during zebrafish's initial development. METHODS: Zebrafish embryos 6-8 h post-fertilization (hpf) were exposed to different concentrations of ACM, MTZ, and NMS, separately, to obtain the 50% lethal concentrations (LC50). Next, the embryos were exposed to distinct concentrations of the cocktail (LC50/2, LC50/5, LC50/10, and LC50/20) in a semi-static system. Samples were analyzed 0, 24, 48, and 96 h after exposure, and the drugs' concentrations in E3 medium were assessed by high-performance liquid chromatography. For embryotoxicity evaluation, the mortality, hatching, and heart rates; total length; and pericardial and yolk sac areas were determined. In addition, body malformations, edemas, presence of pigmentation, and histopathological assessments were also recorded. RESULTS: The LC50 values obtained for MTZ, ACM, and NMS were 4.69 mgmL-1, 799.98 µgmL-1, and 0.92 µgmL-1, respectively. No difference was observed between the drugs' nominal and observed concentrations at each time point. The cocktail significantly induced mortality and decreased hatching in the LC50/10, LC50/5, and LC50/2 groups. Additionally, body malformations, pigmentation loss, and yolk sac and pericardial edemas were observed in the cocktail groups. The cocktail groups' larvae had decreased total length and slower heart rates compared to the controls (p < 0.05). The histopathological assessment showed that yolk sac edema promoted severe histological changes in the esophageal-intestine junction and intestine in larvae treated with cocktails. Moreover, PAS-positive structures decreased in the esophageal-intestine junction, intestine, and liver in larvae exposed to pharmaceutical cocktails. CONCLUSION: This study's findings suggest the cocktail of ACM, MTZ, and NMS may be hazardous to aquatic organisms in case of environmental contamination.

Safety of metamizole (dipyrone) for the treatment of mild to moderate pain-an overview of systematic reviews.

Metamizole, as known as dipyrone or novaminsulfone is widely used, especially in Latin America, for its analgesic and antipyretic function. However, several countries have banned it due to the risk of agranulocytosis, skin necrosis, and other serious adverse effects. To assess the safety of metamizole compared to other commonly used non-opioid analgesics (paracetamol, ibuprofen, and acetylsalicylic acid). An overview of systematic reviews. The searches were performed in the PubMed, Cochrane Library, Embase, Scopus and LILACS databases. Systematic reviews of randomized and nonrandomized clinical trials with adult patients with mild to moderate pain that assessed the adverse effects of metamizole were included. A methodological quality assessment was performed through ROBIS. The protocol of this systematic review was submitted to the International Prospective Register of Systematic Reviews (Prospero, CRD42021295272). Of 387 identified studies, four were included, with a total of 20,643 participants, all submitted to a single dose by oral, intramuscular, or intravenous route. No study reported a serious adverse effect. However, 60 of 778 patients (7.7%) who used metamizole; 120/828 (14.5%) who used acetylsalicylic acid; 56/443 (12.6%) who used paracetamol; and 27/213 (12.7%) who used ibuprofen had mild adverse effects. A complementary statistical analysis showed that metamizole, at any dose, has a 38.8% lower chance of adverse effects compared to paracetamol and 46.8% compared to acetylsalicylic acid. The results shows that metamizole is a safe drug with evidence of a lower incidence of adverse effects compared to paracetamol and acetylsalicylic acid.

Risk of agranulocytosis with metamizole in comparison with alternative medications based on health records in Spain.

PURPOSE: We aimed to estimate the absolute (incidence) and relative (hazard ratio; HR) risk of agranulocytosis associated with metamizole in comparison with non-steroidal antiinflammatory drugs (NSAIDs). METHODS: A cohort study of new users of metamizole versus NSAIDs was performed with BIFAP (Pharmacoepidemiologic Research Database in Public Health Systems; Spain). Patients aged ≥ 2 years in 2005-2022 were followed up from the day after their first metamizole or NSAID dispensation till the end of the treatment period to identify patients hospitalized due to idiosyncratic agranulocytosis. Incidence rate (IR) and adjusted HR of agranulocytosis with metamizole versus NSAID were estimated assuming the onset date of agranulocytosis was the date of hospitalization sensitivity analysis or 7 days before (main analysis). In secondary analyses, we used (1) opioids-paracetamol as negative control and (2) any hospitalized neutropenia as outcome (assuming the onset was 7 days before). RESULTS: The cohorts included 444,972 new users of metamizole, 3,814,367 NSAID, and 3,129,221 opioids-paracetamol on continuous treatment during a median of 37-40 days. Overall, 26 hospitalized agranulocytosis occurred, 5 in the first week (and so removed in main analysis) and 21 thereafter. IR of agranulocytosis was 14.20 (N = 5 cases) and 8.52 (N = 3), 1.95 (N = 6) and 1.62 (N = 5), and 4.29 (N = 15) and 3.72 (N = 13)/107 person-weeks of continuous treatment using the date of hospitalization or 7 days before, respectively. Two, 0 and 2 of cases identified in both analyses had neoplasia in every cohort, respectively. HR of agranulocytosis associated with metamizole was 7.20 [95% CI: 1.92-26.99] and 4.40 [0.90-21.57] versus NSAID, and 3.31 [1.17-9.34] and 2.45 [0.68-8.83] versus opioid-paracetamol, respectively. HR of neutropenia with metamizole was 2.98 [1.57-5.65] versus NSAID. CONCLUSIONS: Agranulocytosis was very rare but more common (above 4 times more) with metamizole than other analgesics. The impact of the drug-induced agranulocytosis was less precise with metamizole than the comparators due to its lower use, which precluded to find statistical differences in main analysis. The increased risk of hospitalized neutropenias with metamizole supports the link with its severity although triggers unavailable during the follow-up (ex. cytotoxic medication) can not be discarded.

Prospective evaluation of the emetogenic profile and analgesic efficacy of intravenous ibuprofen and metamizole in the immediate postoperative period of pediatric acute appendicitis. / Evaluación prospectiva del perfil emético y la eficacia analgésica del ibuprofeno y el metamizol intravenosos en el postoperatorio inmediato de la apendicitis aguda pediátrica.

BACKGROUND: Literature comparing different alternatives for pain control in the immediate postoperative period of pediatric acute appendicitis (PAA) is scarce. MATERIALS AND METHODS: We prospectively compared the analgesic and emetogenic profile of intravenous ibuprofen and metamizole in the immediate postoperative period of PAA. For this purpose, we used a sample of patients operated on in 2021 in our center. Participants were recruited on arrival at the Emergency Department and histopathological confirmation of the diagnosis was obtained in all of them. Pain was evaluated every 8 hours after the surgery with validated visual analog scales ranging from 0 to 10 points. Repeated measures ANOVA was used to compare the evolution of pain in the 48 hours after surgery between the two groups. RESULTS: The sample included 95 patients (65% males) with a mean age of 9.7 years (sd: 3.14). 41 patients were treated with Ibuprofen (group 1) and 54 with metamizole (group 2). No significant differences were found in the level of pain either in the comparisons of point measurements or in its evolution in the 48 hours after surgery (p= 0.58). After adjusting for the received fluid therapy, children in the metamizole group had significantly more emetic episodes and needed significantly more doses of ondansetron. CONCLUSIONS: In our cohort, ibuprofen had a similar analgesic efficacy and a better emetogenic profile than metamizole in the immediate postoperative period of PAA. Future prospective, adequately controlled studies with larger sample sizes are needed to validate these findings.

INTRODUCCION: En la literatura existen pocas referencias que comparen las distintas alternativas disponibles para controlar el dolor en el postoperatorio inmediato de la apendicitis aguda pediátrica (AAP). MATERIAL Y METODOS: Comparación prospectiva del perfil analgésico y emético del ibuprofeno y el metamizol intravenosos en el postoperatorio inmediato de la AAP, para lo cual se recurre a una muestra de pacientes operados en 2021 en nuestro centro. Los participantes fueron reclutados a su llegada a Urgencias, obteniéndose confirmación histopatológica del diagnóstico en todos ellos. La evaluación del dolor se llevó a cabo cada 8 horas tras la cirugía mediante escalas analógicas visuales validadas, con valoraciones entre los 0 y los 10 puntos. Se realizó un ANOVA de las medidas repetidas entre los dos grupos para comparar la evolución del dolor en las 48 horas posteriores a la cirugía. RESULTADOS: La muestra estaba compuesta por un total de 95 pacientes (65% de ellos varones) con una edad media de 9,7 años (DT: 3,14). 41 pacientes fueron tratados con ibuprofeno (grupo 1) y 54 con metamizol (grupo 2). No se hallaron diferencias significativas en lo que respecta al dolor, ni en las comparaciones de las mediciones puntuales, ni en su evolución en las 48 horas posteriores a la cirugía (p= 0,58). Una vez realizado el ajuste correspondiente a la terapia de fluidos recibida, los niños del grupo metamizol tuvieron significativamente más episodios eméticos y necesitaron significativamente más dosis de ondansetrón. CONCLUSIONES: En nuestra cohorte, el ibuprofeno tuvo una eficacia analgésica similar y un mejor perfil emético que el metamizol en el postoperatorio inmediato de la AAP. Se hacen necesarios nuevos estudios prospectivos, adecuadamente controlados y con mayor tamaño muestral que validen estos hallazgos.

Case series: Heinz body formation in 13 multimorbid dogs following metamizole administration.

Background: Heinz Body (HB) anemia is a result of oxidative damage and is an uncommon condition in dogs relative to cats. In this retrospective case series, clinical features, laboratory values, concurrent diseases, and outcomes of 13 multimorbid dogs that developed HBs after receiving metamizole are reported. Case description: Of the 13 dogs in this case series that developed HBs, 10 were older and multimorbid, but the only feature that all the dogs had in common was receiving metamizole. HBs were detected in 7 out of 13 dogs within a few days (3-10 days) after starting metamizole treatment. The metamizole dose was 38-159 mg/kg/day. The highest percentage of HBs detected was 28-95% (mean, 46%). There was no correlation between the percentage of HBs and the daily dose of metamizole. All but 1 dog had mild-to-severe anemia at the time of the highest HB appearance. The number of HBs did not correlate with the hematocrit at that time. In 8/12 dogs, no stress leukogram was present. Approximately half of the dogs with HBs also had evidence of gastrointestinal hemorrhage, which could have masked additional oxidative damage. Conclusion: In multimorbid dogs that develop regenerative anemia after receiving metamizole, hemolysis due to HB development caused by oxidative damage should be considered as an important differential diagnosis.

Analysis of umbilical cord tissue as an indicator of in utero exposure to toxic adulterating substances.

In utero drug exposure is a significant public health threat to the well-being and normal development of the neonate. Recently, testing of umbilical cord tissue (UCT) has been employed to measure illicit drug exposure, as drugs used by the mother during the third trimester may be retained in the UCT. Focus has also been given to potential adverse health effects among drug users, resulting from exposure to pharmacologically active adulterants and cutting agents in the street drug supply. The in utero effects of these substances have not been well studied in humans, nor has their presence been demonstrated as a means for assessing adverse health effects in the neonate. Here, we describe the application of a novel test method to analyze UCT for the presence of more than 20 common adulterating/cutting substances via LC/Q-TOF. In total, 300 de-identified UCT samples were analyzed-all had previously tested positive for cocaine or opiates. Generally, the positivity rates of individual compounds were similar between the Cocaine and Opiates Subgroups, apart from levamisole, xylazine, dipyrone (metabolites), and promethazine. Many of the adulterants used in the street drug supply do have legitimate medicinal/therapeutic uses, including several of the compounds most frequently detected in this study. Caffeine and lidocaine were the most frequently identified compounds both individually (>70% each) and in combination with each other. Alternatively, levamisole, an adulterant with no legitimate therapeutic use, was present in 12% of cases. Importantly, this data demonstrates that the detection of traditional drugs of abuse may serve as indicators of potential in utero exposure to toxic adulterating substances during gestation. While there is cause for concern with respect to any unintentional drug exposure, illicit drug use during pregnancy, including uncontrolled dosing, poly-adulterant consumption, and the interactions of these drug mixtures, produces a significant public health threat to the neonate which warrants further study.

A Case Report on Metamizole-Induced Agranulocytosis: Is the Benefit Worth the Risk?

Metamizole is a drug with analgesic and antipyretic properties widely available in Portugal. Its use is highly controversial because of the risk of agranulocytosis, a rare but serious adverse event. A 70-year-old female patient with a recent history of treatment with metamizole for post-surgery fever and pain presented to the ED with sustained fever, diarrhea, and painful mouth ulcers. Laboratory tests revealed agranulocytosis. The patient was placed under protective isolation and started treatment with granulocyte-colony stimulating factor (G-CSF) and empiric antibiotic therapy with piperacillin/tazobactam and vancomycin for neutropenic fever. After an extensive workup, no source of infection was identified. During hospitalization, infectious and neoplastic causes of agranulocytosis were investigated, but the results were negative. Metamizole-induced agranulocytosis was suspected. The patient completed a total of three days of G-CSF and eight days of empiric antibiotic therapy with sustained clinical improvement. She was discharged completely asymptomatic and remained clinically stable during follow-up without a resurgence of agranulocytosis. This case report is intended to increase awareness of metamizole-induced agranulocytosis. While this is a well-known side effect, it is also often overlooked. It is paramount that both physicians and patients know how to correctly manage metamizole to prevent and promptly treat agranulocytosis.

Assessment of local pain and analgesia in envenoming by wandering spiders (Phoneutria spp.).

Phoneutrism (bites by wandering spiders of the genus Phoneutria) frequently results in local pain. We describe a retrospective cohort study of a case series of phoneutrism admitted to our Emergency Department (ED), in which we used the Numeric Pain Rating Scale (NPRS 0-10) to assess the intensity of local pain upon admission, and recorded the analgesic measures used to control this pain. Other criteria for inclusion were: (1) An age ≥8 years, (2) Treatment exclusively at our ED, and (3) Visualization or photographing the spider at the time of the bite and/or bringing the spider for identification. The patients were classified into three groups based on the intensity of pain at admission: group 1 - mild or no pain (NPRS: 0-3), group 2 - moderate pain (NPRS: 4-6), and group 3 - intense or severe pain (NPRS: 7-10). Fifty-two patients fulfilled the inclusion criteria (n = 11, 14 and 27 in groups 1, 2, and 3, respectively), with a median age of 37 years. The median NPRS upon admission was 7 (interquartile range: 5-8). In patients with an NPRS <7 (groups 1 and 2), only dipyrone was used to alleviate the pain, with six cases in group 1 requiring no analgesia. Most of the cases in group 3 (19/27) were treated with a local anesthetic infiltration (2% lidocaine), in association with analgesics given i.v. in 16 cases (dipyrone, 14; tramadol, 2); additional analgesic treatment was required in seven cases, six of which were treated with tramadol i.v. The median time spent in the ED was 18, 58 and 120 min for groups 1, 2 and 3, respectively. These findings show that most cases of envenoming by Phoneturia spp. involved intense local pain (NPRS ≥7), with local anesthetics being used only in these cases, often in association with dipyrone i.v.

Time course of CYP3A activity during and after metamizole (dipyrone) in healthy volunteers.

AIMS: In patients of all ages, metamizole is a frequently used analgesic. Recently, metamizole has been identified as an inducer of, among others, cytochrome P450 (CYP) 3A activity, but the time course of this interaction has not been evaluated. METHODS: Using repeated oral microdoses (30 µg) of the CYP3A index substrate midazolam, we assessed changes in midazolam pharmacokinetics (area under the concentration-time curve from 2-4 h: AUC2-4 and estimated partial metabolic clearance: eClmet ) before, at steady-state, and after discontinuation of 3 × 1000 mg metamizole/day orally for 8 days. RESULTS: Significant changes in pharmacokinetic parameters were detected already 3 days after start of metamizole treatment. At the steady-state of enzyme induction, the geometric mean ratio of midazolam AUC2-4 was substantially reduced to 0.18 (90% confidence interval: 0.14-0.24) with a corresponding 5.43-fold (4.15-7.10) increase of eClmet . After discontinuation of metamizole, the changes slowly recovered, but were still significant at the end of the observation period on the fifth day after discontinuation of metamizole therapy (AUC2-4 reduced to 0.50 [0.41-0.63] and eClmet 1.99-fold increased [1.60-2.47, P < 0.05]). CONCLUSION: Metamizole acts as a strong inducer of CYP3A already few days after start of metamizole administration and, thus, should be avoided in patients using drugs with narrow therapeutic index and major clearance via CYP3A. If their administration is essential, close monitoring and dose adjustment of comedication should be performed as early as the first week after the initiation and after discontinuation of metamizole therapy.

Real-world evidence for beneficial effects of dipyrone in 4,278 patients with pulmonary hypertension - Analysis of the risk of ventilation, hospitalization, and agranulocytosis.

INTRODUCTION: Dipyrone has been used as an analgesic for a century, but recently was proposed as a novel therapeutic strategy for the prevention and therapy of pulmonary hypertension (PH). The aim of this study was to analyze whether the risk for ventilation procedures and hospitalization was lower among patients with PH who used dipyrone compared to subjects who did not use dipyrone. MATERIALS AND METHODS: Initially, patients with PH were retrieved from the TriNetX database, whereby subjects who used dipyrone were assigned to cohort I, and cohort II was formed by those individuals who did not use dipyrone. Both cohorts were matched for several variables. The outcomes were requirement for ventilation procedures and hospital admission, whereby the time window to record events was 5 years after diagnosis of PH. Subsequently, risk analysis was carried out, and risk ratio (RR) and odds ratio (OR) were calculated. In addition, the risk of agranulocytosis was determined for both cohorts. RESULTS: Out of 741,875 individuals diagnosed with PH 4,282 and 737,593 patients were assigned to the cohorts I and II. After matching, each cohort accounted for 4,278 individuals. Among the cohorts I and II 10 and 187 individuals required ventilation procedures. The according risks of 0.2% vs. 4.4% were significantly different (p < 0.0001; Log-Rank test). RR and OR were 0.053 and 0.051. Within the cohorts I and II 10 and 1,195 subjects required hospital admission. The risks of hospitalization of 0,4% vs. 27.9% differed significantly (p < 0.0001). RR and OR were 0.016 and 0.012. Among the cohorts I and II 47 and 66 individuals were diagnosed with agranulocytosis, whereby no significance was found (p > 0.05). CONCLUSIONS: The risk for ventilation measures and hospitalization among patients with PH was found to be significantly lower when dipyrone was used. Even though the underlying mechanisms remain unknown to date, they are supposedly mediated by an active metabolite of dipyrone. The obtained results appear to be promising for patients suffering from PH. Hence, the present study may encourage further research.

Pharmacokinetic profiles of the two major active metabolites of metamizole, 4-methylaminoantipyrine (MAA) and 4-aminoantipyrine (AA), after intravenous injection in cats.

This study aimed to determine the pharmacokinetic profile of two active metabolites of metamizole (dipyrone), N-methyl-4-aminoanthypyrine (MAA) and 4-aminoanthypyrine (AA), after intravenous administration in cats. Eight healthy mixed-breed cats were intravenously administered metamizole (25 mg/kg). Blood samples were collected at predetermined time points for up to 48 h after administration. Information on behavioral changes in the animals and adverse effects was collected. Plasma aliquots were processed and analyzed using the ultra-performance liquid chromatography tandem mass spectrometry technique. A validated UPLC-MS/MS method was used to characterize the pharmacokinetics of MAA and AA. Salivation was identified as an adverse clinical sign. The mean maximal plasma concentrations of MAA and AA were 29.31 ± 24.57 µg/mL and 1.69 ± 0.36 µg/mL, with half-lives of around 4.98 and 14 h, respectively. The area under the plasma concentration curve values were 28.54 ± 11.33 and 49.54 ± 11.38 h*µg/mL for MAA and AA, respectively. The plasma concentration of MAA was detectable for up to 24 h and was smaller than AA. AA was detectable for >48 h. Results suggest that metamizole is converted into active metabolites in cats. Further PK/PD and safety studies should be performed before defining the dose or administration intervals for clinical use.

Unmasking of Metamizole-induced Liver Injury by Simult aneous Development of Characteristic Agranulocytosis.

BACKGROUND: Metamizole is one of the most used analgesic, antipyretic, and spasmolytic agents in many countries worldwide. While metamizole-induced agranulocytosis is an, albeit seldom, well-known adverse event, metamizole-associated drug-induced liver injury has been reported rarely in the literature and hence often remains unconsidered. Here, we present a unique case where metamizole-induced hepatotoxicity got unmasked by the simultaneous development of characteristic agranulocytosis. CASE REPORT: A 22-year-old woman without known conditions presented with a new onset of fever, jaundice, and maculopapular rash and explicitly denied intake of any new substances. Laboratory tests showed liver injury, granulopenia, and positive anti-nuclear and anti-mitochondrial (AMA-M2) antibodies. Liver biopsy revealed a histological pattern characteristic of drug-induced liver injury and bone marrow biopsy, the classical picture of metamizole-induced agranulocytosis. Indeed the in-depth interview of the patient unveiled metamizole consumption over the last two months. Therefore, we could diagnose metamizole-induced hepato- and myelotoxicity. Accordingly, steroid therapy led to normalization of liver parameters and stimulation with granulocyte colony- stimulating factor to leukocyte recovery. CONCLUSION: This case report is intended to increase the awareness of metamizole-associated druginduced liver injury which should always be kept in mind due to its occasionally life-threatening course. Diagnosis can be difficult particularly if anamnesis and written records are without hints for prior metamizole intake.

Perfil prescriptivo de corticoides en el servicio de urgencias del Hospital Odontológico de la ciudad de Formosa, Argentina / Prescriptive Profile of Corticoids in the Emergency Department of the Dental Hospital of the City of Formosa, Argentina

Objetivo: identificar el perfil prescriptivo de corticoides en pacientes que asistieron al Servicio de Urgencias del Hospital Odontológico de la ciudad de Formosa, Argentina. Métodos: se realizó un estudio transversal, observacional y descriptivo, se analizaron las prescripciones de corticoides realizadas por odontólogos que atendieron en el Servicio de Urgencias del Hospital Odontológico de la ciudad de Formosa desde marzo 2019 a febrero 2020. Las variables de estudio fueron: características demográficas del paciente, diagnóstico clínico odontológico, corticoide prescrito, dosis y forma farmacéutica. Resultados: de un total de 9.635 historias clínicas, se observaron 3.244 prescripciones de corticoides (33,6%). De acuerdo a los corticoides prescritos, se halló a la dexametasona para vía intramuscular y además se utilizó dexametasona en tratamientos combinados con dipirona para vía intramuscular e ibuprofeno para vía oral. Los diagnósticos relacionados con prescripción de estos medicamentos fueron: pulpitis, periodontitis apical aguda, flemón/absceso, entre otras. De acuerdo al valor intrínseco terapéutico potencial, los fármacos prescritos en el hospital odontológico son de valor elevado, esto significa que demostraron eficacia para el tratamiento, el diagnóstico o la prevención de enfermedades del ser humano. Conclusiones: el estudio de la utilización de medicamentos en el Hospital Odontológico de la ciudad de Formosa permitió observar situaciones donde los corticoides no están indicados. Además, se señala la prescripción excesiva de la vía intramuscular. A partir de los resultados obtenidos es necesario realizar una retroalimentación a los prescriptores, por lo que se sugieren intervenciones para elaborar propuestas de solución a los problemas identificados y formular políticas de medicamentos.

Objective: to identify the prescriptive profile of corticosteroids in patients who were treated at the Emergency Service of the Dental Hospital of the City of Formosa, Argentina. Methods: a cross-sectional, observational, and descriptive study was carried out, and corticosteroid prescriptions made by dentists who attended the Emergency Service of the Dental Hospital of the City of Formosa, from March 2019 to February 2020 were analyzed. The study variables were: demographic characteristics of the patient, dental clinical diagnosis, corticosteroid prescribed, dose, and pharmaceutical form. Results: Of 9,635 medical records, 3,244 corticosteroid prescriptions (33.6%) were observed. According to the prescribed corticosteroids, dexamethasone was found for the intramuscular route, and dexamethasone was also used in combined treatments with dipyrone for the intramuscular route and ibuprofen for the oral route. The diagnoses related to the prescription of these medications were: pulpitis, acute apical periodontitis, phlegmon/abscess, trauma, pericoronitis, hypersensitivity and alveolitis. According to the potential therapeutic intrinsic value, the drugs prescribed in the dental hospital are of high value, which means that they have demonstrated efficacy for the treatment, diagnosis or prevention of diseases that affect humans. Conclusions: the study of the use of drugs in the Dental Hospital of the City of Formosa allowed us to observe situations where corticosteroids are not indicated. In addition, the excessive prescription of the intramuscular route is pointed out. Based on the results obtained, it is necessary to provide feedback to the prescribers, so it is suggested to continue with different interventions to develop proposals for solutions to the identified problems and formulate drug policies.

2-Arylpropionic Acid Pyrazolamides as Cannabinoid CB2 Receptor Inverse Agonists Endowed with Anti-Inflammatory Properties.

Among the most recent proposals regarding the mechanism of action of dipyrone, the modulation of cannabinoid receptors CB1 and CB2 appears to be a promising hypothesis. In this context, the present work describes a series of five novel pyrazolamides (7-11) designed as molecular hybrids of dipyrone metabolites and NSAIDs, such as ibuprofen and flurbiprofen. Target compounds were obtained in good overall yields (50-80%) by classical amide coupling between 4-aminoantipyrine and arylacetic or arylpropionic acids, followed in some cases by N-methylation of the amide group. The compounds presented good physicochemical properties in addition to stability to chemical (pH 2 and 7.4) and enzymatic (plasma esterases) hydrolysis and showed medium to high gastrointestinal and BBB permeabilities in the PAMPA assay. When subjected to functional testing on CB1- or CB2-transfected cells, compounds demonstrated an inverse agonist profile on CB2 receptors and the further characterization of compound LASSBio-2265 (11) revealed moderate binding affinity to CB2 receptor (Ki = 16 µM) with an EC50 = 0.36 µM (Emax = 63%). LASSBio-2265 (11) (at 1, 3, and 10 mg/kg p.o.) was investigated in the formalin test in mice and a remarkable analgesic activity in the late inflammatory phase was observed, suggesting it could be promising for the treatment of pain syndromes associated with chronic inflammatory diseases.

Design, synthesis and in vivo evaluation of 1,4-dioxo-2-butenyl aryl amine derivatives as a promising anti-inflammatory drug prototype.

Inflammation is a natural response of the organism to an infection, trauma, or cellular stress. Pain is the first symptom of acute and chronic inflammation. The standard class of medication to treat inflammatory pain is the nonsteroidal anti-inflammatory drug (NSAID). These drugs are associated with severe side effects such as gastric ulcers, gastritis, or internal bleeding. One of NSAIDs, Dipyrone® (metamizole) is largely used in many European and South American countries despite its dubious effectivity and its withdrawal from the market of several countries. Here, aiming to identify a new anti-inflammatory drug prototype based on Dipyrone® structure, a set of 27 molecules were virtually screened, and 4 compounds containing the active metabolite 4-aminoantipyrine and 1,4-dioxo-2-butenyl fragment were selected for docking, synthesis, and biological evaluation. The selection was based on the number of H-bonds and π- π stacking interactions between the inhibitor and the amino acids within the binding site of the enzyme. Carrageenan-induced paw edema, acetic acid-induced writhing, and formalin assays were used to evaluate inflammation and pain response. The selected compounds 1-4 inhibited the involvement of biogenic amines in the formation of paw edema. Compounds 1-4 also reduced pain in the inflammatory response phase. It has to be noted that 4-AA may cause agranulocytosis, which should be borne in mind when developing drug candidates of similar structure. Our new drug prototypes based on 4-aminoantipyrine and 1,4-dioxo-2-butenyl moieties open a gate for developing a prototype of nonsteroidal anti-inflammatory drugs.