RESUMEN
BACKGROUND: The Global COVID Vaccine Safety (GCoVS) Project, established in 2021 under the multinational Global Vaccine Data Network™ (GVDN®), facilitates comprehensive assessment of vaccine safety. This study aimed to evaluate the risk of adverse events of special interest (AESI) following COVID-19 vaccination from 10 sites across eight countries. METHODS: Using a common protocol, this observational cohort study compared observed with expected rates of 13 selected AESI across neurological, haematological, and cardiac outcomes. Expected rates were obtained by participating sites using pre-COVID-19 vaccination healthcare data stratified by age and sex. Observed rates were reported from the same healthcare datasets since COVID-19 vaccination program rollout. AESI occurring up to 42 days following vaccination with mRNA (BNT162b2 and mRNA-1273) and adenovirus-vector (ChAdOx1) vaccines were included in the primary analysis. Risks were assessed using observed versus expected (OE) ratios with 95 % confidence intervals. Prioritised potential safety signals were those with lower bound of the 95 % confidence interval (LBCI) greater than 1.5. RESULTS: Participants included 99,068,901 vaccinated individuals. In total, 183,559,462 doses of BNT162b2, 36,178,442 doses of mRNA-1273, and 23,093,399 doses of ChAdOx1 were administered across participating sites in the study period. Risk periods following homologous vaccination schedules contributed 23,168,335 person-years of follow-up. OE ratios with LBCI > 1.5 were observed for Guillain-Barré syndrome (2.49, 95 % CI: 2.15, 2.87) and cerebral venous sinus thrombosis (3.23, 95 % CI: 2.51, 4.09) following the first dose of ChAdOx1 vaccine. Acute disseminated encephalomyelitis showed an OE ratio of 3.78 (95 % CI: 1.52, 7.78) following the first dose of mRNA-1273 vaccine. The OE ratios for myocarditis and pericarditis following BNT162b2, mRNA-1273, and ChAdOx1 were significantly increased with LBCIs > 1.5. CONCLUSION: This multi-country analysis confirmed pre-established safety signals for myocarditis, pericarditis, Guillain-Barré syndrome, and cerebral venous sinus thrombosis. Other potential safety signals that require further investigation were identified.
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COVID-19 , Síndrome de Guillain-Barré , Miocarditis , Pericarditis , Trombosis de los Senos Intracraneales , Humanos , Vacuna nCoV-2019 mRNA-1273 , Vacuna BNT162 , Estudios de Cohortes , COVID-19/prevención & control , Vacunas contra la COVID-19/efectos adversos , Síndrome de Guillain-Barré/inducido químicamente , Síndrome de Guillain-Barré/epidemiología , Vacunas de ARNm , Vacunación/efectos adversos , Masculino , FemeninoRESUMEN
Coadministration of dihydroartemisinin-piperaquine (DHA-PQ) with fat may improve bioavailability and antimalarial efficacy, but it might also increase toxicity. There have been no studies of these potential effects in the pediatric age group. The tolerability, safety, efficacy, and pharmacokinetics of DHA-PQ administered with or without 8.5 g fat were investigated in 30 Papua New Guinean children aged 5 to 10 years diagnosed with uncomplicated falciparum malaria. Three daily 2.5:11.5-mg-base/kg doses were given with water (n = 14, group A) or milk (n = 16, group B), with regular clinical/laboratory assessment and blood sampling over 42 days. Plasma PQ was assayed by high-performance liquid chromatography with UV detection, and DHA was assayed using liquid chromatography-mass spectrometry. Compartmental pharmacokinetic models for PQ and DHA were developed using a population-based approach. DHA-PQ was generally well tolerated, and initial fever and parasite clearance were prompt. There were no differences in the areas under the concentration-time curve (AUC0-∞) for PQ (median, 41,906 versus 36,752 µg · h/liter in groups A and B, respectively; P = 0.24) or DHA (4,047 versus 4,190 µg · h/liter; P = 0.67). There were also no significant between-group differences in prolongation of the corrected electrocardiographic QT interval (QTc) initially during follow-up, but the QTc tended to be higher in group B children at 24 h (mean ± standard deviation [SD], 15 ± 10 versus 6 ± 15 ms(0.5) in group A, P = 0.067) and 168 h (10 ± 18 versus 1 ± 23 ms(0.5), P = 0.24) when plasma PQ concentrations were relatively low. A small amount of fat does not change the bioavailability of DHA-PQ in children, but a delayed persistent effect on ventricular repolarization cannot be excluded.
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Antimaláricos/efectos adversos , Antimaláricos/farmacocinética , Artemisininas/efectos adversos , Artemisininas/farmacocinética , Malaria/sangre , Quinolinas/efectos adversos , Quinolinas/farmacocinética , Antimaláricos/administración & dosificación , Antimaláricos/uso terapéutico , Artemisininas/administración & dosificación , Niño , Femenino , Hemodinámica/efectos de los fármacos , Humanos , Malaria/tratamiento farmacológico , Masculino , Quinolinas/administración & dosificaciónRESUMEN
An alternative antimalarial pathway of an 'outdated' drug, chloroquine (CQ), may facilitate its return to the shrinking list of effective antimalarials. Conventionally, CQ is believed to interfere with hemozoin formation at nanomolar concentrations, but resistant parasites are able to efflux this drug from the digestive vacuole (DV). However, we show that the DV membrane of both resistant and sensitive laboratory and field parasites is compromised after exposure to micromolar concentrations of CQ, leading to an extrusion of DV proteases. Furthermore, only a short period of exposure is required to compromise the viability of late-stage parasites. To study the feasibility of this strategy, mice malaria models were used to demonstrate that high doses of CQ also triggered DV permeabilization in vivo and reduced reinvasion efficiency. We suggest that a time-release oral formulation of CQ may sustain elevated blood CQ levels sufficiently to clear even CQ-resistant parasites.
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Antimaláricos , Cloroquina , Malaria/tratamiento farmacológico , Plasmodium/metabolismo , Animales , Antimaláricos/farmacocinética , Antimaláricos/farmacología , Cloroquina/farmacocinética , Cloroquina/farmacología , Modelos Animales de Enfermedad , Evaluación de Medicamentos , Hemoproteínas/metabolismo , Malaria/sangre , Ratones , Ratones Endogámicos BALB CRESUMEN
Reduced plasma retinol concentrations occur in human malaria but the benefits of supplementation remain uncertain. We assessed the in vivo efficacy of retinol administration, and its effect on lipid peroxidation, in a Plasmodium berghei murine model. Animals received vehicle (n=17) or retinol (i) before P. berghei inoculation (four doses), (ii) at parasitaemia 10-15% (three to four doses) or (iii) before and after inoculation (six to seven doses; n=15 in each group), with euthanasia on day 8 post-inoculation or when the parasitaemia exceeded 50%. Multiple-dose pre-inoculation retinol reduced endpoint parasitaemia by 24% (P=0.001 versus controls). A reduction of 18% (P=0.042) was observed when retinol was given to parasitaemic animals. Retinol was ineffective when given both before and after infection (11% reduction; P=0.47). Although retinol supplementation did not change plasma retinol concentrations, liver retinol content increased and correlated inversely with endpoint parasitaemia (r=-0.45, P=0.001). Malaria infection augmented concentrations of the free radical lipid peroxidation end-product F(2)-isoprostanes in plasma, erythrocytes and liver by 1.8-, 2.8- and 4.9-fold, respectively, but retinol supplementation had no effect on these increases. Consistent with some human malaria studies, prophylactic retinol reduces P. berghei parasitaemia. This effect relates to augmentation of tissue retinol stores rather than to retinol-associated changes in oxidant status.
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Antimaláricos/administración & dosificación , Peroxidación de Lípido/fisiología , Malaria/tratamiento farmacológico , Plasmodium berghei/aislamiento & purificación , Vitamina A/administración & dosificación , Administración Oral , Animales , Ácido Araquidónico/análisis , Modelos Animales de Enfermedad , Relación Dosis-Respuesta a Droga , Esquema de Medicación , F2-Isoprostanos/análisis , Ácidos Grasos Insaturados/análisis , Inyecciones Intraperitoneales , Hígado/metabolismo , Malaria/sangre , Malaria/metabolismo , Masculino , Ratones , Ratones Endogámicos BALB C , Parasitemia/dietoterapia , Parasitemia/metabolismo , Proyectos Piloto , Vitamina A/análisis , Vitamina A/sangreRESUMEN
The study was a comparison of bioassay and HPLC analysis of artesunate (ARTS) and dihydroartemisinin (DHA) in plasma. ARTS and DHA in plasma samples from patients treated with ARTS were quantified by HPLC and expressed as DHA. DHA-equivalents in the same plasma samples were measured using a standardised parasite culture technique. DHA concentrations estimated by both methods were highly correlated (bioassay=0.96 x HPLC+11.0; r2=0.92). At high concentrations (>12000 nmol/l) bioassay sometimes overestimated DHA. Bioassay of active drug in plasma correlates well with specific chemical analysis by HPLC. ARTS and DHA appear to account for the total antimalarial activity in plasma after ARTS administration.
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Antimaláricos/sangre , Artemisininas/sangre , Malaria Falciparum/sangre , Plasmodium falciparum , Sesquiterpenos/sangre , Animales , Antimaláricos/uso terapéutico , Artemisininas/uso terapéutico , Artesunato , Bioensayo , Cromatografía Líquida de Alta Presión , Humanos , Concentración 50 Inhibidora , Malaria Falciparum/tratamiento farmacológico , Sesquiterpenos/uso terapéuticoRESUMEN
Abdominal defensive glands of both sexes of the Gulf fritillary butterfly, Agraulis vanillae (Linnaeus) (Nymphalidae:Heliconiinae) emit a pronounced odor when disturbed. We have identified 6-methyl-5-hepten-2-one; oleic, palmitic, and stearic esters of the corresponding alcohol 6-methyl-5-hepten-2-ol; hexadecyl acetate; 1,16-hexadecanediol diacetate; and 1,15-hexade-canediol diacetate in the glandular exudate. Since we have determined that free-flying birds or birds in a butterfly conservatory discriminate against A. vanillae as prey, we suggest that the constituents in the glands may play a defensive role against potential avian predators.
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Acetatos/aislamiento & purificación , Glándulas Exocrinas/química , Lepidópteros/fisiología , Abdomen , Acetatos/química , Animales , Aves , Femenino , Masculino , Odorantes , Conducta PredatoriaRESUMEN
AIMS: To obtain comprehensive bioavailability data for artesunate (ARTS) and its active metabolite dihydroartemisinin (DHA) following their separate oral administration to Vietnamese volunteers and to patients with acute, uncomplicated falciparum malaria. METHODS: Volunteers were randomized to receive either i.v. ARTS (120 mg) followed by oral ARTS (150 mg) 8 h later (Group 1, n = 10), or i.v. ARTS (120 mg) followed by oral DHA (120 mg) 8 h later. Patients, also received oral ARTS (150 mg; Group 3, n = 8) or DHA (120 mg; Group 2, n = 7), in a randomized cross-over study design. Multiple blood samples were collected after each administration and plasma ARTS and/or DHA concentrations were determined by h.p.l.c. Pharmacokinetic descriptors were obtained from noncompartmental analysis and bioavailability was calculated from AUC data. In the patients, the time to 50% parasite clearance (PCT50) and fever clearance time (FCT) also were measured. RESULTS: In Group 1 (volunteers), the mean (95% CI) absolute bioavailability of oral ARTS was 80% (62,98%), while in Group 2 (volunteers), the bioavailability of oral DHA was 45% (34,56%). In the patients (Group 3), the bioavailability of oral DHA relative to oral ARTS was 88% (49,127%). The median PCT50 and FCT were 2.3 and 28 h, respectively. CONCLUSIONS: The study shows that the absolute bioavailability of DHA was significantly lower than that for ARTS in healthy volunteers. The bioavailability of ARTS in volunteers was consistent with previous studies in patients with uncomplicated falciparum malaria. The dose-normalized Cmax and AUC(0,infinity) for DHA were significantly greater in patients with falciparum malaria than in healthy volunteers. The high relative bioavailability of DHA in the patients may have been due to lower first-pass clearance. We conclude that, for the treatment of malaria, DHA is likely to be a suitable oral substitute for ARTS. Based on our mean AUC measurements, it appears that equal doses of DHA and ARTS (mg basis) should give equivalent systemic exposure to bioactive DHA in uncomplicated falciparum malaria.
Asunto(s)
Antimaláricos/metabolismo , Artemisininas , Disponibilidad Biológica , Malaria Falciparum/metabolismo , Sesquiterpenos/farmacocinética , Administración Oral , Adulto , Antimaláricos/uso terapéutico , Estudios Cruzados , Relación Dosis-Respuesta a Droga , Semivida , Humanos , Inyecciones Intravenosas , Malaria Falciparum/tratamiento farmacológico , Malaria Falciparum/parasitología , Tasa de Depuración Metabólica/fisiología , Sesquiterpenos/administración & dosificación , Sesquiterpenos/sangre , Factores de Tiempo , VietnamRESUMEN
To provide novel data relating to the dispositions, effects, and toxicities of the artemisinin derivatives in severe malaria, we studied 30 Vietnamese adults with slide-positive falciparum malaria treated with intravenous artesunate. Twelve patients with complications (severe; group 1) and 8 patients without complications but requiring parenteral therapy (moderately severe; group 2) received 120 mg of artesunate by injection, and 10 patients with moderately severe complications (group 3) were given 240 mg by infusion. Serial concentrations of artesunate and its active metabolite dihydroartemisinin in plasma were measured by high-performance liquid chromatography. The time to 50% parasite clearance (PCT(50)) was determined from serial parasite densities. Full clinical (including neurological) assessments were performed at least daily. In noncompartmental pharmacokinetic analyses, group mean artesunate half-lives (t(1/2)) were short (range, 2.3 to 4.3 min). The dihydroartemisinin t(1/2) (range, 40 to 64 min), clearance (range, 0.73 to 1.01 liters/h/kg), and volume of distribution (range, 0.77 to 1.01 liters/kg) were also similar both across the three patient groups (P > 0.1) and to previously reported values for patients with uncomplicated malaria. Parasite clearance was prompt (group median PCT(50) range 6 to 9 h) and clinical recovery was complete under all three regimens. These data indicate that the pharmacokinetics of artesunate and dihydroartemisinin are not influenced by the severity of malaria. Since the pharmacokinetic parameters for both artesunate and dihydroartemisinin were similar regardless of whether injection or infusion was used, artesunate can be considered a prodrug that is converted stoichiometrically to dhydroartemisinin. Conventional doses of artesunate are safe and effective when given to patients with complications of falciparum malaria.
Asunto(s)
Antimaláricos/farmacocinética , Antimaláricos/uso terapéutico , Artemisininas , Malaria Falciparum/tratamiento farmacológico , Malaria Falciparum/metabolismo , Sesquiterpenos/farmacocinética , Sesquiterpenos/uso terapéutico , Adulto , Área Bajo la Curva , Artesunato , Femenino , Semivida , Humanos , Infusiones Intravenosas , Malaria Falciparum/psicología , MasculinoRESUMEN
To investigate the pharmacokinetic and pharmacodynamic properties of artesunate (ARTS) and its active metabolite dihydroartemisinin (DHA) in Plasmodium vivax infections, 12 male Vietnamese adults with slide-positive vivax malaria received either intravenous ARTS (120 mg; group 1) or oral ARTS (100 mg; group 2) with the alternative preparation given 8 hr later in a randomized, open, cross-over study. Following intravenous injection, ARTS had a peak plasma drug concentration (Cmax) of 35.6 microM (13.7 mg/L), an elimination half-life (t1/2) of 2.2 min, a clearance (CL) of 3.0 L/hr/kg, and a volume of distribution (V) of 0.16 L/kg. Dihydroartemisinin had a Cmax of 7.7 microM (2.2 mg/L), a tmax of 8 min, a t1/2 of 37 min, an apparent CL of 1.1 L/hr/kg, and an apparent V of 0.9 L/kg. Following oral ARTS, the mean relative bioavailability of DHA was 85%, the Cmax was 3.0 microM (0.85 mg/L), the tmax was 75 min, and t1/2 was 40 min. The mean time to 50% reduction in the parasite count (PCT50) and median fever clearance time were 3 hr and 16 hr, respectively. Following intravenous ARTS (group 1), the PCT50 for total parasites, rings, trophozoites, and gametocytes was 3.3 hr, 3.2 hr, 4.0 hr, and 3.6 hr, respectively. This study confirms that ARTS is effective against P. vivax, with rapid clearance of sexual and asexual forms of the parasite. Artesunate is a suitable initial treatment for vivax malaria, or when the plasmodial species cannot be reliably identified.
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Antimaláricos/farmacología , Antimaláricos/farmacocinética , Artemisininas , Malaria Vivax/tratamiento farmacológico , Malaria Vivax/metabolismo , Sesquiterpenos/farmacología , Sesquiterpenos/farmacocinética , Administración Oral , Adulto , Animales , Antimaláricos/administración & dosificación , Artesunato , Disponibilidad Biológica , Estudios Cruzados , Semivida , Humanos , Inyecciones Intravenosas , Malaria Vivax/parasitología , Masculino , Parasitemia/tratamiento farmacológico , Parasitemia/metabolismo , Parasitemia/parasitología , Plasmodium vivax/efectos de los fármacos , Plasmodium vivax/crecimiento & desarrollo , Plasmodium vivax/aislamiento & purificación , Sesquiterpenos/administración & dosificación , VietnamRESUMEN
1. The clearance of dihydroartemisinin (DHA) in control and malaria-infected (MI) rats was investigated using the isolated perfused rat liver (IPRL) model and hepatic microsomal studies. 2. In the recirculating IPRL, clearance of DHA was reduced from a mean (s.d.) of 8.2+/-1.8 ml min(-1) in controls (n=8) to 6.0+/-1.0 ml min(-1) in MI (n=8; P<0.01). Clearance in control livers was similar to the perfusion flow rate, suggesting a high hepatic extraction ratio for DHA. 3. Single-pass IPRL studies in controls (n=8) showed that DHA bioavailability at 1.3, 8 and 38 microm was 0.026+/-0.020, 0.043+/-0.025 and 0.14+/-0.06, respectively (P<0.001 for 8 microM vs 38 microM). In MI livers (n=5), DHA bioavailability at 8 and 38 microM was 0.18+/-0.07 and 0.40+/-0.08, respectively (P=0.002). Bioavailability was higher in the MI group than in controls (P=0.01 at 8 microM and P<0.001 at 38 microM). DHA-glucuronide was the sole biliary metabolite. 4. Hepatic microsomal studies of DHA-glucuronide formation showed a significantly lower Vmax but no significant change in Km, in MI compared to control livers (n=6). Intrinsic metabolic clearance (Vmax/Km) was higher in control than in MI livers (5.2+/-1.3 and 2.5+/-1.4 microl min(-1) mg(-1), respectively; P=0.006). 5. These studies demonstrate that DHA has a high, concentration-dependent hepatic extraction ratio that is reduced by 20-30% in the P. berghei rodent malaria model. The impaired hepatic clearance of DHA in MI is attributable to a reduction in intrinsic metabolic clearance.
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Antimaláricos/farmacocinética , Artemisininas , Malaria/metabolismo , Microsomas Hepáticos/metabolismo , Sesquiterpenos/farmacocinética , Animales , Sistema Biliar/metabolismo , Glucuronatos/metabolismo , Masculino , Tasa de Depuración Metabólica , Perfusión , Ratas , Ratas Wistar , Sesquiterpenos/metabolismoRESUMEN
AIMS: To obtain comprehensive pharmacokinetic and pharmacodynamic data for artesunate (ARTS) and its active metabolite dihydroartemisinin (DHA) following i.v. and oral administration of ARTS to patients with acute, uncomplicated falciparum malaria. METHODS: Twenty-six Vietnamese patients with falciparum malaria were randomized to receive either i.v. ARTS (120 mg; group 1) or oral ARTS (100 mg; group 2), with the alternative preparation given 8 h later in an open crossover design. Mefloquine (750 mg) was administered at 24 h. Plasma concentrations of ARTS and DHA were determined by h.p.l.c. assay. Pharmacokinetic parameters were calculated by non-compartmental methods. The time to 50% parasite clearance (PCT50) was calculated by linear interpolation of parasite density determinations. Linear least squares and multiple linear regression analyses were used to evaluate pharmacokinetic-pharmacodynamic relationships. RESULTS: Following i.v. bolus, ARTS had a peak concentration of 29.5 microM (11 mg l[-1]), elimination t1/2 = 2.7 min, CL = 2.33 l h(-1) kg(-1) and V = 0.14 l kg(-1). The Cmax for DHA was 9.3 microM (2.64 mg l[-1]), t1/2 = 40 min, CL =0.75 l h(-1) kg(-1) and V = 0.76 l kg(-1). Following oral ARTS, relative bioavailability of DHA was 82%, Cmax was 2.6 microM (0.74 mg l[-1]), t1/2 = 39 min, and MAT = 67 min. Overall, the PCT50 and fever clearance time (FCT) were 6.5 h and 24 h, respectively. There was no correlation between PCT50 or FCT and AUC, Cmax or MRT for DHA. CONCLUSIONS: Despite rapid clearance of ARTS and DHA in patients with uncomplicated falciparum malaria, prompt parasite and fever clearance were achieved. High relative bioavailability of DHA following oral ARTS administration, and clinical outcomes comparable with those after i.v. ARTS, support the use of the oral formulation in the primary care setting.
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Antimaláricos/farmacocinética , Artemisininas , Malaria Falciparum/tratamiento farmacológico , Sesquiterpenos/farmacocinética , Administración Oral , Adulto , Antimaláricos/administración & dosificación , Antimaláricos/sangre , Antimaláricos/uso terapéutico , Artesunato , Femenino , Humanos , Inyecciones Intravenosas , Malaria Falciparum/epidemiología , Masculino , Valores de Referencia , Sesquiterpenos/sangre , Sesquiterpenos/uso terapéutico , Factores de Tiempo , Vietnam/epidemiologíaRESUMEN
We report a 57-year-old man with falciparum malaria contracted in Kenya who presented with a three-day history of symptoms. Despite prompt treatment with quinine and artesunate and rapid clearing of the parasitaemia, he developed multiple complications and died 28 days after presentation. This case illustrates the potential for malaria to be fatal despite appropriate treatment and is one of the first reports of the use of artesunate in a hospital in a developed country.
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Antimaláricos/uso terapéutico , Artemisininas , Malaria Falciparum/tratamiento farmacológico , Quinina/uso terapéutico , Sesquiterpenos/uso terapéutico , Artesunato , Resultado Fatal , Humanos , Kenia , Malaria Falciparum/complicaciones , Malaria Falciparum/parasitología , Masculino , Persona de Mediana Edad , Índice de Severidad de la Enfermedad , Factores de Tiempo , Viaje , Australia Occidental/etnologíaRESUMEN
1. To assess neurological, cardiovascular, metabolic and other side-effects of mefloquine given in conventional prophylactic dose to healthy volunteers, a double-blind, randomized, placebo-controlled trial was conducted. In addition, the identity of the active drug was concealed until the end of the trial. 2. A total of 106 healthy adults were recruited, of whom 95 (mean age 24 years; 45% males) completed the full study protocol. 3. Subjects had a baseline assessment, received placebo as first dose, were randomized to mefloquine 250 mg or placebo weekly for 4 weeks starting a week later, and were reassessed after the 2nd and 4th active/placebo doses. Subjects kept a daily symptom diary from 2 weeks before until 2 weeks after the dosing period. 4. Plasma mefloquine assay suggested compliance in all 46 subjects allocated active treatment (week 5 mean +/- s.d.; 2.35 +/- 0.94 mumol l-1. Mefloquine did not alter calcium homoeostasis but produced a mean 0.5 mmol l-1 fall in serum glucose over the study period (P < 0.001) and relative hyperinsulinaemia. Symbol digit modalities, and digit forwards and backwards test scores, were similar in active and placebo groups across the three assessments, as were lying/standing blood pressure and high-tone hearing loss. Electrocardiographic QTc interval prolongation and diarrhoea were mild but transient side-effects of mefloquine (P < 0.01). Neurological symptoms were comparable in the two groups throughout the study. There was no evidence of drug toxicity in 11 subjects who withdrew. 5. Mefloquine prophylaxis does not appear to produce low-grade but debilitating neurological symptoms or to alter the results of sensitive tests of cerebral function. However, there may be situations in which mefloquine might contribute to hypoglycaemia and cardiac dysrhythmias.
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Antimaláricos/efectos adversos , Sistema Cardiovascular/efectos de los fármacos , Mefloquina/efectos adversos , Sistema Nervioso/efectos de los fármacos , Adulto , Calcio/metabolismo , Método Doble Ciego , Femenino , Homeostasis , Humanos , Masculino , Cooperación del Paciente , Placebos , Psicometría , Valores de ReferenciaRESUMEN
A novel solid-phase extraction and a robust high-performance liquid chromatographic (HPLC) separation procedure for artesunate and alpha- and beta-dihydroartemisinin, using post-column alkali decomposition and UV detection is described. Extraction was performed with Bond-Elut Phenyl solid-phase extraction cartridges and analysis by HPLC was carried out using a Waters Symmetry C8 5-microns 150 x 3.9 mm I.D. column. The mobile phase was 50% acetonitrile in 0.1 M acetate buffer (pH 4.8) delivered at a flow-rate of 0.7 ml/min. The column eluate was mixed with 1.2 M potassium hydroxide in 90% methanol delivered at 0.3 ml/min, in a 1-ml reaction coil at 69 degrees C, to form UV-absorbing chromophores which were detected at 290 nm. The recovery of all analytes was greater than 80%. There was no significant difference in the peak-area ratio of alpha- and beta-dihydroartemisinin in plasma. Preliminary pharmacokinetic data from six adult Vietnamese patients who received 120 mg of artesunate by intravenous injection for the treatment of acute falciparum malaria are presented. Despite limited data, the mean half-life of artesunate was approximately 3.5 min while that for dihydroartemisinin was 34 min. These data confirm the relatively rapid clearance of both artesunate and its principle active metabolite, dihydroartemisinin.
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Antimaláricos/uso terapéutico , Artemisininas , Malaria Falciparum/tratamiento farmacológico , Sesquiterpenos/uso terapéutico , Artesunato , Cromatografía Líquida de Alta Presión , Humanos , Isomerismo , Reproducibilidad de los Resultados , Sesquiterpenos/sangre , Sesquiterpenos/química , Espectrofotometría UltravioletaRESUMEN
Artesunate, the only artemisinin analogue that can be given intravenously, produces rapid parasite and fever clearance in falciparum malaria. A significant therapeutic problem is a high, late recrudescence rate, probably due to short half-lives of both artesunate and its active metabolite dihydroartemisinin relative to conventional dosing intervals. One method of extending the duration of action of artesunate could be to administer the drug by infusion rather than bolus injection, provided that it is chemically stable at ambient temperature. Artesunate was found to be stable in 0.9% w/v sodium chloride at 9 degrees C, 23 degrees C and 36.5 degrees C for 130, 10.6 and 1.6 h, respectively. Interpolating from an Arrhenius plot, artesunate should be stable for approximately 4 h at 30 degrees C, a temperature representative of ambient conditions in tropical countries. Exposure to light did not affect the degradation rate. Single compartment pharmacokinetic modelling was used to evaluate potential differences in artesunate and dihydroartemisinin plasma concentrations following administration of artesunate by intravenous bolus or infusion. A bolus injection of artesunate at a dose of 4 mg kg-1 gives a peak concentration of 5.3 mg L-1, falling to 0.005 mg L-1 at 5 h. The same dose infused over 4 h results in a peak concentration of 0.92 mg L-1, falling to 0.005 mg L-1 at 8 h. Simultaneous modelling of dihydroartemisinin showed that while its peak plasma concentration was reduced by 27% and the peak delayed by 2.5 h following artesunate administration by infusion, substantially higher concentrations were maintained compared with those predicted after bolus artesunate. These data indicate that artesunate can be administered as a high-dose intravenous infusion, thus avoiding high plasma concentrations. This strategy also has the potential to prolong the duration of antimalarial effect and reduce toxicity, and consequently improve clinical outcome in seriously ill patients.
Asunto(s)
Antimaláricos/farmacocinética , Artemisininas , Sesquiterpenos/sangre , Sesquiterpenos/farmacocinética , Antimaláricos/sangre , Artesunato , Cromatografía Líquida de Alta Presión , Estabilidad de Medicamentos , Almacenaje de Medicamentos/normas , Semivida , Infusiones Intravenosas , Inyecciones Intravenosas , Estándares de Referencia , Sesquiterpenos/administración & dosificación , Cloruro de Sodio/química , Estadística como Asunto , Jeringas , TemperaturaRESUMEN
1. The mechanism of the interaction between ciprofloxacin and theophylline was investigated in nine healthy subjects. 2. Subjects were given a single oral dose of theophylline (3.4 mg kg-1), before and after 60 h of ciprofloxacin therapy at a dose of 500 mg twice daily. 3. Ciprofloxacin reduced the oral clearance of theophylline by 19% (-7.73 +/- 6.42 ml kg-1 h-1 (95% confidence limits -12.66, -2.79)). Some subjects (group A, n = 4) showed little decrease in clearance (mean 4.4%; -1.6 +/- 0.7 ml kg-1 h-1 (-2.6, 0.5)), whereas others (group B, n = 5) showed a marked decrease (mean 30%; -12.7 +/- 3.7 ml kg-1 h-1 (-17.2, -8.1)). 4. Comparing groups A and B, the decrease in oral clearance of theophylline in group B could not be ascribed to differences in the AUC of ciprofloxacin. Group A subjects showed only slight inhibition of 1-demethylation (-12.8 +/- 5.5% (-21.5, -4.0)), while group B subjects showed a significantly greater inhibition of 1-demethylation (-49.9 +/- 9.8% (-62.1, -37.7)), 3-demethylation (-44.8 +/- 8.6% (-55.4, -34.1)) and 8-hydroxylation (-27.0 +/- 3.7% (-31.6, -22.4)). 5. The results suggest that inter-individual variability in the inhibition of theophylline metabolism by ciprofloxacin can be attributed to inter-individual differences in the level of CYP1A2 expression and/or in the degree of inhibition of hepatic CYP1A2 and CYP3A4. 6. The interaction between ciprofloxacin and theophylline can be clinically significant.(ABSTRACT TRUNCATED AT 250 WORDS)
Asunto(s)
Ciprofloxacina/farmacología , Teofilina/farmacocinética , Administración Oral , Adolescente , Adulto , Cromatografía Líquida de Alta Presión , Ciprofloxacina/administración & dosificación , Citocromo P-450 CYP1A2 , Citocromo P-450 CYP3A , Inhibidores Enzimáticos del Citocromo P-450 , Sistema Enzimático del Citocromo P-450/biosíntesis , Interacciones Farmacológicas , Femenino , Polarización de Fluorescencia , Humanos , Masculino , Tasa de Depuración Metabólica/efectos de los fármacos , Oxigenasas de Función Mixta/antagonistas & inhibidores , Oxigenasas de Función Mixta/biosíntesis , Oxidorreductasas/antagonistas & inhibidores , Oxidorreductasas/biosíntesis , Teofilina/administración & dosificación , Teofilina/orinaRESUMEN
OBJECTIVES: To assess patient knowledge about asthma management and to assess the risk of asthma-associated morbidity in patients admitted to hospital with acute severe asthma. SUBJECTS AND SETTING: Patients admitted to Fremantle Hospital with a primary diagnosis of acute severe asthma from July to September 1992. RESULTS: Bronchodilator therapy has been used for more than 12 months by all 25 previously diagnosed asthmatics, with 88% knowing that the drug was a bronchodilator. Corticosteroid therapy had been used by 84% of patients but only 52% of these knew that it was anti-inflammatory or "preventive" medication. Sixty per cent of patients did not recall seeing National Asthma Campaign advertisements. Twenty-three patients (88%) were classified as being at high risk of morbidity. CONCLUSIONS: The level of knowledge about asthma management in patients admitted to this hospital is poor. Most patients are at high risk of asthma-associated morbidity.