Effect of nitric oxide-cyclic GMP-K+ channel pathway blockers, naloxone and metformin, on the antinociception induced by the diuretic pamabrom.

Pamabrom is a diuretic that is effective in treating premenstrual syndrome and primary dysmenorrhea. The aim of this study was to examine the effect of metformin and modulators of the opioid receptor-nitric oxide (NO)-cyclic guanosine monophosphate (cGMP)-K+ channel pathway on the local antinociception induced by pamabrom. The rat paw 1% formalin test was used to assess the effects. Rats were treated with local administration of pamabrom (200-800 µg/paw) or indomethacin (200-800 µg/paw). The antinociception of pamabrom or indomethacin was evaluated with and without the local pretreatment of the blockers. Local administration of pamabrom and indomethacin produced dose-dependent antinociception during the second phase of the test. Local pretreatment of the paws with naloxone (50 µg/paw), l-nitro-arginine methyl ester (10-100 µg/paw), or 1H-(1,2,4)-oxadiazolo[4,2-a]quinoxalin-1-one (10-100 µg/paw) reverted the antinociception induced by local pamabrom, but not of indomethacin. Similarly, the K+ channel blockers glibenclamide, glipizide, 4-aminopyridine, tetraethylammonium, charybdotoxin, or apamin reverted the pamabrom-induced antinociception, but not of indomethacin. Metformin significantly blocked the antinociception of pamabrom and indomethacin. Our data suggest that pamabrom could activate the opioid receptor-NO-cGMP-K+ channel pathway to produce its peripheral antinociception in the formalin test. Likewise, a biguanide-dependent mechanism could be activated by pamabrom and indomethacin to generate antinociception.

Erythema multiforme secondary to dimenhydrinate in a patient with previous similar reactions to pamabrom.

OBJECTIVE: To report a case of erythema multiforme secondary to dimenhydrinate and pamabrom cross-sensitivity. CASE SUMMARY: A 22-year-old Chinese female presented with a complaint of lip mucosal ulceration with necrosis and stomatitis, worsening over the past 24 hours and associated with reduced oral intake and incomplete opening of the mouth. Presentation was accompanied by a generalized rash and genital mucosal involvement. The only new systemically ingested agent was dimenhydrinate approximately 4 days prior to admission. She had no significant medical history, but was labeled to be allergic to acetaminophen. She had a positive history of 2 similar presentations secondary to Panadol Menstrual (acetaminophen and pamabrom), once 3 years ago and again 5 months prior to the current admission. An objective causality assessment revealed that the adverse drug event was "probable" to dimenhydrinate. A detailed history revealed a negative drug challenge to acetaminophen. She had previously taken plain acetaminophen and Beserol (acetaminophen and chlormezanone) with no reaction. DISCUSSION: A comprehensive history taking facilitated the diagnosis of erythema multiforme secondary to dimenhydrinate without the need to perform invasive testing, and the removal of erroneous allergy labeling to acetaminophen. Dimenhydrinate and pamabron both contain theophylline-related structures in their chemical composition. Similar reactions to pamabrom strongly suggested cross-sensitivity to theophylline-related structures. CONCLUSIONS: To our knowledge, this is the first report of erythema multiforme due to dimenhydrinate with pamabron cross-sensitivity. We recommend that comprehensive medication-history taking be carried out for all drug-allergy patients to ensure greater informed decision making when choosing medications to use for that patient in the future.

Naproxen, paracetamol and pamabrom versus paracetamol, pyrilamine and pamabrom in primary dysmenorrhea: a randomized, double-blind clinical trial. / Naproxeno, paracetamol y pamabrom versus paracetamol, pirilamina y pamabrom en dismenorrea primaria: estudio aleatorizado, doble ciego.

INTRODUCTION: Dysmenorrhea is caused by the discharge of prostaglandins into the uterine tissue; therefore, non-steroidal anti-inflammatory drugs (NSAIDs) are the established initial therapy for dysmenorrhea. Dysmenorrhea therapy may include the administration of drug monotherapy or combination therapy. However, clinical scientific evidence on the efficacy of medications with two or three drugs combined is scarce or nonexistent. OBJECTIVE: To evaluate and compare the efficacy and safety of two oral fixed-dose combinations for the relief of the symptoms of primary dysmenorrhea among Mexican women. One of the combinations is widely used in Mexico (paracetamol, pyrilamine and pamabrom) and the selected comparison was a medication with naproxen sodium, paracetamol and pamabrom based on the pathophysiology of primary dysmenorrhea. METHODS: This was a single-centre, double blind, experimental, parallel group, randomized trial. Female patients with primary dysmenorrhea, older than 17 years and with pain intensity greater than 45 mm on a visual analogue scale, were included. The patients were then randomized to receive tablets with naproxen sodium, paracetamol and pamabrom or tablets with paracetamol, pyrilamine and pamabrom for one menstrual cycle. Patient evaluations of symptomatology and pain intensity were recorded throughout one menstrual period. Descriptive and inferential statistical analyses were utilized. RESULTS: An intention-to-treat population of 91 women, with a mean age of 21.3 ± 3.2 years, received paracetamol, pyrilamine and pamabrom tablets, and 98 participants, with a mean age of 21.0 ± 3.2 years, received naproxen sodium, paracetamol and pamabrom tablets. The participants’ assessments of pain on the Visual Analogue Scale during the menstrual cycle demonstrated a significant reduction in both treatment groups (p<0.05). There is no significant difference in efficacy between both groups (p>0.05). CONCLUSIONS: The results showed that both drug combinations were not different in reducing dysmenorrheic pain. Likewise, both treatments were well tolerated. Therefore, both treatments may be used for the treatment of primary dysmenorrhea.

INTRODUCCIÓN: La dismenorrea primaria es causada por la descarga de las prostaglandinas en el tejido uterino. Por lo tanto, los fármacos antiinflamatorios no esteroideos son la terapia inicial para la dismenorrea. El tratamiento para la dismenorrea puede incluir la administración de monoterapia o la combinación de fármacos. Sin embargo, la evidencia clínica científica sobre la eficacia de los medicamentos con dos o tres fármacos combinados es escasa o ausente. OBJETIVO: Evaluar y comparar la eficacia y seguridad de dos combinaciones, en dosis fija y oral para el alivio de los síntomas de la dismenorrea primaria en mujeres mexicanas. Basados en la fisiopatología de la dismenorrea primaria, se utilizó una combinación comercializada en México de paracetamol, pirilamina y pamabrom. El comparador seleccionado fue un medicamento que contiene naproxeno sódico, paracetamol y pamabrom. MÉTODOS: Se realizó un estudio en un solo centro, a doble ciego, experimental, paralelo y aleatorizado. Las pacientes con dismenorrea primaria que se incluyeron fueron mayores de 17 años de edad y con una intensidad del dolor mayor a 45 milímetros en una escala visual analógica. Las pacientes fueron aleatorizadas para recibir tabletas con naproxeno sódico, paracetamol y pamabrom o tabletas con paracetamol, pirilamina y pamabrom para un ciclo menstrual. Se evaluó la intensidad de la sintomatología y el dolor de las pacientes a lo largo de un período menstrual. Se utilizó análisis estadístico descriptivo e inferencial. RESULTADOS: Se incluyó una población con intención de tratar de 91 mujeres, con una edad media de 21,3 ± 3,2 años la cual recibió tabletas de paracetamol, pirilamina y pamabrom. Otras 98 participantes, con una edad media de 21,0 ± 3,2 años, recibieron tabletas de naproxeno sódico, paracetamol y pamabrom. Las evaluaciones de dolor de las participantes con la escala visual analógica durante el ciclo menstrual demostraron una reducción significativa en ambos grupos de tratamiento (p<0,05). No hubo diferencia significativa en la eficacia entre los dos grupos (p>0,05). CONCLUSIONES: Los resultados mostraron que ambas combinaciones de fármacos no fueron diferentes en reducir el dolor dismenorreico. Del mismo modo, ambos tratamientos fueron bien tolerados. Por lo tanto, ambos tratamientos se pueden utilizar para el tratamiento de la dismenorrea primaria.

Dexketoprofen más pamabrom versus acetaminofen en dismenorrea primaria: estudio controlado, randomizado, doble ciego, multicéntrico / Dexketoprofen plus pamabrom versus acetaminophen in primary dysmenorrhea: a controlled, randomized, double-blind, multicenter study

RESUMEN Introducción: se sabe que las concentraciones plasmáticas de hormona antidiurética o vasopresina son más altas en las mujeres con dismenorrea primaria (DiPr) y podría ser causa de retención de agua con signos y síntomas concomitantes que agravan su cuadro clínico. La monoterapia con AINEs en ocasiones alcanza solo un alivio parcial porque no incide sobre la vasopresina. Objetivo: evaluar la eficacia y tolerabilidad del dexketoprofeno + pamabrom en la DiPr tomando como referencia el acetaminofén. Materiales y métodos: estudio doble ciego, controlado, randomizado, en pacientes con DiPr asignados al azar. Fueron aleatorizadas 172 pacientes, 86 en cada grupo 1) Grupo casos (DP): dexketoprofeno + pamabrom o 2) Grupo control (AC): acetaminofén. Se evaluó la evolución de la intensidad del dolor, el alivio del dolor, la gravedad de otros síntomas presentes y la satisfacción global del médico y paciente. Se registró las reacciones adversas. Resultados: la disminución de la intensidad del dolor, de los síntomas acompañantes y el alivio del dolor evaluados por la EVA, la PID, la SPID, el PAR y el TOTPAR respectivamente es mayor y más rápida de modo significativo en todos los tiempos para la combinación DP. Las reacciones adversas fueron mínimas. La satisfacción global de pacientes y médicos respecto al tratamiento es significativa a favor de la combinación DP. Conclusiones: dexketoprofeno + pamabrom es significativamente más eficaz y rápido en el control del dolor y otros síntomas presentes en la dismenorrea primaria que acetaminofén demostrando la validez de añadir un diurético suave a un AINE para incrementar su eficacia. El tratamiento DP es bien tolerado (AU).

ABSTRACT Background: It is known that plasma concentrations of antidiuretic hormone or vasopressin are higher in women with primary dysmenorrhea (DiPr) and could cause water retention with concomitant signs and symptoms that aggravate the illness. Monotherapy with NSAIDs sometimes achieves only partial relief because it does not affect vasopressin. Objective: The aim was to evaluate the efficacy and tolerability of dexketoprofen + pamabrom in DiPr taking as reference acetaminophen. Materials and methods: Double-blind, controlled, randomized study in patients with DiPr random to 1) Case group (PD): dexketoprofen + pamabrom or 2) Control group (CA): acetaminophen. The evolution of pain intensity, pain relief, severity of other present symptoms and overall satisfaction of the doctor and patient were evaluated. Adverse reactions were recorded. Results: 172 patients were randomized, 86 in each group. The decrease in pain intensity, accompanying symptoms and pain relief evaluated by VAS, PID, SPID, PAR and TOTPAR respectively is significantly greater and faster at all times for the combination DP. Adverse reactions were minimal. The overall satisfaction of patients and doctors regarding treatment is significant in favor of the DP combination. Conclusions: Dexketoprofen + pamabrom is significantly more effective and faster in the control of pain and other symptoms present in primary dysmenorrhea than acetaminophen demonstrating the validity of adding a mild diuretic to an NSAID to increase its effectiveness. DP treatment is well tolerated (AU).

HPTLC and RP-HPLC methods for simultaneous determination of Paracetamol and Pamabrom in presence of their potential impurities.

Two chromatgraphic methods were developed for determination of Paracetamol (PCM) and Pamabrom (PAM) in presence of P-aminophenol (PAP) and Theophylline (THEO) as potential impurities of both drugs respectively. First method is HPTLC which depends on separation and quantitation of the studied drugs on aluminum plates pre-coated with silica gel 60 F254 as a stationary phase using chloroform:methanol:ethyl acetate:glacial acetic acid (8:0.8:0.6:0.2, v/v/v/v) as mobile phase followed by densitometric measurement of the bands at 254 nm. Second method is RP-HPLC which comprises separation of the studied drugs on a Phenomenex C8 column by gradient elution using mobile phase consisting of sodium dihydrogen phosphate buffer (0.05 M): methanol:acetonitrile (85:10:5, v/v/v) at a flow rate of 1 mL/min for first 7.5 min and (70:20:10, v/v/v) at a flow rate of 1.5 mL/min for the next 5 min. The proposed methods were successfully applied for determination of the potential impurities of PCM and PAM after resolving them from the pure drugs. The developed methods have been validated and proved to meet the requirements delineated by ICH guidelines with respect to linearity, accuracy, precision, specificity and robustness. The validated methods were successfully applied for determination of the studied drugs in their pharmaceutical formulation. The results were statistically compared to those obtained by the reported RP-HPLC method where no significant difference was found; indicating the ability of proposed methods to be used for routine quality control analysis of these drugs.

Development and Validation of Stability-indicating RP-HPLC Method for Estimation of Pamabrom in Tablets.

The present study depicts the development of a validated RP-HPLC method for the determination of the pamabrom in presence of degradation products or other pharmaceutical excipients. Stress study was performed on pamabrom and it was found that it degrade sufficiently in acidic, alkali and oxidative condition but less degradation was found in thermal and photolytic condition. The separation was carried out on Enable G 120 A(0) (250×4.6 mm, 5 µ) column having particle size 5 µ using methanol: water (75:25 v/v) with pH 4.0 adjusted with ortho phosphoric acid as mobile phase at flow rate of 1 ml/min. The wavelength of the detection was 280nm. A retention time (Rt) nearly 3.9 min was observed. The calibration curve for pamabrom was linear (r (2) = 0.9997) from range of 10-60 µg/ml with limit of detection and limit of quantification of 1.41 µg/ml and 4.28 µg/ml, respectively. Analytical validation parameter such as selectivity, specificity, linearity, accuracy and precision were evaluated and relative standard deviation value for all the key parameters were less than 2.0%. The recovery of the drug after standard addition was found to be 101.35%. Thus, the developed RP-HPLC method was found to be suitable for the determination of pamabrom in bulk as well as stability samples of tablets containing various excipients.

RP-LC and TLC Densitometric Determination of Paracetamol and Pamabrom in Presence of Hazardous Impurity of Paracetamol and Application to Pharmaceuticals.

Two simple, accurate and reproducible methods were developed and validated for the simultaneous determination of paracetamol (PARA) and pamabrom (PAMB) in pure form and in tablets. The first method was based on reserved-phase high-performance liquid chromatography, on a Thermo Hypersil ODS column using methanol:0.01 M sodium hexane sulfonate:formic acid (67.5:212.5:1 v/v/v) as the mobile phase. The flow rate was 2 mL/min and the column temperature was adjusted to 35 °C. Quantification was achieved with UV detection at 277 nm over concentration range of 100-600 and 4-24 µg/mL, with mean percentage recoveries were found to be 99.90 ± 0.586 and 99.26 ± 0.901 for PARA and PAMB, respectively. The second method was based on thin-layer chromatography separation of PARA and PAMB followed by densitometric measurement of the spots at 254 nm and 277 nm for PARA and PAMB respectively. Separation was carried out on aluminum sheet of silica gel 60F254 using dichloromethane:methanol:glacial acetic acid (7.5:1:0.5 v/v/v) as the mobile phase over concentration range of 1-10 and 0.32-3.20 µg per spot, with mean percentage recovery of 100.52 ± 1.332 and 99.71 ± 1.478 for PARA and PAMB, respectively. The methods retained their accuracy in presence of up to 50% of P-aminophenol and could be successfully applied in tablets.