Analysis of captopril and hydrochlorothiazide combination tablet formulations by liquid chromatography

A reverse-phase, high-performance liquid chromatographic (HPLC) procedure was developed for the simultaneous assay of captopril and hydrochlorothiazide in a combination tablet formulation. Gradient elution was used to quantify these two drugs, as well as the oxidized form of captopril, the disulfide. Tablets were extracted with methanol and, after centrifugation, were chromatographed. Initially, a methanol-0.05% aqueous phosphoric acid (25:75, v/v) solution was pumped at 2 mL/min into a phenyl column. After 8 min, the flow rate was increased to 4.5 mL/min and the methanol content of the mobile phase was increased to 45% to elute the disulfide. Detection was at 210 nm. Linearity and repeatability of all constituents were satisfactory. The hydrolytic degradation product of hydrochlorothiazide, 4-amino-6-chloro-1,3-benzene disulfonamide (also called the disulfonamide ), could be resolved in test solutions but was not visible in chromatograms of tablets carried through the gradient procedure even after storage at elevated temperatures for prolonged time periods prior to assay. The method can be automated.     

Biopharmaceutical characteristics of a new propranolol/ hydrochlorothiazide tablet combination

Experiments have been carried out in dogs and man to determine the effect of hydrochlorothiazide (HCT) on the pharmacokinetics of propranlol and to evaluate the bioavailability of two dosage forms containing both propranolol and HCT (40/25 and 80/25 mg, respectively). In adult male beagles, 50 mg of HCT had no apparent effect on AUC, C_max, T_max, and T_1/2 of propranolol administered concurrently. In man, INDERIDE® (40/25 mg) and INDERIDE® (80/25 mg) were shown to be similar in bioavailability to the reference formulations, i.e. the same amount of drugs administered as the separate tablets of INDERAL® plus HYDRODIURIL®.     

Comparative antihypertensive effects of enalapril maleate and hydrochlorothiazide, alone and in combination

Enalapril maleate is an investigational oral prodrug whose hydrolyzed diacid metabolite is a potent angiotensin-converting enzyme inhibitor. Fourteen patients with mild to moderate hypertension were evaluated after receiving placebo, and two weeks of treatment with each of the following: enalapril maleate (20 mg b.i.d.), hydrochlorothiazide (25 mg b.i.d.), and the two in combination. In comparison to placebo, the magnitudes of the blood pressure reduction after enalapril and hydrochlorothiazide alone were comparable. The reduction in blood pressure following enalapril was evident throughout the 12-hour dosing interval. The combination of enalapril and hydrochlorothiazide resulted in a marked further reduction in blood pressure that was greater than that predicted from the responses to the individual drugs (P less than 0.05). Biochemical parameters confirmed inhibition of angiotensin-converting enzyme during enalapril treatment; serum angiotensin-converting enzyme activity proved an excellent monitor of compliance. Enalapril was generally well tolerated. Adverse effects included symptomatic hypotension in three patients when enalapril was first added to hydrochlorothiazide and hyperesthesia of the oral mucosa without a loss of taste in one patient on enalapril. Enalapril maleate alone and especially in combination with hydrochlorothiazide appears to be an effective, well-tolerated converting enzyme inhibitor with at least a 12-hour duration of action.     

Safety and antihypertensive efficacy of carvedilol and atenolol alone and in combination with hydrochlorothiazide

Carvedilol has been shown to be effective and safe in patients with essential hypertension when given as monotherapy. In this double-blind, randomized, group-comparative study, 2 groups of 59 patients with mild to moderate essential hypertension [median supine systolic/diastolic blood pressure at baseline (SBP/DBP), 168/105 mm Hg] were treated with either 25 mg carvedilol once daily (o. d.) or 50 mg atenolol o. d. for 4 weeks. Responders at 4 weeks (DBP, < 90=" mmhg)=" terminated=" the=" study.=" nonresponders=" continued=" the=" study.=" hydrochlorothiazide=" (hctz)=" was=" added=" at=" 25=" mg=" o.=" d.=" for=" a=" further=" 6=" weeks.=" the=" median=" blood=" pressure=" decreased=" under=" monotherapy=" with=" carvedilol=">n = 59) from 167/105 at baseline to 155/94 mmHg after 4 weeks, and in the atenolol group (n=59) it decreased from 168/105 to 162/97 mmHg. The patients who received carvedilol in combination with HCTZ and were evaluated for efficacy (n = 38) showed a decrease in SBP/DBP from 156/97 at the end of monotherapy to 145/88 mmHg after 10 weeks; the combination of atenolol with HCTZ (n = 44) reduced BP from 162/97 to 147/88. Both carvedilol and atenolol were safe when given either alone or in combination with HCTZ. In conclusion, after long-term administration, 25 mg carvedilol o. d. and 50 mg atenolol o. d. significantly reduced both SBP and DBP over 24 h. The addition of HCTZ led to a further increase in antihypertensive efficacy. Combined treatment with carvedilol or atenolol and HCTZ was very well tolerated, without hypotensive events or relevant changes in objective safety parameters.     

Pharmacokinetic comparison of a combination tablet of enalapril and hydrochlorothiazide with enalapril and hydrochlorothiazide tablets administered together and separately

Enalapril and hydrochlorothiazide (HCT) are established single agent treatments for mild hypertension and cardiac failure and are a potent combination in more severe or resistant cases. We have compared the pharmacokinetics of enalaprilat (the active metabolite of enalapril) and HCT in a four-way comparison of a combination tablet of enalapril (10 mg)/HCT (25 mg) with a single dose of an enalapril tablet (10 mg), a single dose of a HCT tablet (25 mg) and simultaneous administration of separate tablets of enalapril (10 mg) and HCT (25 mg) in normotensive volunteers (n = 12, 21-26 years). Each subject received all four treatments and the study was conducted as a randomized, latin square, open design with at least 1 week washout between studies. Overall, HCT was bioequivalent under all conditions and enalaprilat was bioequivalent when given in combination with HCT either as one tablet or as two separate tablets. However, when given with HCT, the mean AUC and Cmax of enalaprilat were reduced up to 20 per cent compared with enalapril administered alone. This is unlikely to be of clinical significance as the differences did not reach statistical significance and the total enalaprilat excreted in the urine over 96 h was similar after all treatments.     

The potential benefits of a garlic and hydrochlorothiazide combination as antihypertensive and cardioprotective in rats

The purpose of the present study was to investigate the protective effects of combined therapy of garlic homogenate and hydrochlorothiazide (HCTZ) in animals with hypertension and myocardial damage. Three weeks of high fructose (10% w/v) in fluid to albino rats resulted in hypertension. They were subsequently administered garlic (125, 250 and 500 mg/kg, 3 weeks in separate groups) and HCTZ (10 mg/kg, 6th week) once daily in their respective groups. At the end of 6 weeks, myocardial damage was induced by subcutaneous administration of isoproterenol (175 mg/kg) for 2 consecutive days. The results showed that garlic and HCTZ increase the lactate dehydrogenase, creatinine phosphokinase, superoxide dismutase and catalase activities in heart homogenate when used concurrently or separately. Further, restoration of normal values in fluid/food intake, body weight, systolic blood pressure, cholesterol, triglycerides, glucose and histopathological scores were observed in all treated groups. Furthermore, histological disturbances and hypertension were significantly ameliorated in treated animals. Moreover, moderate dose of garlic was more effective than low dose, while a high dose of garlic was least effective in correcting electrocardiographic changes. Thus it is concluded that garlic in moderate dose (250 mg/kg) with added HCTZ possesses synergistic cardioprotective and antihypertensive properties against fructose- and isoproterenol-induced toxicities.     

Efficacy and safety of triple antihypertensive therapy with the olmesartan/amlodipine/hydrochlorothiazide combination

Background: European hypertension guidelines estimate that up to 15-20% of hypertensive patients are not controlled on a dual antihypertensive combination and require three or more different antihypertensive drug classes to achieve blood pressure (BP) control. Objective: This study in patients with moderate-to-severe hypertension assessed the efficacy and safety of adding hydrochlorothiazide (HCTZ) 12.5?mg and 25?mg to a range of olmesartan medoxomil (OLM)/amlodipine (AML) doses. Study Design: This phase III, multicentre study had a randomized, double-blind, parallel-group design that included a double-blind safety run-in and a double-blind treatment period. Intervention: Enrolled patients were screened and previous therapy was discontinued if required. During a 2-week, double-blind, safety run-in period (Weeks 0-2), patients were randomized to receive placebo, OLM/AML 20?mg/5?mg, OLM/AML 40?mg/5?mg or OLM/AML 40?mg/10?mg. During an 8-week, double-blind treatment period (Weeks 3-10), patients were allocated to eight groups depending on their initial treatment. They were either randomized to continue with the same dose of OLM/AML, or have HCTZ 12.5?mg or 25?mg added to treatment. Main Outcome Measure: The primary endpoint was formulated before data collection began. It was the change in mean diastolic BP (DBP) from baseline to Week 10 in groups with HCTZ added to OLM/AML, compared with the corresponding dual OLM/AML therapy. Results: Of 3195 patients who were screened, 2690 were randomized. Patients in every triple OLM/AML/HCTZ group had significantly greater mean reductions in DBP (p?≤?0.032 for each comparison) and systolic BP (SBP) by Week 10 (p?≤?0.0034 for each comparison), compared with patients on the corresponding OLM/AML therapy dose. The significant improvements in DBP and SBP reduction with triple OLM/AML/HCTZ therapy, compared with dual OLM/AML therapy, were observed after 4 and 6 weeks of therapy. Patients in each triple therapy group also had a significantly higher rate of BP <140/90?mmHg threshold achievement (p?≤?0.05 for each treatment comparison), compared with the dual OLM/AML groups. In three of the OLM/AML/HCTZ groups (40?mg/5?mg/25?mg, 40?mg/10?mg/12.5?mg and 40?mg/10?mg/25?mg), BP <140/90?mmHg threshold achievement by Week 10 was over 70%. Across the triple and dual combination therapy groups, treatment was well tolerated and no safety concerns for either treatment were identified. Conclusion: Adding HCTZ to a range of OLM/AML dose combinations is well tolerated and improved BP control by significantly lowering DBP and SBP and significantly increasing BP threshold achievement in patients with moderate-to-severe hypertension. Clinical Trial Registration: Registered at ClinicalTrials.gov identifier as NCT00923091.     

Comparison of metoprolol and hydrochlorothiazide as antihypertensive agents

Summary A crossover comparison of metoprolol and hydrochlorothiazide has been performed in 20 patients with mild hypertension. Both drugs caused almost identical statistically significant reduction in blood pressure of about 20 mm Hg systolic and 15 mm Hg diastolic. The side effects during active therapy were few and mild, but 5 patients experienced subjective symptoms during the first few days following abrupt withdrawal of metoprolol, namely general malaise, palpitations, headache, sweating and tremor. The symptoms were more pronounced in the standing postition and disappeared at once on resumption of -blocker therapy, or gradually over 5 – 7 days when placebo tablets were given. In 11 of the 20 patients hydrochlorothiazide produced subnormal serum potassium levels and potassium supplements were given. The serum uric acid level was also significantly increased during hydrochlorothiazide treatment.     

Pharmacokinetics,safety, and antihypertensive efficacy of losartan in combination with hydrochlorothiazide in hypertensive patients with renal impairment

The pharmacokinetics and pharmacodynamics of 7 days of treatment with losartan 50 mg/hydrochlorothiazide 12.5 mg were evaluated in 14 patients with normal renal function and in 12 patients with mild to moderate renal impairment. The efficacy of losartan 50 mg/hydrochlorothiazide 12.5 mg titrated to losartan 100 mg/hydrochlorothiazide 25 mg was examined in 32 hypertensive patients with mild to moderate renal impairment who were treated for 12 weeks. Safety was assessed in both studies by the incidence of adverse experiences. After 7 days of treatment, the AUC for losartan, E-3174, and hydrochlorothiazide was slightly higher in patients with mild to moderate renal impairment, but the reduction in blood pressure (BP) after 7 days was not different between the two groups. The final (week 12) mean reductions in trough sitting diastolic and systolic BP were 15.0 +/- 7.1 mmHg (p < 0.01) and 20.8 +/- 16.7 mmHg (p < 0.01), respectively. There were no observed increases in drug-related adverse experiences in either study. Overall, the combination of losartan/hydrochlorothiazide was effective in lowering blood pressure and was well tolerated in patients with mild to moderate renal impairment.     

The comparative bioavailability of an extended-release niacin and lovastatin fixed dose combination tablet versus extended-release niacin tablet, lovastatin tablet and a combination of extended-release niacin tablet and lovastatin tablet

Lovastatin and extended-release (ER) niacin in a fixed dose combination (Advicor) is approved for the treatment of dyslipidemia. Since both drugs are extensively metabolized, this study investigated the bioavailability and pharmacokinetics of their co-administration following single-dose administration. In a 4-way crossover study 40 subjects received: two 1000/20 Advicor tablets (ADV), two 1000 mg niacin ER tablets (NSP), two 20mg lovastatin tablets (Mevacor; MEV), and two niacin ER 1000 mg tablets with two lovastatin 20mg tablets (NSP+MEV). Plasma was assayed for niacin, nicotinuric acid (NUA), lovastatin, lovastatin acid and HMGCoA reductase inhibition. Urine was assayed for niacin and its metabolites, NUA, N-methylnicotinamide and N-methyl-2pyridone-5-carboxamide. Least square mean ratios and 90% confidence intervals for C(max) and AUC((0-t)) were determined for NSP+MEV versus MEV or NSP, ADV versus MEV or NSP, and ADV versus NSP+MEV. Co-administration of niacin and lovastatin did not significantly influence C(max) and AUC((0-t)) of lovastatin, niacin, NUA and total urinary recovery of niacin and metabolites. A 22 to 25% decrease in lovastatin acid C(max) was observed while lovastatin acid AUC((0-t)) was not affected. The HMGCoA reductase inhibition C(max) and AUC((0-t)) were not affected indicating that the difference in lovastatin acid C(max) was not clinically relevant.     

Pharmacokinetics and pharmacodynamics of drospirenone-estradiol combination hormone therapy product coadministered with hydrochlorothiazide in hypertensive postmenopausal women

The effects of combination hormone therapy of drospirenone (DRSP), a novel progestin with antialdosterone properties, and 17beta-estradiol (E2) on hydrochlorothiazide (HCTZ) pharmacokinetics/pharmacodynamics versus placebo were investigated in a double-blind, placebo-controlled, crossover study. Thirty-six postmenopausal women with stage 1 hypertension maintained on 25 mg of HCTZ once daily were randomized to receive either 3 mg of DRSP/1 mg of E2 or placebo once daily for 4 weeks. Plasma HCTZ, serum DRSP, E2, potassium, aldosterone, and plasma renin activity were determined at baseline and after 4 weeks. Results showed that the combination of DRSP/E2 plus 25 mg of HCTZ is safe and well tolerated in hypertensive postmenopausal women. The pharmacokinetics of HCTZ were not affected by coadministration of DRSP/E2. The geometric mean ratios and 90% confidence intervals ([HCTZ + DRSP/E2]/[HCTZ + placebo]) for HCTZ (a) area under the serum/plasma concentration-time curve from 0 to 24 hours and (b) maximum plasma concentration were 101 (90.7, 112) and 103 (92.8, 115), respectively. In the HCTZ + DRSP/E2 group, serum potassium, aldosterone, and plasma renin activity all increased in a manner marginally consistent with a beneficial antialdosterone effect, counteracting the HCTZ-induced potassium loss and lowering both systolic and diastolic blood pressure. No dose adjustment is required when DRSP/E2 is added to antihypertensive therapy with HCTZ in hypertensive postmenopausal women.     

HPLC同时测定珍菊降压片中氢氯噻嗪与芦丁的含量

目的建立珍菊降压片中氢氯噻嗪与芦丁的HPLC测定法。方法C18柱（4．6mm×150mm,5μm）;乙腈-0．1％磷酸（15：85）为流动相,检测波长270nm,流速1．0ml·min^-1结果氢氯噻嗪与芦丁的加样回收率分别为98．79％、98．49％;线性范围分别为0．1635～0．8176μg、0．8304～4．1520μg。结论本方法简便可行,结果可靠,可用于珍菊降压片的质量控制。     

Identification and control of a degradation product in Avapro film-coated tablet: low dose formulation

A degradation product was formed during the long-term stability studies (LTSS) of the low dose formulation of Avapro film-coated tablet. The degradant was identified as the hydroxymethyl derivative (formaldehyde adduct) of the drug substance, irbesartan, based upon analysis with LC/MS, LC/MS/MS, and chromatographic comparison to the synthetic hydroxymethyl degradation product. Laboratory studies demonstrated that the interaction of individual excipients with the drug substance at elevated temperature and polyethylene glycol (PEG) used in the coating material, Opadry II White, leads to the generation of this formaldehyde adduct. Spiking of formaldehyde to the solution of drug substance gradually produced this impurity and the kinetics studies demonstrated that the reaction between formaldehyde and irbesartan is a second order reaction with a rate constant of 2.6 x 10(-4) M(-1)min(-1) at 25 degrees C in an aqueous media. The redevelopment of the formulation by eliminating PEG from the Opadry II White dry-blend system was enabled by understanding the formaldehyde adduct formation.     

Pharmacokinetics and pharmacodynamics of aliskiren/hydrochlorothiazide single-pill combination tablets and free combination of aliskiren and hydrochlorothiazide

Single-pill combinations (SPCs) of complementary antihypertensive agents provide patients with a simple and effective treatment regimen. To ensure that the efficacy and safety of an SPC is the same as that for the individual drugs administered together (free combination), SPC and free-combination formulations must be shown to be bioequivalent. Three open-label, randomized studies compared the pharmacokinetics of SPC tablets of the direct renin inhibitor aliskiren and hydrochlorothiazide (HCT), at doses of 150/25, 300/12.5, and 300/25 mg, with the corresponding free combinations in healthy volunteers. Data from 2 randomized, double-blinded studies of patients with hypertension were used to assess inhibition of plasma renin activity (PRA) by the aliskiren/HCT 300/25 mg SPC and the free combination. At all dose combinations, aliskiren and HCT systemic drug exposure was similar when administered as an SPC or free combination, indicating bioequivalence. Aliskiren/HCT 300/25 mg SPC inhibited PRA to the same extent as the free combination. HCT alone increased PRA through activation of the renin-angiotensin system; aliskiren prevented this diuretic-induced increase to the same extent when administered as the free combination or as the SPC. In conclusion, aliskiren/HCT SPCs are pharmacokinetically and pharmacodynamically bioequivalent to aliskiren and HCT in free combination.     

Bioavailability and disposition of metoprolol and hydrochlorothiazide combined in one tablet and of separate doses of hydrochlorothiazide.

1. The plasma levels and the urinary excretion of hydrochlorothiazide (HCT) have been studied after administration of single doses of 12.5 and 25 mg of the drug in solution and in combination with 100 mg of the selective beta 1-adrenoreceptor antagonist metoprolol in a rapidly dissolving tablet. 2. Metoprolol did not significantly influence the bioavailability or the time-course of HCT. 3. HCT had no significant effect on the time-course or the plasma levels of metoprolol. The average half-life, 4.4 +/- 0.9 h, is about the same as previously observed for separate doses of this drug. 4. It seems unlikely that repeated doses of the combination product studied will lead to biopharmaceutic or pharmacokinetic interactions of clinical importance.     

Pharmacokinetics of an oral frusemide/amiloride combination tablet

A randomized four-way crossover study was carried out in 12 healthy volunteers to investigate the pharmacokinetics of a new oral combination of frusemide (40 mg) and amiloride (5 mg), formulated as a single tablet. The experimental design of this bioequivalence study used commercially-available 40 mg frusemide tablets and 5 mg amiloride tablets as reference drugs, administered either separately or concomitantly. From a statistical analysis of plasma levels of frusemide and amiloride, no significant differences between the reference drugs alone and the combination tablet were seen in peak plasma levels, mean times to peak or mean areas under the plasma concentration-time curves (AUCs). The ratio of AUCs of the combination tablet to the reference drugs approached a limiting value many hours prior to complete elimination of the drug and hence reliable bioavailability comparisons were possible with blood sampling up to 24 hours post-dose.     

Tiapamil and hydrochlorothiazide: a double-blind comparison of two antihypertensive agents

Tiapamil is an investigational calcium-channel antagonist that is chemically related to verapamil. The antihypertensive efficacies of tiapamil and hydrochlorothiazide (HCTZ) were compared in a randomized double-blind trial. Thirty patients, age 44 to 80 years, with mild to moderate hypertension (World Health Organization stage I-II) entered and completed the study. Previous therapy, if any, was stopped for at least one week prior to study initiation, and patients received placebo tablets for two weeks. The participants were then given active medication, which was titrated for the next three weeks; HCTZ 25 to 50 mg bid or tiapamil 300 to 600 mg bid was given until supine diastolic blood pressure (BP) was no higher than 90 mm Hg or the ceiling dose was reached. Both drugs caused a significant reduction in systolic as well as in diastolic blood pressure (P less than .01). The reduction was seen in both the supine and erect position. The median decrease in supine systolic blood pressure from baseline to the end of treatment was 20 mm Hg in the tiapamil group and 27 mm Hg in the hydrochlorothiazide group, whereas the median decrease in supine diastolic blood pressure was 14 mm Hg and 18 mm Hg, respectively. The median difference in supine diastolic BP reduction after HCTZ and tiapamil administration was 3.8 mm Hg (not significant). There were no significant changes in heart rate. Dizziness occurred in one patient taking tiapamil and in three receiving HCTZ. One patient receiving HCTZ developed acute arthritis urica.(ABSTRACT TRUNCATED AT 250 WORDS)     

LC-MS/MS法同时测定厄贝沙坦和氢氯噻嗪血药浓度及厄贝沙坦氢氯噻嗪片的生物等效性研究

目的建立同时测定人血浆中厄贝沙坦和氢氯噻嗪血药浓度的液相色谱-质谱方法,并评价2种厄贝沙坦氢氯噻嗪片的生物等效性。方法以氯沙坦为内标,血浆样品经固相萃取后检测。Agilent Zorbax SB-C18(4.6 mm×50mm,1.8μm)为分析柱,以甲醇-乙腈-0.15%甲酸水溶液(40∶25∶35)为流动相,流速:0.3 m L·min^-1,用电喷雾离子化源(ESI),以负离子多离子反应监测(MRM)扫描方式进行监测。22例健康男性受试者随机于2个周期交叉口服相同剂量的厄贝沙坦氢氯噻嗪片受试药物或参比药物,考察其生物等效性。结果血浆中厄贝沙坦和氢氯噻嗪浓度分别在20.0~4000.0 ng·m L^-1和1.0~200.0 ng·m L^-1线性关系良好,线性回归方程分别为y=9.28×10^-2x-7.50×10^-2(r=0.999 2)和y=5.27×10-2x-2.99×10-2(r=0.998 8),日内和日间RSD均小于15%。受试药物相对于参比药物的厄贝沙坦和氢氯噻嗪的生物利用度分别为(107.4±19.9)%和(105.6±16.2)%。结论本方法简便、快速、灵敏度高,适用于人血浆中厄贝沙坦、氢氯噻嗪的浓度测定,可用于厄贝沙坦氢氯噻嗪片的人体生物等效性研究;2种药物生物等效。