Clinical safety, tolerability and efficacy of combination tolterodine/pilocarpine in patients with overactive bladder.

AIMS: The purpose of this study was to assess the safety, tolerability and impact on overactive bladder (OAB) symptoms of a novel combination of tolterodine immediate-release (IR) 2 mg and delayed-release pilocarpine 9 mg in patients with OAB. METHODS: Eligible patients with OAB were randomised to each of three treatments [tolterodine/pilocarpine (2/9 mg), tolterodine IR 2 mg or placebo] twice daily for 4 weeks in a double-blind, crossover fashion. At the end of the 12-week, double-blind treatment period, patients could enter an open-label extension during which they were re-randomised to either tolterodine/pilocarpine (3/13.5 mg) twice daily or tolterodine extended-release 4 mg once daily for 12 weeks. RESULTS: A total of 138 patients were randomised to double-blind medication. Both tolterodine/pilocarpine (2/9) and tolterodine IR 2 mg significantly reduced incontinence episodes and daily micturitions (p < 0.001 vs. placebo), with similar reductions in symptoms observed between active treatment groups. Tolterodine/pilocarpine (2/9) was associated with consistently lower Visual Analogue Scale (VAS) scores for all dry mouth parameters compared with tolterodine alone. Salivary flow over a 3 h period remained fairly constant after tolterodine/pilocarpine (2/9) administration, similar to placebo, but decreased markedly after administration of tolterodine alone. In the extension study, patients receiving tolterodine/pilocarpine (3/13.5) reported comparable dry mouth VAS scores to tolterodine extended-release alone without additional side effects or loss of efficacy. The combination was well tolerated, and the adverse effects observed were consistent with the known safety profiles of tolterodine and pilocarpine. CONCLUSIONS: A combination of tolterodine/pilocarpine (2/9) effectively reduced the incidence of dry mouth compared with tolterodine IR alone while maintaining treatment efficacy in OAB.

Pharmacokinetics of oral cyclosporin A when co-administered to enhance the oral absorption of paclitaxel.

The objective of this study was to evaluate the pharmacokinetics of oral cyclosporin A (CsA) when co-administered to enhance the oral absorption of paclitaxel. Patients received oral paclitaxel in doses of 60-360 mg/m(2) in combination with a dose of oral CsA of 15 mg/kg. Dose escalation of paclitaxel from 60 to 300 mg/m(2) resulted in a significant decrease in the area under the concentration-time curve (AUC) of CsA from 24.4+/-9.9 to 17.6+/-2.8 mg/l.h (p=0.03) (n=28). In conclusion, increases in the paclitaxel dose resulted in a decrease in the AUC of CsA. This observation may be explained by the increase in the co-solvent Cremophor EL of paclitaxel causing reduced absorption of CsA.

A phase I and pharmacokinetic study of bi-daily dosing of oral paclitaxel in combination with cyclosporin A.

PURPOSE: To investigate dose escalation of bi-daily (b.i.d.) oral paclitaxel in combination with cyclosporin A in order to improve and prolong the systemic exposure to paclitaxel and to explore the maximum tolerated dose and dose limiting toxicity (DLT) of this combination. PATIENTS AND METHODS: A total of 15 patients received during course 1 two doses of oral paclitaxel (2 x 60, 2 x 90, 2 x 120, or 2 x 160 mg/m2) 7 h apart in combination with 15 mg/kg of cyclosporin A, co-administered to enhance the absorption of paclitaxel. During subsequent courses, patients received 3-weekly intravenous paclitaxel at a dose of 175 mg/m2 as a 3-h infusion. RESULTS: Toxicities observed following b.i.d. dosing of oral paclitaxel were generally mild and included toxicities common to paclitaxel administration and mild gastrointestinal toxicities such as nausea, vomiting, and diarrhea, which occurred more often at the higher dose levels. Dose escalation of b.i.d. oral paclitaxel from 2 x 60 to 2 x 160 mg/m2 did not result in a significant increase in the area under the plasma concentration-time curve (AUC) of paclitaxel. The AUC after doses of 2 x 60, 90, 120, and 160 mg/m2 were 3.77 +/- 2.70, 4.57 +/- 2.43, 3.62 +/- 1.58, and 8.58 +/- 7.87 microM.h, respectively. The AUC achieved after intravenous administration of paclitaxel 175 mg/m2 was 17.95 +/- 3.94 microM.h. CONCLUSION: Dose increment of paclitaxel did not result in a significant additional increase in the AUC values of the drug. Dose escalation of the b.i.d. dosing regimen was therefore not continued up to DLT. As b.i.d. dosing appeared to result in higher AUC values compared with single-dose administration (data which we have published previously), we recommend b.i.d. dosing of oral paclitaxel for future studies. Although pharmacokinetic data are difficult to interpret, due to the limited number of patients at each dose level and the large interpatient variability, we recommend the dose level of 2 x 90 mg/m2 for further investigation, as this dose level showed the highest systemic exposure to paclitaxel combined with good safety.

The effect of different doses of cyclosporin A on the systemic exposure of orally administered paclitaxel.

The objective of this study was to define the minimally effective dose of cyclosporin A (CsA) that would result in a maximal increase of the systemic exposure to oral paclitaxel. Six evaluable patients participated in this randomized cross-over study in which they received at two occasions two doses of 90 mg/m(2) oral paclitaxel 7 h apart in combination with 10 or 5 mg/kg CsA. Dose reduction of CsA from 10 to 5 mg/kg resulted in a statistically significant decrease in the area under the plasma concentration-time curve (AUC) and time above the threshold concentrations of 0.1 microM (T>0.1 microM) of oral paclitaxel. The mean (+/-SD) AUC and T>0.1 microM values of oral paclitaxel with CsA 10 mg/kg were 4.29+/-0.88 microM x h and 12.0+/-2.1 h, respectively. With CsA 5 mg/kg these values were 2.75+/-0.63 microM x h and 7.0+/-2.1 h, respectively (p=0.028 for both parameters). In conclusion, dose reduction of CsA from 10 to 5 mg/kg resulted in a significant decrease in the AUC and T>0.1 microM values of oral paclitaxel. Because CsA 10 mg/kg resulted in similar paclitaxel AUC and T>0.1 microM values compared to CsA 15 mg/kg (data which we have published previously), the minimally effective dose of CsA is determined at 10 mg/kg.

Oral paclitaxel and concurrent cyclosporin A: targeting clinically relevant systemic exposure to paclitaxel.

Oral paclitaxel is not inherently bioavailable because of the overexpression of P-glycoprotein by intestinal cells and the significant first-pass extraction by cytochrome P450-dependent processes. This study sought to simulate the toxicological and pharmacological profile of a clinically relevant schedule of paclitaxel administered on clinically relevant i.v. dosing schedules in patients with advanced solid malignancies using oral paclitaxel administered with cyclosporin A, an inhibitor of both P-glycoprotein and P450 CYP3A. Nine patients were treated with a single course of oral paclitaxel in its parenteral formulation at a paclitaxel dose level of 180, 360, or 540 mg. Cyclosporin A was administered at a dose of 5 mg/kg p.o. 1 h before and concurrently with oral paclitaxel. Blood sampling was performed to evaluate the pharmacokinetics of paclitaxel, 6-alpha-hydroxypaclitaxel, 3-p-hydroxypaclitaxel, and cyclosporin A. The pharmacokinetic behavior of paclitaxel was characterized using both compartmental and noncompartmental methods. Model-estimated parameters were used to simulate paclitaxel concentrations after once daily and twice daily oral administration of paclitaxel and cyclosporin A. Aside from an unpleasant taste, the oral regimen was well tolerated, and there were no grade 3 or 4 drug-related toxicities. The systemic exposure to paclitaxel, as assessed by maximum plasma concentration (Cmax) and area under the plasma concentration versus time curve (AUC) values, did not increase as the dose of paclitaxel was increased from 180 to 540 mg, and there was substantial interindividual variability (4-6-fold) at each dose level. Mean paclitaxel Cmax values approached plasma concentrations achieved with clinically relevant parenteral dose schedules, averaging 268+/-164 ng/ml. AUC values averaged 3306+/-1977 ng x h/ ml, which was significantly lower than AUC values achieved with clinically relevant i.v. paclitaxel dose schedules. However, computer simulations using pharmacokinetic parameters derived from the present study demonstrated that pharmacodynamically relevant steady-state plasma paclitaxel concentrations of at least 0.06 microM would be achieved after protracted once daily and twice daily dosing with oral paclitaxel and cyclosporin A. Paclitaxel metabolites were detectable in three patients, and the 6-alpha-hydroxypaclitaxel: paclitaxel and 3-p-hydroxypaclitaxel:paclitaxel AUC ratios averaged 0.63 and 0.86, respectively; these values were substantially higher than values reported in patients treated with i.v. paclitaxel. Oral paclitaxel was bioavailable in humans when administered in combination with oral cyclosporin A 5 mg/kg 1 h before and concurrently with paclitaxel treatment, and plasma paclitaxel concentrations achieved with this schedule were biologically relevant and approached concentrations attained with clinically relevant parenteral dose schedules. However, treatment of patients with oral paclitaxel using a single oral dose administration schedule failed to achieve sufficiently high systemic drug exposure and pharmacodynamic effects. In contrast, computer simulations demonstrated that clinically relevant pharmacodynamic effects are likely to be achieved with multiple once daily and twice daily oral paclitaxel-cyclosporin A dosing schedules.

Phase I and pharmacokinetic study of oral paclitaxel.

PURPOSE: To investigate dose escalation of oral paclitaxel in combination with dose increment and scheduling of cyclosporine (CsA) to improve the systemic exposure to paclitaxel and to explore the maximum-tolerated dose (MTD) and dose-limiting toxicity (DLT). PATIENTS AND METHODS: A total of 53 patients received, on one occasion, oral paclitaxel in combination with CsA, coadministered to enhance the absorption of paclitaxel, and, on another occasion, intravenous paclitaxel at a dose of 175 mg/m(2) as a 3-hour infusion. RESULTS: The main toxicities observed after oral intake of paclitaxel were acute nausea and vomiting, which reached DLT at the dose level of 360 mg/m(2). Dose escalation of oral paclitaxel from 60 to 300 mg/m(2) resulted in significant but less than proportional increases in the plasma area under the concentration-time curve (AUC) of paclitaxel. The mean AUC values +/- SD after 60, 180, and 300 mg/m(2) of oral paclitaxel were 1.65 +/- 0.93, 3.33 +/- 2.39, and 3.46 +/- 1.37 micromol/L.h, respectively. Dose increment and scheduling of CsA did not result in a further increase in the AUC of paclitaxel. The AUC of intravenous paclitaxel was 15.39 +/- 3.26 micromol/L.h. CONCLUSION: The MTD of oral paclitaxel was 300 mg/m(2). However, because the pharmacokinetic data of oral paclitaxel, in particular at the highest doses applied, revealed nonlinear pharmacokinetics with only a moderate further increase of the AUC with doses up to 300 mg/m(2), the oral paclitaxel dose of 180 mg/m(2) in combination with 15 mg/kg oral CsA is considered most appropriate for further investigation. The safety of the oral combination at this dose level was good.

Metabolism and excretion of paclitaxel after oral administration in combination with cyclosporin A and after i.v. administration.

The objective of this study was to compare the quantitative excretion of paclitaxel and metabolites after i.v. and oral drug administration. Four patients received 300 mg/m2 paclitaxel orally 30 min after 15 mg/kg oral cyclosporin A, co-administered to enhance the uptake of paclitaxel. Three weeks later these and three other patients received 175 mg/m2 paclitaxel by i.v. infusion. Blood samples, urine and feces were collected up to 48-96 h after administration, and analyzed for paclitaxel and metabolites. The area under the plasma concentration-time curve of paclitaxel after i.v. administration (175 mg/m2) was 16.2 +/- 1.7 microM x h and after oral administration (300 mg/m2) 3.8 +/- 1.5 microM x h. Following i.v. infusion of paclitaxel, total fecal excretion was 56 +/- 25%, with the metabolite 6alpha-hydroxypaclitaxel being the main excretory product (37 +/- 18%). After oral administration of paclitaxel, total fecal excretion was 76 +/- 21%, of which paclitaxel accounted for 61 +/- 14%. In conclusion, after i.v. administration of paclitaxel, excretion occurs mainly in the feces with the metabolites as the major excretory products. Orally administered paclitaxel is also mainly excreted in feces but with the parent drug in highest amounts. We assume that this high amount of parent drug is due to incomplete absorption of orally administered paclitaxel from the gastrointestinal tract.

Comparative metabolism of the antiviral dimer 3'-azido-3'-deoxythymidine-P-2',3'-dideoxyinosine and the monomers zidovudine and didanosine by rat, monkey, and human hepatocytes.

AZT-P-ddI is an antiviral heterodimer composed of one molecule of 3'-azido-3'-deoxythymidine (AZT) and one molecule of 2',3'-dideoxyinosine (ddI) linked through their 5' positions by a phosphate bond. The metabolic fate of the dimer was studied with isolated rat, monkey, and human hepatocytes and was compared with that of its component monomers AZT and ddI. Upon incubation of double-labeled [14C]AZT-P-[3H]ddI in freshly isolated rat hepatocytes in suspension at a final concentration of 10 microM, the dimer was taken up intact by cells and then rapidly cleaved to AZT, AZT monophosphate, ddI, and ddI monophosphate. AZT and ddI so formed were then subject to their respective catabolisms. High-performance liquid chromatography analyses of the extracellular medium and cell extracts revealed the presence of unchanged dimer, AZT, 3'-azido-3'-deoxy-5'-beta-D-glucopyranosylthymidine (GAZT), 3'-amino-3'-deoxythymidine (AMT), ddI, and a previously unrecognized derivative of the dideoxyribose moiety of ddI, designated ddI-M. Trace extracellular but substantial intracellular levels of the glucuronide derivative of AMT (3'-amino-3'-deoxy-5'-beta-D-glucopyranosylthymidine [GAMT]) were also detected. Moreover, the extent of the formation of AMT, GAZT, and ddI-M from the dimer was markedly lower than that with AZT and ddI alone by the hepatocytes. With hepatocytes in primary culture obtained from rat, monkey, and human, large interspecies variations in the metabolism of AZT-P-ddI were observed. While GAZT and ddI-M, metabolites of AZT and ddI, respectively, as well as AZT 5'-monophosphate (MP) and ddI-MP were detected in the extracellular media of all species, AMT and GAMT were produced only by rat and monkey hepatocytes. No such metabolites were formed by human hepatocytes. The metabolic fate of the dimer by human hepatocytes was consistent with in vivo data recently obtained from human immunodeficiency virus-infected patients.

Phase I dose-escalation pharmacokinetics of AZT-P-ddI (IVX-E-59) in patients with human immunodeficiency virus.

3'-Azido-3'-deoxythymidilyl-(5',5')-2',3'-dideoxy-5'-inosinic acid (AZT-P-ddI, IVX-E-59, Scriptene) is a heterodimer composed of one molecule of 3'-azido-3'-deoxythymidine (zidovudine or AZT) and one molecule of 2',3'-dideoxyinosine (didanosine or ddI) linked through their 5' positions by a phosphate bond. AZT-P-ddI exhibits enhanced antiviral activity and selectivity in vitro compared with AZT and ddI alone. The pharmacokinetics of AZT-P-ddI were studied in 12 patients with human immunodeficiency virus (HIV) who had CD4+ cell counts higher than 200 cells/mm3. Isotopic preparations of (14C)-AZT-P-(3H)-ddI were administered intravenously (50 mg and 100 mg) to eight patients; 1 month later these patients were crossed over to oral administration (100 mg and 200 mg). A second group of patients (n = 4) received only a 450-mg oral dose of AZT-P-ddI. Plasma levels of unchanged AZT-P-ddI after intravenous infusion declined rapidly and were undetectable 0.75 hours after the end of infusion, whereas the parent compound was not detected after oral administration, indicative of a very rapid metabolism. The parent entity was enzymatically cleaved in vivo yielding the two constituent drugs AZT and ddI, which were subsequently subjected to their respective pharmacokinetic and metabolic processes. The beta-glucuronide derivative of AZT (GAZT) represented the major metabolite of AZT, but there were no detectable levels of the toxic metabolite 3'-amino-3'-deoxythymidine (AMT). A major and previously unrecognized in vivo metabolite of ddI, referred as ddI-M, was detected in plasma and urine. Analysis by high-field proton nuclear magnetic resonance and mass spectrometry led to the identification of ddI-M as being R(-)-dihydro-5-(hydroxymethyl)-2(3H)-furanone. The formation of AZT and ddI metabolites was increased after oral administration of AZT-P-ddI compared with the intravenous infusion, with an area under the concentration-time curve (AUC) ratio of metabolite to AZT and metabolite to ddI being 7.7 and 5.7 (oral) and 3.8 and 1.1 (intravenous), respectively. The newly identified ddI-M exhibited sustained plasma levels for extended time periods with an apparent elimination half-life (t1/2) of approximately 10 hours after oral administration of AZT-P-ddI. Recovery of radioactivity associated with 3H and 14C in urine was essentially complete within 48 hours after oral and intravenous administration of AZT-P-ddI. The oral bioavailability of AZT (64.7-67.3%) and ddI (33.6-42.9%) and the other pharmacokinetic parameters were consistent with previous data reported with each nucleoside analog alone or in combination therapy.

Phase I trial of orally administered pentosan polysulfate in patients with advanced cancer.

Tumor angiogenesis is critically important to tumor growth and metastasis. We have shown that pentosan polysulfate (PPS) is an effective inhibitor of heparin-binding growth factors in vitro and can effectively inhibit the establishment and growth of tumors in nude mice. Following completion of our Phase I trial of s.c. administered PPS, we performed a Phase I trial of p.o. administered PPS in patients with advanced cancer to determine the maximum tolerated dose (MTD) and toxicity profile and to search for any evidence for biological activity in vivo. Patients diagnosed with advanced, incurable malignancies who met standard Phase I criteria and who did not have a history of bleeding complications were enrolled, in cohorts of three, to receive PPS p.o. t.i.d., at planned doses of 180, 270, 400, 600, and 800 mg/m2. Patients were monitored at least every 2 weeks with physical exams and weekly with hematological, chemistry, stool hemoccult, and coagulation blood studies, and serum and urine samples for PPS and basic fibroblastic growth factor (bFGF) levels were also taken. The PPS dose was escalated in an attempt to reach the MTD. Eight additional patients were enrolled at the highest dose to further characterize the toxicity profile and biological in vivo effects of PPS. A total of 21 patients were enrolled in the three cohorts of doses 180 (n = 4), 270 (n = 3), and 400 (n = 14) mg/m2. The most severe toxicities seen were grade 3 proctitis and grade 4 diarrhea; however, 20 of the 21 patients had evidence of grade 1 or 2 gastrointestinal (GI) bleeding. These toxicities became evident at a much earlier time point as the dose was increased, but their severities were similar at all dose levels. There were no objective responses, although three patients had prolonged stabilization of previously progressing disease. Pharmacokinetic analysis suggested marked accumulation of PPS upon chronic administration. Serum and urine bFGF levels failed to show a consistent, interpretable pattern; however the data suggested an inverse relationship between PPS and bFGF levels in vivo. A MTD could not be determined using the daily t.i.d. dosing schedule due to the development of grade 3/4 GI toxicity (proctitis) at all dose levels studied. PPS, administered p.o. at doses of 400 mg/m2 t.i.d., did not cause significant systemic toxicity, but most patients developed moderate-to-severe GI toxicity within 1-2 months. The cause of the GI toxicity was unclear, but it was readily reversible upon cessation of the agent. The suggestion of an inverse relationship between PPS and bFGF supports further study of PPS as an antiangiogenic agent. The tested doses and schedule cannot be recommended for further study. Subsequent murine experiments showed PPS to be more effective as an anticancer agent when it is given intermittently. We propose a study of PPS given on a weekly schedule in further clinical trials.

Bioequivalence of a highly variable drug: an experience with nadolol.

PURPOSE: To assess the bioequivalence of nadolol 40mg and 160mg tablets (Zenith-Goldline Pharmaceuticals) using Corgard 40mg and 160mg tablets (Bristol-Meyers Squibb) as reference products, to estimate the effect of food in the gastrointestinal tract on nadolol bioavailability, and to evaluate the effectiveness of standard pharmacokinetic metrics AUCt, AUC infinity, and Cmax in bioequivalence determinations. METHODS: Four bioequivalence studies were conducted as described in the FDA Guidance. Four additional studies of varying designs were conducted to establish bioequivalence of the 40mg tablet in terms of Cmax. RESULTS: Fasted and food-effect studies of the 160mg tablet clearly established bioequivalence and revealed an unexpected reduction in nadolol bioavailability from test and reference products in the presence of food. The food-effect study of the 40mg tablet (80mg dose) revealed a similar reduction in bioavailability from each product. Fasted studies of the 40mg tablet (80mg dose) established bioequivalence in terms of AUCt and AUC infinity. However, Cmax criteria proved extremely difficult to meet in the initial 40mg fasted study because of the large variability, leading to additional studies and ultimately requiring an unreasonable number of subjects. CONCLUSIONS: Final results clearly established bioequivalence of both strengths and characterized an unexpected food effect which did not appear to be formulation-related. However, the Cmax of nadolol is only slightly sensitive to absorption rate and the relatively large variability of Cmax reduces its effectiveness as a bioequivalence metric. Findings suggest that bioequivalence criteria for highly variable drugs should be reconsidered.

Anti-hypertensive effects of intravenous compared with oral captopril.

Twenty mild to moderate hypertensive subjects (11 men, 9 women, mean age 54.3 years, range 39-65 years) were studied to determine whether an intravenous form of captopril could be as safe and efficacious as an oral form and to estimate the time course of anti-hypertensive action over a wide dose range (100-fold) of i.v. doses versus oral captopril and placebo. Each subject demonstrated supine diastolic blood pressure (DBP) < or = 90 mm Hg following prospective ACE inhibitor monotherapy, with return of supine DBP to within 95-110 mm Hg 4 weeks after ACE inhibitor discontinuation. These subjects were then admitted to an inpatient unit for six 24 h periods; an initial acclimation period followed by five single doses of i.v. captopril (1.25, 12.5 and 125 mg) or placebo given as a 20 min infusion and oral captopril (25 mg) or placebo in a double-blind, double-dummy crossover study. Each dose was separated by 48 h. All 20 patients completed the study with no clinically significant adverse events. Captopril at doses of 125 mg i.v., 12.5 mg i.v. and 25 mg orally produced similar BP reductions over the 12 h postdose interval, and were more effective in lowering BP than intravenous captopril 1.25 mg or placebo. The 125 mg intravenous captopril dose was no more effective overall in BP reduction than the 12.5 mg i.v. and 25 mg oral doses and was associated with a greater incidence of adverse events. Treatment with 12.5 mg i.v. captopril is safe and comparable to 25 mg oral therapy.

The pharmacokinetics and pharmacodynamics of fosinopril in haemodialysis patients.

The pharmacokinetics and pharmacodynamics of fosinoprilat, the diacid of fosinopril sodium (a new angiotensin-converting enzyme (ACE) inhibitor), were investigated in six haemodialysis patients. Intravenous 14C-fosinoprilat (7.5 mg), oral 14C-fosinopril sodium (10 mg) and oral fosinopril sodium (10 mg) were administered in an open-label, randomized study. Mean maximum concentration (Cmax), clearance (CL), volume of distribution at steady-state (Vss), mean residence time (MRTiv), and t1/2 values after IV administration of 14C-fosinoprilat were 2,042 micrograms.ml-1, 11.3 ml.min-1, 11.0 l, 16.3 h and 28.3 h, respectively. Following oral administration of 14C-fosinopril, mean Cmax, time to maximum plasma concentration (tmax), and fosinoprilat bioavailability values were 197 ng.ml-1, 5.2 h and 29.2%. Para-hydroxy fosinoprilat and fosinoprilat glucuronide comprised approximately 15% and 2% of radioactivity recovered in faeces. Four hours of haemodialysis only cleared approximately 1.5% of the administered dose. The maximum effect (Emax) model was fitted to the percentage inhibition of serum ACE activity vs. fosinoprilat concentration data in three patients. Emax ranged from 95.3 to 102.5%, and IC50 (the fosinoprilat concentration required to produce 50% of Emax) ranged from 2.6 to 4.2 ng.ml-1. Pharmacokinetic variables of the patients were similar to those in patients with moderate to severe renal dysfunction. Dosage modifications or supplemental dosing following dialysis are unnecessary.

Once-daily fosinopril in the treatment of hypertension.

This multicenter, dose-ranging study evaluated the antihypertensive effectiveness of once-daily administration of fosinopril sodium in 220 patients with supine diastolic blood pressure of 95-115 mm Hg. After a 4-week placebo period, patients were randomly assigned to double-blind therapy with either placebo or 10, 40, or 80 mg fosinopril once daily for 4 weeks. If treatment goals were not met, chlorthalidone 25 mg/day was added for weeks 5 to 8. Thereafter, patients could enter the long-term, open-label phase and receive 10-80 mg/day fosinopril plus chlorthalidone, if needed. After 4 weeks of monotherapy, the average decreases in supine diastolic blood pressure were 9% (10 mg), 11.5% (40 mg), and 12.5% (80 mg) compared with 6% in the placebo group. After 8 weeks, the average decreases, with or without diuretic therapy, were 12.5-18.2%, compared with 10.8% with placebo. Blood pressure continued to be well controlled, and the patients showed no evidence of tachyphylaxis or tolerance through 12-15 months of treatment. Fosinopril was well tolerated. During the short-term phase, no patient withdrew because of adverse events possibly related to fosinopril; during the long-term phase, nine of 148 patients (6.1%) withdrew for that reason. In patients with mild-to-moderate hypertension, once-daily fosinopril (40 and 80 mg) provided significant antihypertensive effects with or without diuretic therapy. The 10 mg dose was effective in some patients and may be considered a starting dose.

Pharmacokinetics of fosinopril in patients with various degrees of renal function.

Single-dose kinetics of fosinopril, a new phosphorus-containing angiotensin-converting enzyme inhibitor and its active diacid, fosinoprilat, were investigated in patients with mild, moderate, or severe renal impairment and in those with normal renal function. After an intravenous dose of 14C-fosinoprilat (7.5 mg), total body clearance of fosinoprilat was significantly greater (p less than 0.05) in patients with normal renal function than in renally impaired patients but was not related to the degree of renal impairment in patients with creatinine clearance values of 11 to 72 ml/min/1.73 m2. Decreases in renal clearance were compensated for by increases in hepatic clearance, so that total clearance was maintained. After oral 14C-fosinopril (10 mg), plasma kinetics and bioavailability of fosinoprilat were similar for the three groups of renally impaired patients. The dual elimination of fosinoprilat by the liver and the kidney distinguishes fosinopril from other angiotensin-converting enzyme inhibitors.

Fosinopril pharmacokinetics and pharmacodynamics in chronic ambulatory peritoneal dialysis patients.

The pharmacokinetics and pharmacodynamics of fosinoprilat, the diacid of fosinopril sodium, a new angiotensin-converting enzyme (ACE) inhibitor, were investigated after the oral administration of 10 mg of fosinopril sodium to 6 chronic ambulatory peritoneal dialysis (CAPD) patients. The results from 1 patient are reported separately because of the presence of concomitant liver dysfunction. The mean t1/2, Cmax, tmax, and AUC values for 5 of the CAPD patients were 19.5 h, 202 ng.ml-1, 4.8 h, and 3.19 micrograms.h.ml-1, respectively. Values for 1 CAPD patient with liver dysfunction were t1/2 of 65.4 h, Cmax of 182 ng.ml-1, tmax of 9 h, and AUC of 18.1 micrograms.h.ml-1. Peritoneal clearance of fosinoprilat was negligible, ranging from 0.07 to 0.23 ml.min-1. Serum ACE activity remained significantly suppressed at 24 and 48 h after fosinopril sodium administration with mean decreases from baseline of 94.2% and 70.6%, respectively. ACE activity was suppressed to an even greater degree in the patient with liver dysfunction, remaining 97% inhibited 72 h after drug administration. Plasma renin activity (PRA) increased and plasma aldosterone concentrations decreased following drug administration. Mean arterial pressure did not change appreciably throughout the study. Dosage reductions may not be necessary in the majority of dialysis patients.

Pharmacokinetics, safety, and pharmacologic effects of fosinopril sodium, an angiotensin-converting enzyme inhibitor in healthy subjects.

The pharmacokinetics, pharmacodynamics, and safety of fosinopril sodium (SQ 28,555), a new orally active angiotensin-converting enzyme (ACE) inhibitor, was evaluated in 73 healthy men in two separate studies. In study I, doses ranging from 10 to 640 mg were administered once daily for 3 days to seven groups of five subjects each. Serum aldosterone levels, ACE activity, and sitting blood pressure were determined, as were pharmacokinetic parameters of fosinoprilat, the active diacid of fosinopril. In a dose-tolerance study (study II), 80 and 160 mg of the drug were administered in doses of 40 mg bid and 80 mg bid for 2 weeks. Pharmacokinetics were determined on days 1 and 14, and blood pressure and ACE activity were measured daily. One hour after all doses of fosinopril, serum ACE activity was undetectable. Peak blood levels of fosinoprilat occurred at about 3 hours after dosing, and linear kinetics of the diacid were observed. ACE activity remained undetectable for more than 24 hours after the treatment was stopped in study II. Serum aldosterone levels were decreased by 50% of baseline values in both studies. In study I, maximal reductions in mean blood pressure occurred approximately 6 hours postdose; once-daily doses of 20 mg or greater achieved reductions of 11.3 to 21.6% (P less than or equal to .05, compared with placebo reductions). Fosinopril was well tolerated. Subjects reported only mild gastrointestinal complications at doses of 80 mg/day or higher. These data show that fosinopril is a safe and effective inhibitor of ACE with a long duration of action on serum ACE activity.

Pharmacokinetics of captopril in healthy subjects and in patients with cardiovascular diseases.

Captopril, the first orally active inhibitor of angiotensin-converting enzyme, is used widely in the treatment of hypertension and congestive heart failure. The pharmacokinetics of this agent have been studied extensively in healthy subjects and in patients with hypertension, congestive heart failure, and chronic renal failure. Captopril contains a sulphydryl group and binds readily to albumin and other plasma proteins. The drug also forms mixed disulphides with endogenous thiol-containing compounds (cysteine, glutathione), as well as the disulphide dimer of the parent compound. These components in blood and urine are measured collectively as total captopril. Because of the reversibility of the formation of these inactive disulphides, total captopril may serve as a reservoir of the pharmacologically active moiety, and thus contribute to a duration of action longer than that predicted by blood concentrations of unchanged captopril. To measure free or unchanged captopril concentrations, a chemical stabiliser must be added to the biological samples to prevent the formation of captopril disulphides ex vivo. In healthy subjects given captopril intravenously, the body clearance of captopril and steady-state volume of distribution were about 0.7 L/h/kg and 0.8 L/kg, respectively. The elimination half-life of unchanged captopril was approximately 2 hours. The primary route of elimination of captopril is the kidney. The renal clearance of unchanged captopril exceeds the glomerular filtration rate, due to active tubular secretion of the drug. In healthy subjects, about 70 to 75% of an oral dose is absorbed and the bioavailability of captopril is approximately 65%. Peak blood concentrations are reached about 45 to 60 minutes after oral administration. The bioavailability of captopril is not altered by age or concomitant medications including diuretics, procainamide, allopurinol, cimetidine or digoxin. However, the co-administration of food or antacids, or probenecid with captopril has been shown to diminish the bioavailability of the latter and decrease its clearance, respectively. The decreased bioavailability of captopril when taken with meals does not significantly alter clinical responses to the drug. Over a wide range of oral (10 to 150 mg) and intravenous doses (2.5 to 10 mg) captopril had linear kinetics in healthy volunteers. In healthy subjects with normal renal function and patients with congestive heart failure given captopril 3 times daily, blood concentrations of total captopril accumulated, whereas those of unchanged captopril did not. Severe renal insufficiency was associated with an accumulation of both unchanged and total captopril.(ABSTRACT TRUNCATED AT 400 WORDS)

Disposition of fosinopril sodium in healthy subjects.

1 Fosinopril sodium is the first phosphorus-containing angiotensin-converting enzyme (ACE) inhibitor to be studied clinically as an antihypertensive agent. It is an ester prodrug that is hydrolysed in vivo to the active diacid ACE inhibitor, SQ 27, 519. 2 In a three-way crossover study, nine healthy male subjects (age range 20-34 years) each received an intravenous 7.5 mg dose of SQ 27, 519-[14C] and two oral 10 mg doses of [14C]-fosinopril sodium, administered as a capsule and in solution. 3 After the intravenous dose of SQ 27, 519, the 0 to 96 h recovery of radioactivity averaged 44 and 46% of the dose in urine and faeces, respectively, indicating substantial biliary secretion. Only intact SQ 27, 519 was detected in the plasma, urine, and faeces following the intravenous dose of SQ 27, 519. 4 After oral doses of fosinopril sodium, about 75% of the radioactivity in plasma and urine was present as SQ 27, 519; the remainder corresponded mainly to a beta-glucuronide conjugate of SQ 27, 519 (15-20%), and a monohydroxylated analogue of SQ 27, 519 (about 5%). Negligible amounts of fosinopril sodium were present, indicating complete hydrolysis of the prodrug. 5 For the solution and capsule doses, respectively, the oral absorption of fosinopril sodium averaged 32% and 36% and the oral bioavailability of SQ 27, 519 averaged 25% and 29%. 6 The average values for clearance (39 ml min-1), renal clearance (17 ml min-1), Vss (10 1), and plasma protein binding (approximately 95%), indicated that SQ 27, 519 was slowly cleared from the body and not distributed extensively into extravascular sites.