The relative bioavailability of a commercial propranolol hydrochloride tablet in man

A relative bioavailability study of a conventional tablet of propranolol hydrochloride was conducted in a group of 18 healthy volunteers employing the innovator's product as the reference tablet formulation. Based on plasma levels of propranolol for the 24 h following administration of 2 ± 40 mg oral propranolol hydrochloride tablets, the relative extent of bioavailability was shown to be 100.8 per cent for the test tablet formulation; no significant differences were detected between formulations with respect to any of the pharmacokinetic parameters examined. Large intersubject variations in plasma propranolol concentrations and the subsequently calculated areas under the plasma concentration/time curves were attributed to substantial presystemic biotransformation differences.     

The effects of food and posture on the pharmacokinetics of a biphasic release preparation of nifedipine.

The pharmacokinetics of a novel 20 mg biphasic release tablet of nifedipine were compared with the conventional 10 mg capsule and 20 mg sustained release preparations in healthy volunteers. The influence of food and posture on the pharmacokinetics of the biphasic tablet were studied. In the fasting state, the time to peak concentration of nifedipine was not significantly different between the 20 mg biphasic and 20 mg sustained release tablets, but plasma concentrations were higher between 2 and 4 h after the biphasic tablet. The terminal elimination half-lives of the two formulations were similar. In subjects who fed prior to nifedipine administration there was no significant difference between either the peak plasma concentration or terminal half-life of the biphasic tablet and two 10 mg capsules of nifedipine. When the biphasic preparation was given after a standard breakfast, the time to peak plasma concentration was significantly longer and the terminal half-life shorter than when given in the fasting state. The dissolution characteristics of the biphasic tablet were influenced by prior administration of food to an extent which may be of clinical significance during twice daily administration.     

普萘洛尔药物树脂渗透泵在犬体内的药动学及体内外相关性评价

目的对制备的普萘洛尔药物树脂渗透泵片在Beagle犬体内药动学进行研究并对体内外相关性做出评价。方法对6条Beagle犬进行双周期双交叉实验,利用高效液相色谱法测定不同时间Beagle犬血浆中的药物浓度,用DAS 2.0统计软件计算有关药动学参数。以紫外分光光度计测定普萘洛尔树脂渗透泵控释片的体外释放浓度,Wanger-Nelson法计算体内吸收百分数,进行体内外相关性评价。结果药物树脂渗透泵体外释放具有2 h时滞,2～14 h恒速释药,24 h累积释放90%以上。体内吸收5 h后达到最低有效浓度,普萘洛尔树脂渗透泵片与普通片主要药动学参数分别为t_(max)(11.0±s 1.1)和(3.0±0.6)h;t_(1/2) (6±4)和(3.2±0.6)h;c_(max)(128±11)和(750±55)μg·L~(-1);AUC_(0-∞)(2583±508)和(2 708±386)μg·h·L~(-1),且体内外相关性较好。结论普萘洛尔树脂渗透泵片的时滞现象为时辰给药提供了可能,且血药浓度平稳,与普通片相比可较长时间保持有效血药浓度。     

A combined single and multiple dose pharmacokinetic study of oral isosorbide-5-mononitrate in healthy volunteers.

Pharmacokinetics of 20 mg isosorbide-5-mononitrate (IS-5-MN) after single and multiple administration of two different tablet formulations were investigated in twelve healthy human subjects using an open, randomized, two-way crossover experimental design. Pentacard 20 mg tablets were compared with Ismo 20 mg tablets. After single-dose administration, both preparations caused a rapid increase in IS-5-MN plasma levels with the peak plasma concentration occurring between 0.5 and 1.5 h. For both formulations, the mean plasma half-life was found to be approximately 5 h after a single dose. In steady state during multiple dosing (t.i.d. at 8 h dosing intervals), a reduced elimination rate was observed. In line with this observation, the area under the plasma concentration-time curve (AUC) for one 8 h dosing interval during multiple dosing was higher than the extrapolated AUC after a single dose. Based on statistical evaluation of the various relevant pharmacokinetic parameters calculated from the plasma concentrations occurring after single and multiple dosing, the tablet formulations are judged to be bioequivalent.     

Single dose pharmacokinetics of fenspiride hydrochloride: phase I clinical trial

Summary The absolute bioavailability of fenspiride has been studied in twelve healthy volunteers. It was administered IV and orally in single doses of 80 mg fenspiride hydrochloride according to a randomised crossover pattern.Following IV administration, the plasma clearance of fenspiride was about 184 ml·min^–1, and its apparent volume of distribution was moderately large (2151).When given orally as a tablet, fenspiride exhibited fairly slow ab- sorption; the maximum plasma concentration (206 ng·ml^–1) was achieved 6 h after administration. The absolute bioavailability was almost complete (90%). The tablet had slow release characteristics. The elimination half-life obtained from the plasma data was 14 to 16 h independent of the route of administration.     

Comparative pharmacodynamics and pharmacokinetics of conventional and long-acting propranolol

This investigation was conducted to compare the pharmacokinetic and pharmacodynamic effects of single and multiple doses of conventional propranolol and long-acting propranolol in healthy human volunteers. Two double-blind, randomized, double-crossover, Latin square studies were carried out. One study evaluated long-acting propranolol 160 mg/d, conventional propranolol 40 mg qid, or placebo for seven days in 24 men. The other study compared long-acting propranolol 80 mg/d, conventional propranolol 20 mg qid, or placebo for seven days in 27 men. At specific times after the administration, blood samples were obtained, and heart rate and blood pressure were measured; exercise tests were done both on the first day and at steady state (day 7). In both studies, the area under the plasma propranolol concentration-time curve and the peak concentration were significantly less (P less than .0001) after the administration of long-acting propranolol compared with conventional propranolol on both day 1 and day 7; in addition, the elimination half-life was longer after administration of the long-acting preparation (9 hr) compared with that following the conventional dosage form (4 hr). Both conventional and long-acting propranolol significantly decreased the exercise heart rate at each of the selected time points (P less than .05) compared with placebo. Reduction in exercise heart rate was greater with conventional propranolol than with the long-acting formulation, but the differences were not statistically significant, when exercise was performed only at trough levels of the conventional drug. The decreases in exercise heart rate were correlated with plasma propranolol concentrations.     

Blood levels following multiple oral dosing of chlorpheniramine conventional and controlled release preparations

An examination of steady-state performance of chlorpheniramine conventional versus controlled release products was conducted using 15 male subjects in a 3-way crossover study with a 2-week washout period between studies. The study was designed to determine if chlorpheniramine formulations provide consistent pharmacokinetic performance between individual units upon going from single dose to multiple dose therapy. In addition, the validity of predicting steady-state levels for these kinds of products using only single oral dose data was examined. The dosage forms evaluated were a conventional 4mg tablet, and 8 mg barrier coated-bead capsule, and an 8 mg repeat action tablet. Multiple doses of each product were orally administered to each subject for 6 days prior to the study day to achieve steady-state levels and on the actual study day. Serum samples were collected at specific time intervals on the study day, and chlorpheniramine levels assayed by HPLC. Pharmacokinetic analysis was based on a two-compartment open model. The mean plasma elimination half-lives of the various dosage forms were in the range 24.5–25.4h. There was no rapid release of drug from the controlled release products nor did they have drug release problems during the dosing interval. Good agreement was obtained between predicted average drug concentration at steady-state and drug concentration actually present for all the formulations studied. Based upon comparative examination of AUC, C_max, and fraction of dose absorbed data, the controlled release products administered every 12h were comparable in performance to a conventional release tablet administered every 6 h. Since the half-life of chlorpheniramine is approximately 1 day, therapeutic management may possibly be gained with dosing the patient once daily with a controlled release product or twice daily with a conventional tablet.     

A pharmacokinetic and dynamic study of single nightly doses of conventional and controlled release formulations of trazodone

We studied the pharmacokinetics and dynamics of single evening oral doses of conventional capsules (100 mg) and a controlled release formulation (150 mg) of trazodone in 12 fasting and non-fasting young healthy volunteers. When corrected for the different doses used, there was no significant difference among the areas under the plasma concentration-time curves (AUC) for the conventional capsules and the controlled release tablets under fasting and non-fasting conditions. Both conventional and controlled release formulations were followed by a reduction in critical flicker fusion threshold (CFFT) and this effect was not influenced by the administration of food before dosing. After both conventional and controlled release formulations, blood pressure was significantly lower when medication had been given in the fasting state than when it had been given after food. The frequency of adverse symptoms was greater after the controlled release (150 mg) than after the conventional (100 mg) formulation. We conclude that there is no obvious advantage to the controlled release formulation (150 mg) and that conventional trazodone (100 mg) should be taken after food when it is given at night.     

Bioavailability of morphine after administration of a new bioadhesive buccal tablet

A new bioadhesive buccal morphine tablet was developed for controlled release delivery of drug and improved bioavailability compared with oral controlled release tablet. In order to characterize the pharmacokinetic properties of this bioadhesive buccal formulation, a bioavailability study was performed in 12 healthy volunteers who received: a 30 mg oral controlled release tablet (A); a 20 mg aqueous solution retained in the mouth for 10 min (B); and the 60 mg bioadhesive buccal tablet placed between the lower gum and lip for 6 h (C). The mean amount of morphine absorbed from the solution was very low, only 2 mg of the 20 mg dose. After administration of forms A and C, plasma levels exhibit typical sustained release concentration–time curves. The mean amount of drug recovered from the residual bioadhesive buccal tablet after 6 h indicated that approximately 50% of the dose was released from the bioadhesive buccal tablet. The relative bioavailability of the buccal tablet (corrected for residual unabsorbed dose) compared with the controlled-release tablet was 98% based on the morphine AUC values. Good correlations between the AUC and the C_max of the bioadhesive tablet for the drug and metabolite plotted versus the amount of morphine absorbed were found. © 1998 John Wiley & Sons, Ltd.     

Long-Acting Propranolol (Inderal LA): Pharmacokinetics,Pharmacodynamics and Therapeutic Use

Long-acting propranolol (Inderal LA) is a new formulation of propranolol that allows release of the drug in a controlled manner, so that the plasma concentration at 24 hr after dosing is greater with long-acting propranolol than with conventional tablets. A single dose of 160 mg of long-acting propranolol can produce cardiac beta-adrenoceptor blockade throughout a 24 hr period without variability due to multiple peak concentrations. It has been shown that this formulation is as effective in the treatment of angina pectoris, hypertension and hyperthyroidism as the standard formulation. Studies with long-acting propranolol in cardiac dysrhythmias are lacking. This new dosage form would be a means of simplifying dosing regimens and thereby hopefully enhancing patient convenience and compliance.     

A pharmacodynamic and pharmacokinetic comparison of pindolol 20 mg retard and a conventional tablet

Summary In 10 healthy volunteers the time course of cardiac beta-adrenoceptor blocking activity, plasma levels and cumulative urinary excretion of pindolol were compared during a 4-day course of pindolol 5 mg (Visken^®) t. d. s., and one tablet of pindolol 20 mg retard (Visken^® retard) once a day. After oral administration of the 20 mg retard tablet, plasma concentrations of pindolol higher than half the maximum value (1/2 Cp (t_max)) were maintained about 2.5 times as long as after administration of the conventional 5 mg tablet. This is evidence for an important and marked retardation of drug release. During treatment with pindolol 20 mg retard once daily, cardiac beta-adrenoceptor blockade, measured by the reduction in exercise-induced tachycardia and in the exercise-induced rise in systolic blood pressure, at almost all times throughout the 24 h period was at least as great as during treatment with pindolol 5 mg t. d. s. This suggests that patients successfully treated with pindolol 5 mg t. d. s. can be maintained with the same beta-adrenoceptor blockade by a single tablet of pindolol 20 mg retard once daily.     

A multiple-dose pharmacokinetic comparison of naproxen as a once-daily controlled-release tablet and a twice-daily conventional tablet

The bioequivalence and absorption kinetics of naproxen in a new controlled-release tablet (750 mg or 1,000 mg naproxen) administered once daily were determined relative to an equivalent dose of the conventional naproxen tablet (375 mg or 500 mg naproxen) administered q12h. Naproxen was well absorbed from the controlled-release tablet (about 90%) compared with the conventional tablet. Absorption was dependent on drug release from the tablet matrix. The mean absorption time of naproxen averaged 8.4 hours for the 750-mg controlled-release tablet and 9.2 hours for the 1,000-mg controlled-release tablet. Once-daily administration of the controlled-release tablet resulted in equivalent trough concentrations of naproxen, and steady-state plasma concentrations were maintained within narrower limits than with twice-daily naproxen.     

Comparison of the activity and plasma levels of oxprenolol,slow release oxprenolol,long acting propranolol and sotalol

Summary Observations were made in 5 healthy subjects who exercised before and 1, 3, 6, 8 and 24 h after the oral administration on separate occasions of 160 mg oxprenolol, 160 mg slow release oxprenolol, 160 mg long acting propranolol and 400 mg sotalol. Blood samples were obtained before and at 1, 2, 3, 6, 8, 10 and 24 h after drug administration and assayed for drug concentration. Although the plasma concentration of oxprenolol after S. R. oxprenolol was significantly less at 1 and 2 h and significantly greater at 24 h than after conventional oxprenolol, there was little difference between the effects of the two drugs on an exercise tachycardia. The plasma level of propranolol and the reduction in an exercise tachycardia after L. A. propranolol increased slowly to reach a peak at 6 h and then declined gradually to 24 h. The maximum plasma concentration and effect after sotalol occurred at 3 h and then declined with an elimination half-life of 12.1 h. At 24 h the percentage reduction in an exercise tachycardia was 8.3±2.5 after oxprenolol, 10.0±2.3 after S. R. oxprenolol, 18.0±3.2 after L. A. propranolol and 14.7±3.4% after sotalol.     

Multiple-dose pharmacokinetics of naproxen from a controlled-release tablet in healthy volunteers

The pharmacokinetics of a new controlled-release tablet of naproxen (750 mg) given once daily has been studied in healthy volunteers, in comparison with two doses of the conventional naproxen tablets (375 and 500 mg) administered twice daily. Steady-state plasma concentrations of naproxen were achieved after two days of repeated administration of both the controlled-release and the conventional tablets. On day seven, peak concentration, cowest concentration and the steady-state average plasma concentration values of the controlled-release tablet were significantly higher than those of 375 mg conventional tablet and comparable to those of 500 mg conventional tablet. Areas under the plasma concentration-time curve indicated an equal extent of absorption between the new and the conventional formulation. Overall the controlled-release tablet administered once daily mimicked a twice daily regimen so suggesting that the new formulation could be suitable for once daily dosing.     

Comparative steady state bioavailability of conventional and controlled-release formulations of albuterol

A new controlled-release (CR) dosage formulation of albuterol has been developed which is suitable for twice-a-day dosing. The present study was conducted in twelve healthy adult male volunteers to compare the steady state plasma levels obtained following repeated administration of a 4 mg CR tablet (q12h) compared to a 2 mg conventional table (q6h) for 5 consecutive days. The mean steady state plasma level-time curves for both the CR and conventional tablet treatments were comparable over time and reproducible. There were no significant differences in the AUC or Cmax values between the two treatments. The mean 48-h AUC values were 240.7 and 231.3 h X ng ml-1 for the conventional and CR tablets, respectively, while the corresponding Cmax values ranged from 5.3 to 6.8 ng ml-1 and 5.4 to 6.5 ng ml-1. There were no significant differences in Cmin values except for one 12-h (day 4) value. Cmin values ranged from 3.8 to 4.3 ng ml-1 and 3.0 to 4.8 ng ml-1 for the conventional and CR tablets, respectively. The data show that the 4 mg albuterol CR tablet (q12h) is bioequivalent to a 2 mg conventional albuterol tablet (q6h). The CR tablet formulation will offer the advantage of increased patient compliance; additionally, the CR formulation may prove to be especially beneficial in the treatment of nocturnal asthma.     

A comparison of some physiological and psychological effects of Motival (fluphenazine and nortriptyline) and diazepam in normal subjects

1 The effects in normal subjects of a single oral dose of Motival (one tablet, containing fluphenazine 0.5 mg and nortriptyline 10 mg) on the contingent negative variation (CNV), reaction time, heart rate, blood pressure and self-rating scales for alertness, anxiety, tension, detachment and depression were compared with those of diazepam (5 mg and 7.5 mg) and placebo or propranolol (60 mg). 2 After diazepam (5 mg: twelve subjects and 7.5 mg: seven subjects) there was a significant decrease in CNV magnitude while after Motival (twelve subjects) there was no significant alteration in CNV magnitude compared to placebo. 3 After diazepam (7.5 mg: seven subjects) there was also a fall in subjective ratings for alertness and tension; this fall was significantly greater than the changes after Motival which did not reduce subjective ratings for alterness or tension below "average" levels. Anxiety ratings did not differ significantly between the two drugs. Changes after propranolol were intermediate in all scales. 4 It is concluded that under these conditions diazepam caused central nervous system depression while Motival did not.     

磷酸丙吡胺缓释包衣片及其生物利用度研究

研制了一种缓释的磷酸丙吡胺包衣片剂。包衣材料主要是乙基纤维素。用转篮法测定包衣片中药物的溶出速度表明,第1h 溶出约17%,可连续释药8h 以上。8名健康志愿者口服缓释包衣片200mg 后,测定了血药浓度及动力学参数,并与两种临床有效的控释磷酸丙吡胺片和胶囊剂作对照。结果表明,从起效速度,体内作用持续时间及生物利用度诸方面考察,皆可与两种或一种控释制剂相比拟。     

Bioavailability of sustained release propranolol formulations

In this comparative bioavailability study two sustained release capsule formulations of propranolol, one a clinical trial formulation and the other the U.K. sales formulation (‘Inderal’ LA), were compared with a conventional ‘Inderal’ tablet. Twelve healthy adult male volunteers received, on a cross-over basis, on three separate occasions, 160 mg oral doses of three formulations of ‘Inderal’. Bioavailability was based on concentration of propranolol in whole blood. The peak blood level and area under the propranolol blood level curve fell as the dissolution time increased. The half-lives of the three formulations were inversely proportional to their dissolution rates, those of the sustained release formulations being considerably longer than that of the conventional tablet. The 160 mg ‘Inderal’ tablet produced a rapid 90-fold decline over 24 h in propranolol blood levels following a high initial peak. By comparison both sustained release formulations showed a less rapid fall in systemic levels and gave higher blood levels at the end of 24 h and plateau values between 8 and 14 ng ml ^?1. The ‘Inderal’ LA sustained release formulation gave consistently higher propranolol blood levels than the clinical trial sustained release formulation. This result is in good agreement with their dissolution profiles. The lowering of the systemic bioavailability as the dissolution time increases is thought to be due to an increased metabolism of propranolol.     

The effect on plasma prolactin,growth hormone and luteinising hormone concentrations of single oral doses of propranolol and tolamolol in normal man

Summary In a placebo controlled double-blind study in six healthy male volunteers the effects of single oral doses of 100 mg and 200 mg of tolamolol on plasma concentrations of prolactin, growth hormone and luteinising hormone were investigated. In a second placebo controlled single-blind study in a further six healthy male volunteers the effects of single oral doses of 200 mg tolamolol and 160 mg propranolol on the same plasma hormone concentrations were compared. A dose dependent increase in plasma prolactin concentration was demonstrated after tolamolol. The increase in plasma prolactin concentration was not evident after propranolol. Plasma growth hormone and luteinising hormone concentrations were not significantly changed by either propranolol or tolamolol.Report prepared by Pfizer Central Research, Europe     

Clinical bioavailability evaluation of a controlled release formulation of diazepam

A controlled release formulation of diazepam was compared to equal daily doses of the trade tablet under single day and steadystate conditions. Virtually no differences were found in the mean steadystate concentrations of diazepam or its metabolite, N-desmethyldiazepam, when the subjects received the 5 mg trade tablet three times daily or the 15 mg controlled release formulation once daily. Similarly, there was no difference in mean diazepam or N-desmethyldiazepam plasma concentrations when single doses of the controlled release formulation were given to fed or fasted volunteers. These data indicate that the controlled release formulation produces plasma concentrations of diazepam and N-desmethyldiazepam comparable to those achieved with the same daily dose of the trade product given three times daily, suggesting that these regimens can be used interchangeably.Diazepam/Roche is marketed under the trade name Valium^®.