Pharmacokinetics of CGP 6140 (amocarzine) after oral administration of single 100-1600 mg doses to patients with onchocerciasis.

The concentrations of CGP 6140 [4-nitro-4'-(N-methyl-piperazinylthiocarbonylamido)-diphenylamine] and of its N-oxide metabolite, CGP 13,231, were measured in plasma and urine after single oral dose of 100-1600 mg of CGP 6140 to 41 fasted Ghanaian patients with Onchocerca volvulus infections. The absorption of CGP 6140 was rapid and its terminal elimination half-life was about 3 h. The plasma concentrations of CGP 6140 were essentially proportional to the dose. A greater variability in plasma concentrations was apparent after the 800 and 1600 mg doses indicating a poor bioavailability of the drug administered in fasting conditions to several patients. In plasma, the concentrations of CGP 13,231 were similar to those of CGP 6140. The amount of CGP 13,231 excreted in urine was 25-40% of the dose of CGP 6140 whereas only 1.5% was excreted as unchanged drug. If a single dose of drug is used for the treatment, the plasma concentration would be maintained for 3-4 h at a high level. At 8 h, the concentration falls to about 10% of the Cmax. If sustained plasma concentrations of the drug are needed for efficacy, twice daily administration would maintain the minimum concentration at about 10% of the Cmax.     

Pharmacokinetics of halofantrine in man: effects of food and dose size.

1. Plasma concentrations of halofantrine (Hf) and its putative principal plasma metabolite desbutyl halofantrine (Hfm) have been measured in two separate studies after oral administration of the hydrochloride salt. 2. Six healthy male volunteers each received single oral doses of 250, 500 and 1000 mg administered after an overnight fast. A washout period of at least 6 weeks was allowed between each dose. A further 250 mg single oral dose was administered to the same six subjects in a fasting state and after a standardised fatty meal in a randomised study, again with a washout period of at least 6 weeks. 3. AUC and maximum plasma concentration (Cmax) for Hf increased in proportion to the dose from 250-500 mg. This increase was non-proportional when the dose was increased from 500 to 1000 mg. For Hfm, in the dose range 250-500 mg, AUC but not Cmax increased in proportion in the increase in dose size. The increase in these parameters was non-proportional when the dose was increased from 500 to 1000 mg. Time to reach peak concentrations for Hf and Hfm and the elimination half-life of Hf remained unchanged across the dosage range. 4. Following a fatty meal, Cmax for Hf was increased from 184 +/- 115 micrograms l-1 (fasting) to 1218 +/- 464 micrograms l-1 (fed). AUC for Hf was increased from 3.9 +/- 2.6 mg l-1 h (fasting) to 11.3 +/- 3.5 mg l-1 h following a fatty meal.(ABSTRACT TRUNCATED AT 250 WORDS)     

Lack of effect of antacids on plasma concentrations of omeprazole given as enteric-coated granules.

Twelve male volunteers were studied after a single oral dose of 20 mg omeprazole given as enteric-coated granules with and without concomitant administration of 10 ml of a potent liquid antacid (buffering capacity 56.6 mmol 10 ml-1) under fasting conditions. No statistically significant differences were detected in median Cmax (0.41 approximately equal to 0.53 mumol l-1), the geometric mean AUC (0.80 approximately equal to 0.81 mumol l-1 h) or median tmax (1.25 h), with and without antacid.     

Pharmacokinetic evaluation of a new oral sustained release dosage form of tramadol

AIMS: To compare the pharmacokinetic profile of a new modified release formulation of tramadol (Tramadol LP 200 mg, SMB Technology, Marche-en-Famenne, Belgium) with that of an immediate release capsule (Topalgic) 50 mg, Grünenthal, Aachen, Germany) after single and multiple dosing and to assess the potential effect of food on its relative bioavailability. METHODS: The first study had an open, single-dose, three-treatment, three-period, six-sequence, randomised, crossover design with at least a five-day wash-out. The second study had an open, steady-state, two-treatment, two-period, two-sequence, randomised crossover design with at least a seven-day wash-out. Both studies contained 30 healthy subjects. Both enantiomers of tramadol and O-demethyl-tramadol (the only active metabolite of tramadol) were assayed in the plasma using an LC-MS/MS method. AUC infinity, AUCt, Cmax, Tmax, and T1/2 were estimated. Statistical analysis was performed using univariate anova, the Wilcoxon nonparametric method or Friedman's nonparametric anova where appropriate. RESULTS: Tramadol had a significantly lower Cmax and longer Tmax than the conventional formulation. Thus, the mean (+/- sd) Cmax of tramadol were 646 +/- 192 and 300 +/- 94 ng ml-1 for Topalgic 4 x 50mg and Tramadol LP 200 mg, respectively (95% confidence interval on the difference expressed as a percentage 42-51). AUC of tramadol from both formulations was comparable (similar AUC infinity and AUCt). Thus, the mean AUC infinity of (+/-)tramadol obtained after multiple dosing were 4611 +/- 1944 and 5105 +/- 2101 ngh ml-1 after Topalgic 4 x 50mg and Tramadol LP 200 mg, respectively (95%CI 102-123%). We also demonstrate that the pharmacokinetics of the drug are not influenced by the intake of food. Thus, the mean AUC infinity of (+/-) tramadol were 5444 +/- 1637 and 5169 +/- 1580 ngh ml-1 after Tramadol LP 200 mg given in the fasting and fed states, respectively (95%CI = 88-103%). CONCLUSIONS: The new sustained release form of tramadol exhibits adequate properties for once a day administration. Furthermore, its pharmacokinetic profile is not affected by the intake of food.     

Interactions among primaquine, malaria infection and other antimalarials in Thai subjects.

1. The pharmacokinetics of rac-primaquine (45 mg base) and its principal plasma metabolite, carboxyprimaquine have been investigated in healthy Thai adults prior to and following a single oral dose of mefloquine (10 mg kg-1). 2. Primaquine was rapidly absorbed, attaining peak plasma concentrations (median and range) of 167 (113-532) micrograms l-1 in 2 (1-4) h. Thereafter, concentrations declined rapidly with an apparent terminal half-life of 6.1 (1.7-16.1) h and an oral clearance (CLpo) of 33.1 (17.6-49.3) l h-1. Administration of mefloquine had no effect on the values of any of these parameters at the 5% level of significance [Cmax 229 (114-503) micrograms l-1; tmax 3 (2-4) h; t1/2,z 3.9 (1.7-13.5) h; CLpo 34.0 (21.7-49.0) l h-1]. 3. The carboxylic acid metabolite of primaquine achieved maximum concentrations (median and range) of 890 (553-3634) micrograms l-1 at 6 (3-16) h. Thereafter, plasma concentrations of carboxyprimaquine declined to 346 (99-918) micrograms l-1 at 24 h. AUC (0,24 h) was 12737 (6837-27388) micrograms l-1 h. Administration of mefloquine had no effect on the plasma concentrations of this metabolite [Cmax 1035 (174-3015) micrograms l-1; tmax 8 (2-24) h; AUC(0,24) 13471 (2132-17863) micrograms l-1 h]. 4. The effect of falciparum malaria and treatment with quinine (10 mg salt kg-1 p.o.) on the pharmacokinetics of primaquine (45 mg base p.o.) has been investigated in adult Thai patients during and after infection with falciparum malaria.(ABSTRACT TRUNCATED AT 250 WORDS)     

Bioequivalence study of two losartan formulations administered orally in healthy male volunteers

The bioavailability of a new losartan preparation (2-butyl-4-chloro-1-[p-(o-1H-tetrazol-5-ylphenyl)benzyl]imidazole-5-methanol monopotassium salt, CAS 114798-26-4) was compared with the reference preparation of the drug in 24 healthy male volunteers, aged between 19 and 32. The open, randomized, single-blind two-sequence, two-period crossover study design was performed. Under fasting conditions, each subject received a single oral dose of 100 mg losartan as a test or reference formulation. The plasma concentrations of losartan and its active metabolite were analyzed by a rapid and sensitive HPLC method with UV detection. The pharmacokinetic parameters included AUC0-36h, AUC0-infinity, Cmax, t1/2, and Ke. Values of AUC0-infinity demonstrate nearly identical bioavailability of losartan from the examined formulations. The AUC0-infinity of losartan was 2019.92+/-1002.90 and 2028.58+/-837.45 ng x h/ml for the test and reference formulation, respectively. The AUC0-infinity of the metabolite was 10851.52+/-4438.66 and 11041.18 +/-5015.81 ng x h/ml for test and reference formulation, respectively. The maximum plasma concentration (Cmax) of losartan was 745.94+/-419.75 ng/ml for the test and 745.74+/-329.99 ng/ml for the reference product and the Cmax of the metabolite was 1805.77+/-765.39 and 1606.22 +/-977.22 ng/ml for the test and reference product, respectively. No statistical differences were observed for Cmax and the area under the plasma concentration-time curve for both losartan and its active metabolite. 90 % confidence limits calculated for Cmax and AUC from zero to infinity (AUC0-infinity) of losartan and its metabolite were included in the bioequivalence range (0.8-1.25 for AUC). This study shows that the test formulation is bioequivalent to the reference formulation for losartan and its main active metabolite.     

Pharmacokinetics of the individual enantiomers of vigabatrin (gamma-vinyl GABA) in epileptic children.

1. The pharmacokinetics of the enantiomers of vigabatrin were investigated after oral administration of a single 50 mg kg-1 dose of the racemate to two groups of six epileptic children (I: 5 months-2 years, II: 4-14 years). 2. The mean (+/- s.d.) values of maximum plasma concentration and area under the plasma concentration-time curve of the R(-) enantiomer were significantly higher than those of S(+) vigabatrin in both groups: R(-) Cmax: 21 +/- 6.6 (I)-41.3 +/- 13.9 (II) vs S(+) Cmax: 13.9 +/- 4.5 (I)-23.8 +/- 12.2 (II) mg l-1; R(-) AUC: 106 +/- 28.5 (I)-147 +/- 34 (II) vs S(+) AUC: 90.9 +/- 27.9 (I)-117 +/- 26 (II) mg l-1 h. In group I, the half-life of the R(-) isomer was significantly shorter than that of the S(+) isomer; in group II, the half-lives were comparable. 3. For the R(-) enantiomer the area under the curve, and the elimination half-life increased linearly with age. 4. During chronic administration (50 mg kg-1 vigabatrin racemate twice a day for 4 days), the morning trough plasma drug concentrations did not increase.     

Impact of gastric emptying on the pharmacokinetics of ethanol as influenced by cisapride

AIMS: To examine the influence of cisapride on the pharmacokinetics of ethanol and the impact of gastric emptying monitored by the paracetamol absorption test. METHODS: Ten healthy male volunteers took part in a cross-over design experiment. They drank a moderate dose of ethanol 0.30 g kg-1 body weight exactly 1 h after eating breakfast either without any prior drug treatment or after taking cisapride (10 mg three times daily) for 4 consecutive days. In a separate study, the same dose of ethanol was ingested on an empty stomach (overnight fast). Paracetamol (1.5 g) was administered before consumption of ethanol to monitor gastric emptying. Venous blood was obtained at 5-10 min intervals for determination of ethanol by headspace gas chromatography and paracetamol was analysed in serum by high performance liquid chromatography (h.p.l.c.). Results The maximum blood-ethanol concentration (Cmax ) increased from 3.8+/-1.7 to 5.6+/-2.3 mmol l-1 (+/-s.d.) after treatment with cisapride (95% confidence interval CI on mean difference 0.28-3.28 mmol l-1 ). The area under the blood-ethanol curve (AUC) increased from 6.3+/-3.5 to 7.9+/-2.6 mmol l-1 h after cisapride (95% CI -0. 74-3.9 mmol l-1 h). The mean blood ethanol curves in the cisapride and no-drug sessions converged at approximately 2 h after the start of drinking. Both Cmax and AUC were highest when the ethanol was ingested on an empty stomach (Cmax 9.5+/-1.7 mmol l-1 and AUC 14. 6+/-1.9 mmol l-1 h), compared with drinking 1 h after a meal and regardless of pretreatment with cisapride. CONCLUSIONS: A small but statistically significant increase in Cmax occurred after treatment with cisapride owing to faster gastric emptying rate as shown by the paracetamol absorption test. However, the rate of absorption of ethanol, as reflected in Cmax and AUC, was greatest after drinking the alcohol on an empty stomach. The cisapride-ethanol interaction probably lacks any clinical or forensic significance.     

Absence of food effect on the pharmacokinetics of telbivudine following oral administration in healthy subjects

The influence of food on the pharmacokinetics of telbivudine, a candidate antiviral agent against hepatitis B virus (HBV), was investigated in healthy adult subjects following a 600-mg oral dose administered with and without a high-fat/high-calorie meal. Telbivudine was well tolerated under fasting and fed conditions. Oral absorption of telbivudine as measured by maximum plasma concentration (Cmax), time to reach Cmax (Tmax), and area under the plasma concentration-time curve (AUC(0-t) and AUC(0-infinity)) was not altered by food intake immediately before oral dosing. Values of Cmax, Tmax, and AUC were comparable when telbivudine was administered under fed and fasting conditions. Results from this study indicated that the absorption of telbivudine was not affected by a high-fat/high-calorie meal; telbivudine can therefore be administered orally with no regard to the timing of meals.     

6-Thioguanine in children with acute lymphoblastic leukaemia: influence of food on parent drug pharmacokinetics and 6-thioguanine nucleotide concentrations

AIMS: Since relatively little is known about the pharmacokinetics of 6-thioguanine (6TG) in children receiving 6-thioguanine for maintenance therapy of acute lymphoblastic leukaemia (ALL), we studied plasma drug concentrations under standardized conditions and investigated the effect of food on parent drug pharmacokinetics and the accumulation of the active metabolites 6-thioguanine nucleotides (6-TGNs) in red cells. METHODS: Single oral doses of 40 mg of 6-TG were administered both in the fasting and fed state to children with ALL. Pharmacokinetic sampling was performed up to 6 h post dose. Daily oral doses of 40 mg m(-2) of 6-TG were administered both fasting and after food over two 4 week periods. Twice weekly samples were taken for metabolite concentrations. The study design was cross-over with each child receiving dosing in either fasted or after food over a 4 week period in each phase. RESULTS: Eleven patients were studied. A wide interindividual variation in Cmax (median 313 pmol ml(-1), range 51-737) and AUC (median 586 pmol ml(-1) h, range 156-1306) was observed in the fasted state. Concomitant food administration resulted in a significant reduction in Cmax (median 71 vs 313 pmol ml(-1), P = 0.006, CI from 36 to 426), AUC (median 200 vs 586 pmol ml(-1) h, P = 0.006, 95% CI from 109 to 692), and time to reach Cmax (median 1.5 vs 3 h, P = 0.013, 95% CI from 0.74 to 2.73). There was no difference in the steady state concentration of red cell 6-TGNs observed after a 4 week period of 6-TG administered fasting or after food. CONCLUSIONS: Children with ALL demonstrate significant interindividual variation in 6-TG pharmacokinetics. Although there would appear to be a reduction in parent drug Cmax and AUC with food there was no difference in 6-TGN concentrations after 4 weeks of 6-TG. Taking the drug on an empty stomach may not be necessary.     

Pharmacokinetics of halofantrine in Thai patients with acute uncomplicated falciparum malaria.

Twelve patients with acute uncomplicated falciparum malaria were admitted to the Hospital for Tropical Diseases for 42 days. The patients were treated with halofantrine 500 mg 6 hourly for three doses and halofantrine and its desbutyl metabolite were analysed in plasma by h.p.l.c. Cmax values of halofantrine and desbutylhalofantrine (n = 12) were 1192 +/- 410 (mean +/- s.d.) and 397 +/- 160 ng ml-1 with tmax values of 16 +/- 2 and 55 +/- 26 h, respectively. AUC was 60.6 +/- 23.9 and 48.5 +/- 22.2 mg l-1 h, respectively, for halofantrine and its metabolite. Halofantrine cured 83% of the patients but in two patients a reduction only in asexual parasitaemia was seen and no overall parasite clearance occurred. One of these, however had relatively low plasma concentrations of both halofantrine and its desbutyl metabolite and it appeared to be a case of inadequate treatment rather than true resistance. We suggest that the large intersubject variability in plasma drug concentrations may relate in part to its poor and inconsistent bioavailability and this rather than true resistance might be responsible for some of the treatment failures.     

Pharmacokinetics of SDZ RAD and cyclosporin including their metabolites in seven kidney graft patients after the first dose of SDZ RAD

AIMS: The aim of the study was to investigate the pharmacokinetics and metabolism of the new immunosuppressant SDZ RAD during concomitant therapy with cyclosporin in stable renal transplant patients. Furthermore, we studied the influence of SDZ RAD on the pharmacokinetics of cyclosporin at steady state levels. METHODS: SDZ RAD was administered orally in different doses (0.25-15 mg day-1) to seven patients, who were on standard cyclosporin-based immunosuppression. The blood concentrations of both drugs including their main groups of metabolites were measured simultaneously by LC/electrospray-mass spectrometry. RESULTS: The mean area under the blood concentration-time curve to 12 h (AUC(0,12 h)) was 4244 +/- 1311 microg l-1 h for cyclosporin before SDZ RAD treatment and 4683 +/- 1174 microg l-1 h (P = 0.106) on the day of SDZ RAD treatment (95% CI for difference -126, 1003). On both study days Cmax, and tmax of cyclosporin were not significantly different. The metabolite pattern of cyclosporin did not change. The pharmacokinetic data of SDZ RAD dose-normalized to 1 mg SDZ RAD were as follows: AUC(0,24 h): 35.4 +/- 13.1 microg l-1 h, Cmax: 7.9 +/- 2.7 microg l-1 and tmax: 1.5 +/- 0.9 h. The metabolites of SDZ RAD found in blood were hydroxy-SDZ RAD, dihydroxy-SDZ RAD, demethyl-SDZ RAD, and a ring-opened form of SDZ RAD. CONCLUSIONS: A single dose of SDZ RAD did not influence significantly the pharmacokinetics of cyclosporin. The most important metabolite of SDZ RAD was the hydroxy-SDZ RAD, its AUC(0,24 h) being nearly half that of the parent compound SDZ RAD.     

Lack of effect of food on the pharmacokinetics of an extended-release oxybutynin formulation

The effect of food on the pharmacokinetics of 15 mg oxybutynin XL was evaluated in a single-dose, randomized, crossover, open-label study in healthy volunteers. A validated, stereospecific, high-performance liquid chromatography assay was used to simultaneously determine the plasma concentrations of R- and S-oxybutynin and active metabolite R- and S-desethyloxybutynin. The mean AUC and Cmax values for each of the four analytes in the fed treatment were within +/- 20% of the fasting treatment values. The 90% confidence intervals for the treatment ratios (fed/fasted) for log-transformed Cmax and AUCinf values for the drug isomers and AUCinf values for the metabolite isomers were all within the 80% to 125% range. Only the ranges for the Cmax values for R- and S-desethyloxybutynin were slightly wider but were well within the 70% to 143% criteria recommended for Cmax when comparing effect of food. Lack of effect of food on oxybutynin XL is consistent with the previous observation that the osmotically controlled formulations are nearly insensitive to the gastrointestinal environment, including food. Oxybutynin XL was well tolerated, and the safety results were comparable whether administered alone or with food. In conclusion, oxybutynin XL administration does not require any caution to be exercised regarding food.     

Pharmacokinetics of extended-release and immediate-release formulations of galantamine at steady state in healthy volunteers

OBJECTIVE: To assess the steady-state galantamine (GAL) bioavailability of the extended-release 24-mg qd capsule (GAL-ER) with and without food and to evaluate the relative bioavailability of GAL-ER with the immediate-release 12-mg bid tablet (GAL-IR) at steady state. METHODS: This was a single-center, open-label, randomized, 3-way crossover study in 24 healthy volunteers (12 males and 12 females) aged 18 to 45 years. After 7 days of GAL-ER 8 mg qd each morning and 7 days of GAL-ER 16 mg qd each morning, subjects received the following treatments in randomized, crossover order (7 days each): GAL-ER 24 mg qd each morning (fasted before Day 7 morning dose), GAL-ER 24 mg qd each morning (fed before Day 7 morning dose), and GAL-IR 12 mg bid (fasted before Day 7). Pharmacokinetic parameters of GAL at steady state were determined after morning intake on Day 7 of each treatment week. Safety evaluations included adverse event (AE) reporting, physical examination, clinical laboratory tests, vital signs, and electrocardiography. RESULTS: The treatment ratios of area under the plasma concentration-time curve of GAL from time 0-24 h post-dosing (AUC24 h), peak plasma concentration (Cmax), and pre-dose plasma concentration (Cmin) for GAL-ER fed/fasting were 105%, 112%, and 103%, respectively. The treatment ratios and 90% confidence intervals for all above mentioned pharmacokinetic parameters demonstrated bioequivalence (with the range of 80-125%), indicating that food had no effect on GAL-ER bioavailability. As anticipated, GAL-ER (fasting) had mean AUC24 h similar to GAL-IR (fasting), with lower Cmax (63 ng/mL vs 84 ng/mL) and longer time to reach Cmax (4.4 h vs 1.2 h). The treatment ratios and 90% confidence intervals for both AUC24 h and Cmin demonstrated bioequivalence (within the range of 80-125%). The treatment ratio for Cmax was 75.7%, indicating a 24% lower Cmax for GAL-ER than for GAL-IR. In this study, GAL-ER was safe and well tolerated with or without food and was comparable to the GAL-IR formulation. CONCLUSION: Food had no effect on the GAL bioavailability of GAL-ER at steady state. GAL-ER was bioequivalent to GAL-IR with respect to AUC24 h and Cmin.     

Effect of food intake on the bioavailability of almotriptan, an antimigraine compound, in healthy volunteers: an open, randomized, crossover, single-dose clinical trial

This open, randomized, crossover, single-dose clinical trial evaluated the possible pharmacokinetic interaction between a single oral dose of almotriptan 25 mg, a 5-HT1B/1D receptor agonist for the acute treatment of migraine, and food intake in healthy volunteers. The influence of food intake in the rate and extent of almotriptan absorption was evaluated by bioequivalence criteria. Tolerability and safety of treatment were also assessed. 16 healthy volunteers (8 men and 8 women, aged 19-27 years) received a crossed single oral dose of almotriptan 25 mg under fasting and fed conditions, separated by a 7-day washout period. The treatment given under fasting condition was considered as reference. Plasma levels of almotriptan were analyzed using high-performance liquid chromatography (HPLC) and UV detection at 227 nm. The 90% confidence intervals (CI) for the logarithmically transformed Cmax and AUC0-infinity, values of almotriptan under fasting and fed conditions (97.8 - 124% and 102.9 - 108.2%, respectively) fell into the predetermined accepted range of 80 - 125%. No statistically significant differences in Cmax, tmax, AUC0-infinity, MRT and t1/2 were observed under fasting and fed conditions between men and women. Tolerability of treatments was good throughout the whole study period. In conclusion, administration of almotriptan 25 mg is bioequivalent under fasting and fed conditions in healthy men and women. Therefore, it is unlikely that concomitant food intake would produce clinially relevant differences in therapeutic effect with almotriptan at the dose studied here.     

The relative bioavailability study and fasting and fed states pharmacokinetics of bicalutamide 50-mg tablets in healthy Chinese volunteers

The aim of this study was to evaluate the bioequivalence of a new generic formulation of bicalutamide 50-mg tablets (test) and the available branded formulation (reference) to comply with regulatory criteria for marketing of the test product in China. This single-dose, randomized-sequence, open-label, 2-period crossover study was conducted in 40 healthy male volunteers and consisted of separate fasting and fed phases. A single oral dose of the test or reference formulation was followed by a 6-week washout period, after which subjects received the alternative formulation. Blood samples were collected before dosing and at 0.5, 1, 2, 4, 8, 12, 15, 24, 30, 36, 48, 72, 144, 288, 432 and 576?h after dosing. Plasma samples were separated and assayed for bicalutamide using a selective and sensitive HPLC method with UV detection. The fasting and fed states pharmacokinetic parameters AUC0-576?h, AUC0-∞, Cmax, tmax and t1/2 were determined from plasma concentration-time profile of both formulations. The formulations were considered bioequivalent when the 90% CIs of the geometric mean ratios (test:reference) for Cmax and AUC0-576?h were within the regulatory range of 80-125%. There were no significant increases in bicalutamide Cmax, AUC0-576?h or tmax for either formulation in the fed phase compared with the fasting phase. In both the fasting and fed portions of the study, the 90% CIs for the ratio (test:reference) of log-transformed Cmax and AUC0-576?h were within the acceptance range for bioequivalence.     

Moexipril shows a long duration of action related to an extended pharmacokinetic half-life and prolonged ACE inhibition

OBJECTIVE: To characterize the lipophilic ACE inhibitor moexipril and its active metabolite moexiprilat regarding the duration of action, the susceptibility of the pharmacokinetics and pharmacodynamics to food intake and the concentration-dependent effect. METHODS: Three independent, open, randomized studies were performed in healthy subjects using crossover or parallel-group designs. In the first study, pharmacokinetics (AUC, Cmax, tmax, t 1/2) and ACE inhibition (up to 72 h) were investigated following single oral doses of 15 mg moexipril administered in the fasting and postprandial state (n = 24). The individual ACE inhibition data and plasma concentration data were fitted to an Emax model. In the second study, carried out in 52 volunteers, the pharmacokinetics were followed over 36 h following administration of 2 single oral doses of 15 mg moexipril. In the third study, the pharmacokinetics after multiple dosing of 15 mg moexipril once daily for 5 days were investigated in 12 young and 12 elderly subjects. RESULTS: Moexiprilat tmax was 1.5-2 h with only minor differences between single and multiple dosing. Compared to fasting, the postprandial moexiprilat Cmax and AUC (ratio fed/fasted 58.0%; 90% CI 52.2-64.5%) were distinctly reduced (ANOVA p = 0.0001). Moexiprilat showed a biphasic elimination phase with an average t 1/2 of 29-30 h. In contrast to the alpha-phase, the plasma concentrations during the terminal elimination phase were not affected by food. A relationship between ACE inhibition and plasma concentration was not observed. The average ACE inhibition over 72 h was 71 % in the fasting state and 74% in the postprandial state. ACE inhibition increased to about 80% after 24 h and decreased to about 60% at 72 h. The S-shaped concentration-effect curve indicated that a moexiprilat level of 1.3 ng/ml was sufficient to produce 50% inhibition of ACE. With repeated dosing there were no signs of drug accumulation and day-to-day drug levels were relatively constant. The trough concentrations at 24 h did not fall below the limit of 1-2 ng/ml, i.e. a 50% ACE inhibition. CONCLUSION: Moexiprilat showed an extended duration of action owing to a long terminal pharmacokinetic half-life and produced a persistent ACE inhibition. Although the pharmacokinetics were partly influenced by food intake, ACE inhibition was not affected. This might be explained by a second compartment directly related to the ACE which is less prone to food effects and the reaching of a ceiling in the sigmoidal concentration-effect curve even with the lower Cmax concentrations associated with the postprandial state.     

Influence of food on the absorption of the p-chlorophenolic ester of chlorophenoxyisobutyric acid in man.

A study was designed to investigate the effect of a fatty meal on the absorption of chlorophenoxyisobutyric acid (CPIB) in six healthy adult volunteers after oral administration of the p-chlorophenolic (PCP) ester of CPIB. Plasma concentrations of CPIB when administered with food were higher than those observed in the fasting state. The Cmax in the former case was 24.0 +/- 4.6 mg l-1 as against a value of 15.2 +/- 6.9 mg l-1 in the latter (P less than 0.01). The pharmacokinetic parameters measured were found to be linear with the dose administered. This could be due to low plasma concentrations of CPIB unable to cause a saturation of the plasma protein binding of this drug. It is concluded that a fatty meal enhances the absorption of this hypolipidaemic drug.     

Bioavailability of a new sustained-release theophylline capsule in fasted and non-fasted healthy subjects: single and multiple dosing studies

Eighteen healthy, non-smoking, adult volunteers participated in single and multiple dose three-way crossover studies to evaluate a sustained-release, pellet-filled capsule of theophylline, Austyn. The effect of food on the bioavailability of the sustained-release capsule was investigated by administering 300 mg single doses of Austyn, with a high-fat meal and without food and a divided 300 mg dose of the reference product Elixophyllin elixir, given after fasting. Plasma theophylline concentrations were measured by fluorescence polarization immunoassay (FPIA) which had been validated against HPLC. The single dose study data showed that there were no significant differences (n = 18, ANOVA, p greater than 0.05) between the three regimens with respect to AUC0-infinity values (mg h l-1), (mean +/- SD); Elixophyllin fasting = 97.1 +/- 33.7, Austyn with food = 90.9 +/- 31.3, Austyn fasting = 91.2 +/- 33.8. Similarly, multiple dosing with rapid-release Nuelin tablets, Austyn capsules, and sustained-release Theo-Dur tablets demonstrated that there were no significant differences between regimens with respect to AUC0-24h, AUC0-12h, and AUC12-24h values calculated from the steady-state concentrations (5th day, 24 h sampling). However, the percentage fluctuation at steady-state over the total blood sampling period was significantly less for treatment with the sustained-release capsule. Austyn, compared with the sustained-release tablet, Theo-Dur (Austyn = 36.7 +/- 13.7 per cent, Theo-Dur = 53.1 +/- 14.1 per cent). The results of the single and multiple dose studies indicate that Austyn capsules demonstrate complete bioavailability, and good controlled release characteristics not influenced by concomitant intake of a high-fat meal and with no evidence of dose dumping.     

Pharmacokinetics of sarizotan after oral administration of single and repeat doses in healthy subjects

OBJECTIVE: Sarizotan is a 5-HTIA receptor agonist with high affinity for D3 and D4 receptors. Here we report the pharmacokinetic and tolerability results from four Phase 1 studies. MATERIALS: Two single-dose (5 -25 mg, n = 25, 0.5 - 5 mg, n = 16) and two multiple-dose (10 and 20 mg b.i.d., n = 30, 5 mg b.i.d., n = 12) studies with orally administered sarizotan HCl were carried out in healthy subjects. METHODS: Plasma sarizotan HCl concentrations were measured using a validated HPLC method and fluorescence or MS/MS detection. Pharmacokinetic parameters were obtained using standard non-compartmental methods. RESULTS: Sarizotan was rapidly absorbed, group-median times to reach maximum concentration (tmax) ranged from 0.5 -2.25 h after single doses and during steady state. Maximum plasma concentration (Cmax) and tmax were slightly dependent on formulation and food intake, whereas area under the curve (AUC) was unaffected by these factors. AUC and Cmax increased dose-proportionally over the tested dose range. Independently of dose and time, sarizotan HCl plasma concentrations declined polyexponentially with a terminal elimination half-life (t1/2) of 5 - 7 h. Accumulation factors corresponded to t1/2 values, and steady state was reached within 24 h. Plasma metabolite concentrations were considerably lower than those of the parent drug. The ratio metabolite AUC : parent drug AUC was time- and dose-independent for all three metabolites suggesting that the metabolism of sarizotan is non-saturable in the tested dose range. CONCLUSIONS: The pharmacokinetics of sarizotan were dose-proportional and time-independent for the dose range 0.5 -25 mg). The drug was well-tolerated by healthy subjects up to a single dose of 20 mg.