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Biomedical subjects

J H Cavanaugh

Publications and source records attributed to J H Cavanaugh.

At least 19 recordsLinked to original sources

Effect on bioavailability of admixing the contents of lansoprazole capsules with selected soft foods.

OBJECTIVE: This study was designed to compare the bioavailability of lansoprazole when administered as an intact capsule and when the contents are admixed with various soft foods. BACKGROUND: Patients sometimes cannot swallow or have difficulty swallowing intact capsules such as lansoprazole. To enable them to ingest the drug, the contents of the capsule can be admixed with small amounts of soft foods. METHODS: Twenty-four healthy adult volunteers participated in this single-dose, 4-period crossover study by ingesting the contents of a 30-mg lansoprazole capsule that had been emptied into either a tablespoon of yogurt (regimen A), Ensure pudding (regimen B), or cottage cheese (regimen C), or given as an intact capsule (regimen D) during the first study period. The regimen assignments were rotated at weekly intervals so that each subject received each regimen. Blood samples were obtained over the 12-hour period after administration of each regimen, and pharmacokinetic parameters were determined. RESULTS: Of the 23 subjects who completed all 4 periods of the study, 18 were male and 5 were female. Their mean (+/- SD) age was 33.3+/-11.6 years, and their ages ranged from 19 to 52 years. No statistically significant differences between regimens were detected in mean maximum concentration, area under the curve (AUC) from time zero to the last measurable concentration, and AUC from time zero to infinity (AUC0-infinity) using analysis of variance. A statistically significant difference was detected in the time to maximum concentration between regimens C and D at 2.1 and 1.5 hours, respectively (P < or = 0.05). Bioavailability was assessed by the two 1-sided tests procedure using a 90% CI for the AUC0-infinity ratio of test-to-reference regimens. The 90% CIs were all within an acceptable equivalence range of 0.80 to 1.25. CONCLUSION: These results indicate similar bioavailabilities between the regimen in which the lansoprazole capsule was emptied and administration of the intact capsule. However, they may have limitations in predicting the results in ill, elderly, or very young patients.

2-Pyridinylmethylsulfinylbenzimidazoles↗

Lack of interaction between lansoprazole and propranolol, a pharmacokinetic and safety assessment.

Due to the prevalence of both gastrointestinal and cardiovascular diseases, it is likely that patients may be coprescribed gastric parietal cell proton pump inhibitors and beta-adrenergic antagonists. Therefore, the objectives of this phase I study were to assess the potential effects of the coadministration of lansoprazole on the pharmacokinetics of propranolol and to evaluate the safety of propranolol with concomitant lansoprazole dosing. In a double-blind fashion, 18 healthy male nonsmokers were initially randomized to receive either 60 mg oral lansoprazole, each morning for 7 days, or an identical placebo (period 1). On day 7, all subjects were concomitantly administered oral propranolol, 80 mg. After a minimum of 1 week following the last dose of either lansoprazole or placebo, subjects were crossed over to the opposite treatment for another 7 days (period 2). Subjects were again administered oral propranolol on day 7. During both treatment periods, blood samples for the determination of plasma propranolol and 4-hydroxy-propranolol were obtained just before the dose and at 0.5, 1, 2, 3, 4, 6, 8 12, 16, 20, and 24 hours postdose. Plasma propranolol and 4-hydroxy-propranolol concentrations were determined by using HPLC with fluorescence detection. The Cmax, tmax, AUC0-infinity, and t1/2 values for propranolol, as well as the AUC0-infinity for 4-hydroxy-propranolol, were calculated and compared between the lansoprazole and placebo regimens. The mean age of the 15 subjects who successfully completed the study was 31 years (range: 24-38 years), and their average weight was 174.8 pounds (range: 145-203 pounds). There were no statistically significant differences between the lansoprazole and placebo regimens for the propranolol Cmax, tmax, AUC0-infinity, and t1/2 values. Also, there were no statistically significant differences between regimens for the 4-OH-propranolol AUC0-infinity. Safety evaluations, which included adverse events, vital signs, clinical laboratory determinations, ECG, and physical examinations, revealed no unexpected clinically significant findings and did not suggest a drug-drug interaction. In conclusion, lansoprazole does not significantly alter the pharmacokinetics of propranolol, suggesting that it does not interact with the CYP2D6- or CYP2C19-mediated metabolism of propranolol. Modification of a propranolol dosage regimen in the presence of lansoprazole is not indicated, based on the pharmacokinetic analysis and the lack of a clinically significant alteration in the pharmacodynamic response.

2-Pyridinylmethylsulfinylbenzimidazoles↗

Lack of pharmacokinetic interaction between lansoprazole and intravenously administered phenytoin.

The objective of this randomized, double-blind, two-period crossover study was to investigate whether concomitant steady-state lansoprazole influences the pharmacokinetics of CYP2C9 substrates using single intravenously dosed phenytoin as a model substrate. In addition, the safety of concomitant administration of these two drugs was evaluated. Twelve healthy, nonsmoking, adult male subjects received 60 mg lansoprazole or placebo once daily for 9 days during each study period. On the morning of day 7, each subject received a single 250 mg intravenous phenytoin dose. There were no statistically significant differences between the two regimens for mean phenytoin Cmax or tmax. There was a minor (< 3%) but statistically significant difference between the two regimens for phenytoin AUC resulting from a very low intrasubject coefficient of variation (2.3%). The treatment and control mean plasma concentration phenytoin profiles were virtually super-imposable. In conclusion, concomitant multidose lansoprazole administration is unlikely to have any clinically significant effect on the pharmacokinetics of CYP2C9 substrates in general or intravenous phenytoin specifically.

2-Pyridinylmethylsulfinylbenzimidazoles↗

Effect of ritonavir on the pharmacokinetics of ethinyl oestradiol in healthy female volunteers.

AIMS: To assess the effects of the protease inhibitor ritonavir on the pharmacokinetics of ethinyl oestradiol in healthy female volunteers. METHODS: This was an open-label, single centre study in 23 subjects who received two single doses of oral contraceptive containing 50 microg ethinyl oestradiol on Day 1 (alone) and on Day 29 during concomitant ritonavir. Each subject received 16 days of every 12 h doses of ritonavir from Day 15 through Day 30. Blood samples were collected for serum ethinyl oestradiol concentrations for 48 h after each dose and for plasma ritonavir on Day 29 at 0 and 4 h postdose. RESULTS: Statistically significant decreases in ethinyl oestradiol mean Cmax (-32%) and mean AUC (-41%), and a statistically significant increase in the mean terminal elimination rate constant (+31%) were observed during concomitant ritonavir. The harmonic mean terminal half-life decreased from 17 h to 13 h during concomitant ritonavir. No statistically significant change was noted in tmax. The ratios of means (95% confidence intervals) for Cmax and AUC were 0.682 (0.612-0.758) and 0.595 (0.506-0.694), respectively. The changes in ethinyl oestradiol pharmacokinetics were consistent with an increase in clearance from enzymatic induction of glucuronidation and/or cytochrome P450 hydroxylation. Mean steady-state ritonavir concentrations of 6.5 and 13.4 microg ml(-1) were observed at 0 and 4 h postdose, respectively. CONCLUSIONS: Considering the extent of the decrease in ethinyl oestradiol concentrations, the use of alternate contraceptive measures should be considered when ritonavir is being administered.

Adult↗

Lack of cytochrome P450 1A2 interaction effect of ABT-761 on the pharmacokinetics of theophylline.

ABT-761 is a second-generation 5-lipoxygenase inhibitor for the treatment of asthma. The effects of ABT-761 on the pharmacokinetics of theophylline were assessed in 15 adult volunteers in a phase I, multiple-dose, open-label, one-period study. Subjects received a single 400-mg dose of theophylline on days 1 and 8 and 200-mg oral doses of ABT-761 once daily beginning on day 3 and continuing through day 9. The pharmacokinetic parameters of theophylline after administration of theophylline alone and concomitantly with ABT-761 were compared using a paired t-test. No statistically significant differences were observed between the pharmacokinetic parameters of theophylline administered alone and theophylline with concomitant administration of ABT-761. The 95% confidence interval for the ratio of the mean with ABT-761 dosing to the mean for theophylline alone was 0.970 to 1.127 for area under the plasma concentration-time curve and 0.887 to 1.036 for maximal plasma concentration. The lack of an inhibition effect by ABT-761 on theophylline clearance suggested that ABT-761 may have a low affinity for the cytochrome P450 1A2 isozyme, the primary isozyme responsible for theophylline metabolism.

Adult↗

Effect of fluoxetine on pharmacokinetics of ritonavir.

The potential interaction between fluoxetine, a known inhibitor of cytochrome P-450 isoform 2D6 (CYP2D6), and ritonavir, a human immunodeficiency virus type 1 protease inhibitor, was evaluated in this open-label study. Sixteen male and female subjects ranging in age from 18 to 40 years completed the study. Subjects received single doses of 600 mg of ritonavir on days 1 and 10. On study days 3 to 10, all subjects received 30 mg of fluoxetine every 12 h for a total of 16 consecutive doses. Serial blood samples for determination of ritonavir concentrations in plasma were collected after the administration of ritonavir on days 1 and 10. A limited number of blood samples for determination of fluoxetine and norfluoxetine concentrations were collected after administration of the morning dose on day 10. A statistically significant increase (19%) in the ritonavir area under the concentration-time curve (AUC) was observed with concomitant fluoxetine administration, with individual changes ranging from -12 to +56%. The change in the ritonavir AUC with concomitant fluoxetine administration was positively correlated with the norfluoxetine 24-h AUC (AUC24) (r2 = 0.42), the norfluoxetine/fluoxetine AUC24 ratio (r2 = 0.53), and the fluoxetine elimination rate constant (r2 = 0.65), with larger increases in the ritonavir AUC tending to occur with higher norfluoxetine concentrations and higher fluoxetine elimination rate constants. The effect of fluoxetine appeared to be larger in subjects with the CYP2D6 wt/wt genotype. There was little or no effect on the time to maximum drug concentration (Cmax) in serum, Cmax, and the elimination rate constant of ritonavir with concomitant fluoxetine administration. Considering the magnitude of the change observed, no ritonavir dose adjustment is recommended during concomitant fluoxetine administration.

Adolescent↗

Evaluation of the diurnal variation in the pharmacokinetics of zileuton in healthy volunteers.

The diurnal variation in the pharmacokinetic parameters of zileuton were evaluated in 12 healthy male volunteers in a three-period study. Periods I and II constituted a balanced, randomized, crossover study in which a participant received a single dose of 600-mg zileuton either at 7 AM or 11 PM. In period III all participants received 600-mg doses four times daily for 5 days. The differences between the pharmacokinetics of single doses of zileuton administered at 7 AM and 11 PM were not statistically significant. Plasma concentration-time profiles of zileuton during the four daily dose intervals at steady state were also similar. Values for the pharmacokinetic parameters of zileuton after multiple doses were similar to those after single doses, with a minimal accumulation of the drug after multiple doses. Overall, there was little or no diurnal variation in the pharmacokinetic parameters of zileuton after single and multiple doses.

Adolescent↗

Effect of valproate on the pharmacokinetics and pharmacodynamics of lorazepam.

The pharmacokinetic-pharmacodynamic interaction between valproate and lorazepam was evaluated in this randomized, double-blind, placebo-controlled crossover study. Sixteen healthy male volunteers enrolled in the study to receive either divalproex sodium (500 mg every 12 hours) or matching placebo for 12 days in the first period, and then to receive the other regimen for an identical second 12-day period. In both periods, lorazepam (1 mg every 12 hours) was administered on days 6 through 9 and on the morning of day 10. Concomitant administration of divalproex sodium with lorazepam resulted in an 8%, 20%, and 31% increase in steady-state maximum plasma concentration, area under the concentration-time curve, and trough plasma concentrations of lorazepam, respectively. The apparent clearance of lorazepam through the formation of lorazepam glucuronide was reduced by 31% during coadministration of divalproex sodium. Pharmacokinetic properties of valproate did not change significantly in the ten available participants during coadministration of lorazepam. Sedation scales revealed no statistically significant differences in sedation between the two regimens. It is concluded that valproate increases plasma concentrations and reduces clearance of lorazepam, most likely by impairing hepatic glucuronidation, and that coadministration of lorazepam does not affect the steady-state pharmacokinetic properties of valproate.

Adult↗

The pharmacokinetic and pharmacodynamic interaction between zileuton and terfenadine.

OBJECTIVES: The effects of zileuton on terfenadine pharmacokinetics, and the effects of terfenadine alone and the combination on the duration of the QTc interval and the morphology of the TU complex were examined. METHODS: The study was double-blind, randomized, placebo-controlled, two period cross-over in 16 healthy volunteers. During each period, subjects received 60 mg of terfenadine every 12 h on days 1 to 7 and 600 mg of either zileuton or placebo for zileuton every 6 h on days 1 to 10. Blood samples were obtained on days 7 to 10 and serial ECGs were performed on days -1 and 7 in both periods. RESULTS: The combination of zileuton and terfenadine was well tolerated. Coadministration of zileuton with terfenadine resulted in a significant increase in the mean AUC and Cmax of terfenadine by approximately 35% and the mean AUC and Cmax of carboxyterfenadine by approximately 15%. The maximum concentration of terfenadine observed in the study was 9.6 ng.ml-1. The addition of zileuton to terfenadine did not result in significant changes in the evaluated ECG-recordings (QTc interval and morphology of TU complex). The difference in means for both maximum and average QTc interval was very small (< or = 2.3 ms), and there were no clinically significant changes in individual values. CONCLUSIONS: The relatively small pharmacokinetic effect of zileuton on terfenadine metabolism, with no change in the QTc interval, is unlikely to be of clinical significance. The interaction is minimal in comparison to the background variability of the population.

Adult↗

Lack of pharmacokinetic interaction after administration of lansoprazole or omeprazole with prednisone.

In a recently reported case, administration of omeprazole, a "proton pump" inhibitor, was temporally associated with the clinical relapse of pemphigus in a 44-year-old woman whose condition had been stabilized with a fixed dose of prednisone, suggesting the possibility of a drug interaction. This placebo-controlled, randomized, double-blind, three-period crossover study was conducted to evaluate and compare the pharmacokinetics of prednisolone after a single dose of prednisone given during multi-dose administration of lansoprazole or omeprazole. Lansoprazole (30 mg), omeprazole (40 mg), or placebo was administered once daily under fasted conditions for 7 days to healthy male volunteers. On the seventh day, a single dose of prednisone (40 mg) was administered concomitantly with the study medication, and plasma prednisolone concentrations were measured by high-performance liquid chromatography for 24 hours thereafter. Two weeks separated the first doses of each study period. Eighteen volunteers entered the study; pharmacokinetic data were evaluable for 15 participants. Safety data were evaluable for 16 participants in the lansoprazole/prednisone group; 17 in the omeprazole/ prednisone group; and 17 in the placebo/prednisone group. The pharmacokinetic parameters for prednisolone, including the maximum observed plasma concentration (Cmax), time to maximum plasma concentration (tmax), terminal-phase half-life (t1/2), and area under the concentration-time curve, were comparable for the three regimens. Adverse events (AEs) rated as possibly or probably drug related were reported by 50%, 24%, and 47% for subjects in the lansoprazole, omeprazole, and placebo treatment groups, respectively. Headache was the most common drug-related AE. No serious AEs were reported, and no subject withdrew from the study because of an AE. Concomitant administration of lansoprazole or omeprazole does not affect the absorption, biotransformation, or disposition of a single dose of prednisone. All three treatment regimens were well tolerated.

2-Pyridinylmethylsulfinylbenzimidazoles↗

Pharmacokinetic interactions and side effects resulting from concomitant administration of lithium and divalproex sodium.

BACKGROUND: Valproic acid is added to the lithium regimens of many patients with bipolar disorder, especially those with mania refractory to lithium treatment. METHOD: We evaluated the pharmacokinetic effects and safety of coadministration of lithium and valproate in 16 healthy volunteers in this randomized, placebo-controlled, two-period (12 days each) crossover trial. Valproate or placebo was given twice daily. On Days 6-10, lithium was added. Blood samples drawn on Days 5 and 10 were analyzed for valproate by high-pressure liquid chromatography (HPLC) and for lithium by atomic absorption spectrophotometry. RESULTS: Lithium pharmacokinetics were unchanged by valproate, but valproate C(max), C(min), and AUC rose slightly during lithium coadministration. Adverse events did not change significantly. CONCLUSION: Concomitant administration of lithium and valproate appears to be safe in patients with bipolar disorder.

Adult↗

The effect of zileuton on antipyrine and indocyanine green disposition.

The effects of single and multiple oral doses of zileuton on the pharmacokinetics of antipyrine and indocyanine green were studied in 16 healthy, nonsmoking adult men by means of a double-blind, randomized, parallel placebo-controlled design. Indocyanine green disposition was not significantly altered by zileuton. Plasma antipyrine clearance declined by 20% (p < 0.0005) and 52% (p < 0.0005) after single and multiple dose zileuton exposure, respectively. Total urinary recovery of unchanged antipyrine and metabolites decreased with zileuton exposure. Selective declines from baseline of 16% (p = 0.007) and 20% (p = 0.003) after single-dose zileuton and 30% (p < 0.0005) and 43% (p < 0.0005) after multiple-dose zileuton were detected in recovery of 4-hydroxyantipyrine and 3-hydroxymethylantipyrine, respectively. Urinary recovery of the N-demethylantipyrine metabolite norantipyrine and percent of conjugation of 3-hydroxymethylantipyrine were unchanged by zileuton. In conclusion, zileuton therapy has no detectable effect on indocyanine green disposition but exerts marked effects on antipyrine plasma and urine metabolite disposition.

Administration, Oral↗

Pharmacokinetic interaction between lansoprazole and theophylline.

The pharmacokinetic interaction potential of the new proton-pump inhibitor lansoprazole and theophylline was assessed in a double-blind, two-period (13-day duration per period), multiple-dose crossover study in 14 healthy male volunteers. Lansoprazole 60 mg or placebo once daily was coadministered with anhydrous theophylline 200 mg four times daily. Plasma theophylline concentrations were quantitated via high-performance liquid chromatography. Lansoprazole did not appear to affect substantially the absorption profile or clearance of theophylline. Theophylline area under the plasma concentration-versus-time curve over the 6-h dosing interval decreased slightly (13%) but statistically significantly during lansoprazole coadministration. As the magnitude of this effect was small, this interaction is likely to be clinically insignificant.

2-Pyridinylmethylsulfinylbenzimidazoles↗

The pharmacokinetics of single oral doses of zileuton 200 to 800mg, its enantiomers, and its metabolites, in normal healthy volunteers.

The pharmacokinetics of single oral doses of zileuton 200 to 800mg, its R(+) and S(-) enantiomers, and its N-dehydroxylated and glucuronide metabolites have been investigated in a randomised study in 16 normal male healthy volunteers. Zileuton was 93.4% bound to plasma proteins. The overall dispositional pharmacokinetics of zileuton racemate appeared to be linear. The mean dose-normalised area under the concentration-time curve from zero to infinity (AUC0-infinity) remained constant, while the mean dose-normalised peak plasma concentration (Cmax) decreased with the increase in dose, possibly because of dissolution rate-limited absorption at the higher doses. The R(+) and S(-) enantiomers of zileuton may have similar absorption profiles, although the apparent total plasma clearance of the S(-) enantiomer was 49 to 76% higher than the corresponding values for the R(+) enantiomer. The AUC0-infinity of each enantiomer increased proportionately with dose. The pharmacokinetics of the N-dehydroxylated metabolite of zileuton were highly variable, with a more than dose-proportional increase in the mean dose-normalised Cmax and area under the concentration-time curve from zero to 24 hours. The elimination of the glucuronide metabolites of the R(+) and S(-) enantiomers of zileuton was formation rate-limited. The mean percentage of the administered zileuton dose recovered in urine as glucuronide metabolites ranged from 73.1 to 76.5% and showed no dose-related differences. The renal clearance of the glucuronide metabolites of zileuton exceeded the normal glomerular filtration rate, suggesting that these metabolites may be excreted through renal tubular secretion in addition to filtration.

Absorption↗

The effect of mild or moderate hepatic impairment (cirrhosis) on the pharmacokinetics of zileuton.

The pharmacokinetics of zileuton and its R(+) and S(-) glucuronide metabolites were determined after single and multiple (400mg every 8 hours) oral dose administration in healthy subjects (n = 5) and patients with mild or moderate hepatic impairment (cirrhosis; n = 8). The clearance of total zileuton (unbound plus bound to plasma proteins) in patients with hepatic impairment (approximately 350 ml/min) was approximately half than in healthy subjects (approximately 670 ml/min), with similar values in patients with mild or moderate cirrhosis. However, the clearance of unbound zileuton in patients with moderate hepatic impairment was nearly half that in patients with mild hepatic impairment, and one quarter that in healthy subjects. On the basis of these findings, it may be necessary to reduce the dose in patients with impaired hepatic function to maintain levels similar to those in healthy subjects.

Administration, Oral↗

The effect of food on the pharmacokinetics of zileuton.

The present study was undertaken to assess the effect of food on the pharmacokinetic parameters of zileuton. In a nonblinded crossover study, 18 healthy male volunteers who had fasted overnight were randomised to receive a single oral dose of zileuton 600mg in the presence or absence of food consisting of a standardised breakfast on the following morning. The mean zileuton peak plasma concentration (Cmax) increased significantly by 27% after food intake, while the mean area under the plasma concentration versus time curve increased by only 1.4%, a difference that was not statistically significant. The mean time to Cmax was unaffected by the presence of food, as were the other pharmacokinetic parameters assessed. Overall, the results suggest that food has a relatively small effect on the rate of zileuton absorption compared with the fasting state, while the bioavailability of the drug appears to be unaffected. Thus, it is concluded that it is appropriate to administer zileuton with or without food.

Absorption↗

Pharmacodynamic and stereoselective pharmacokinetic interactions between zileuton and warfarin in humans.

A double-blind parallel randomised study was conducted to assess the effects of multiple oral doses of zileuton (600mg every 6 hours) or matching placebo on the steady-state pharmacokinetics and pharmacodynamics of warfarin titrated to a prothrombin time of 14 to 18 seconds in 24 healthy adult male volunteers. Serial blood samples were collected for assessment of prothrombin times and R- and S-warfarin plasma concentrations. Coadministration of zileuton and warfarin had no effect on S-warfarin pharmacokinetics but statistically significantly increased mean R-warfarin plasma concentrations and decreased mean R-warfarin total oral plasma clearance compared with warfarin alone (by 15%). This stereoselective interaction was accompanied by an increase in mean morning (predose) and evening (12-hour postdose) prothrombin times from 17.5 to 19.8 seconds and 17.1 to 19.1 seconds, respectively; the corresponding changes in the placebo group were from 18.1 to 18.8 seconds and 17.3 to 17.5 seconds. Thus, multiple dose administration of zileuton appears to significantly alter steady-state R-warfarin pharmacokinetics and pharmacodynamics. Careful monitoring of prothrombin times with appropriate dose titration of warfarin is recommended with concurrent therapy of zileuton and warfarin.

Administration, Oral↗

Effect of zileuton on theophylline pharmacokinetics.

In controlled trials involving asthma patients, zileuton - a selective 5-lipoxygenase inhibitor - has significantly improved pulmonary function and reduced symptoms. Since theophylline is frequently prescribed for asthma, we designed a placebo-controlled randomised crossover trial to examine the influence of zileuton on theophylline pharmacokinetics. 16 healthy adult males were given theophylline (Slo-Phyllin) 200mg 4 times daily for 5 days and either zileuton 800mg twice daily or a matching placebo. After a 15-day washout period, theophylline was resumed and the other study drugs reversed. During coadministration with zileuton, mean peak theophylline levels rose from 12.14 to 20.99 mg/L (p < 0.001), while the apparent plasma clearance dropped from 3.74 to 1.91 L/h (p < 0.001). The time to the peak theophylline concentration was delayed by 0.5 hours and the half-life was significantly prolonged by 1.5 hours. 14 volunteers reported 44 mild or moderately severe adverse events, possibly or probably related to coadministration of zileuton, and 8 volunteers reported 8 such events with placebo coadministration. Three volunteers receiving theophylline plus zileuton withdrew from the trial prematurely. Thus, a pharmacokinetic interaction that may produce theophylline toxicity exists between zileuton and theophylline. Accordingly, theophylline dosages in patients receiving zileuton should be adjusted to maintain levels within the therapeutic range. Upon initiation of zileuton, the typical asthma patient may require dosage reductions of one-half, and monitoring of plasma theophylline concentrations is recommended.

Administration, Oral↗