Lack of pharmacokinetic drug-drug interaction between ciclesonide and erythromycin.

OBJECTIVE: To investigate whether systemic exposure to desisobutyrylciclesonide (des-CIC) (the pharmacologically active metabolite of ciclesonide) and erythromycin are affected by combined administration of ciclesonide and erythromycin. METHODS: 18 healthy subjects were enrolled in a Phase 1, open-label, randomized, three-period crossover study. Each subject received ciclesonide (640 microg ex-actuator, equivalent to 800 microg ex-valve, via hydrofluoroalkane metered-dose inhaler) and erythromycin (500 mg PO), separately and in combination, in random order. Blood samples were collected at timed intervals to determine serum concentrations of erythromycin, des-CIC, and ciclesonide using HPLC-MS detection. Adverse events were recorded throughout the study. RESULTS: Combined administration of ciclesonide and erythromycin did not alter the pharmacokinetics (PK) of either drug. The serum concentration vs. time profiles of erythromycin, des-CIC, and ciclesonide were similar when ciclesonide and erythromycin were administered separately or together. In addition, the PK characteristics of erythromycin and des-CIC were equivalent following single or co-administration. Point estimates (90% confidence intervals (CI)) for erythromycin were as follows: AUC0-inf, 0.96 (0.79, 1.18); Cmax, 1.00 (0.84, 1.20); and t1/2, 0.96 (0.83, 1.12). The following point estimates (90% CI) were obtained for des-CIC: AUC0-inf, 1.16 (1.03, 1.30); Cmax, 1.06 (0.98, 1.15); and t1/2, 1.04 (0.96, 1.13). Lack of ciclesonide/erythromycin interaction was demonstrated as the 90% CI of AUC0-inf, Cmax, and t1/2 of both compounds were entirely within the stipulated equivalence range of 0.67 - 1.50. No study drug-related adverse events occurred during this study. CONCLUSIONS: Combined administration of ciclesonide and erythromycin did not alter the PK properties of either drug. Both drugs were safe and well-tolerated. Therefore, systemic exposure to ciclesonide or erythromycin is not increased in patients receiving concomitant therapy.

Equivalence concepts in clinical trials.

According to the recent ICH E9 Guidance Statistical Principles for Clinical Trials, efficacy is most convincingly established by demonstrating superiority to placebo, by showing superiority to an active control treatment or by demonstrating a dose-response relationship (so-called 'superiority' trials). For serious illnesses, a placebo-controlled trial may be considered unethical if a therapeutic treatment exists which has proven efficacious in relevant superiority trial(s). In that case, the scientifically sound use of an active treatment as a control should be considered. Active control trials designed to show that the efficacy of an investigational product is not relevantly worse than that of the active comparator are called 'non-inferiority' trials (1). After having confirmed non-inferiority, superiority of the alternative test treatment over the reference treatment can additionally be tested without the need to adjust the significance level (2). In contrast to cross-over bioequivalence trials based on pharmacokinetic endpoints such as AUC and Cmax, therapeutic equivalence and non-inferiority trials are based on clinical end-points. Therefore, they are often conducted as parallel group comparisons. It is important to note that the conclusion of equivalence or non-inferiority is based on the inclusion of the appropriate confidence interval in the equivalence acceptance range, and that it cannot be derived from a non-significant test result of the inappropriate null hypothesis of no treatment difference.

The U.S. draft guidance regarding population and individual bioequivalence approaches: comments by a research-based pharmaceutical company.

Generally, the motivation for switching from average bioequivalence to population and/or individual bio-equivalence is well recognized in the light of certain limitations of the concept of average bioequivalence. However, this switch still results in unresolved issues which should be addressed before the regulatory guidance is finalized.

A dose-dependent effect of the novel inhaled corticosteroid ciclesonide on airway responsiveness to adenosine-5'-monophosphate in asthmatic patients.

Inhaled corticosteroids decrease airway responsiveness in asthma partly through suppression of airway inflammation. We have previously demonstrated that inhaled budesonide reduced airway responsiveness to the mast cell stimulus adenosine-5'-monophosphate (AMP) to a threefold greater extent than to methacholine and sodium metabisulfite, suggesting that AMP responsiveness may be a more sensitive marker of airway inflammation and steroid action in order to assess a dose-response relationship. To investigate this, we studied the effects of three doses of the novel corticosteroid ciclesonide (50 micrograms, 200 micrograms, and 800 micrograms) inhaled as a dry powder twice daily on airway responsiveness to AMP and inflammatory parameters in induced sputum. In a three-parallel-dose group, double-blind, placebo-controlled, randomized, crossover study, with a washout period of 3 to 8 wk, a total of 29 patients with mild to moderate allergic asthma underwent AMP challenge and sputum induction before and after 14 d of treatment with ciclesonide or matched placebo. Compared with placebo, ciclesonide 100 micrograms, 400 micrograms, and 1,600 micrograms daily reduced airway responsiveness to AMP by 1.6 (95% confidence interval [CI], -0.1 to 3.4, not significant [NS]), 2.0 (95% CI, 0.4 to 3.6, p < 0.05), and 3.4 (95% CI, 2.3 to 4. 4, p < 0.05) doubling doses, respectively, and this reduction in airway responsiveness was dose-dependent (p = 0.039). A significant reduction in the percentage of eosinophils in induced sputum was observed after 400 micrograms and 1,600 micrograms daily ciclesonide (p < 0. 05), but this was not dose-dependent. Sputum eosinophil cationic protein (ECP) was significantly reduced after 400 micrograms daily ciclesonide only (p < 0.05). Thus, in patients with mild to moderate asthma, assessment of airway responsiveness to AMP, rather than inflammatory parameters in induced sputum, represents a sensitive method to evaluate a dose-response relationship of an inhaled corticosteroid and may have applications in evaluating other novel inhaled corticosteroids.

Pantoprazole lacks induction of CYP1A2 activity in man.

OBJECTIVE: This drug-drug interaction study investigated the potential influence of the proton pump inhibitor pantoprazole on the CYP1A2 activity as assessed by urinary excretion of caffeine metabolites. SUBJECTS, MATERIALS AND METHODS: 12 healthy, non-smoking volunteers underwent two treatment periods of 7 days each in randomized order with once-daily oral intake of 40 mg pantoprazole (test) or placebo (reference). On days 6 and 7 of both periods, 200 mg caffeine was administered two hours after pantoprazole intake, i.e. at the expected t(max) of pantoprazole serum concentrations. Urinary excretion of the caffeine metabolites 1X, 1U, AFMU, 17U was measured up to 8 hours after caffeine intake. In accordance with recent guidelines on drug-drug interactions, lack of interaction was handled as an equivalence problem. RESULTS: Point estimate and 90% confidence intervals (CI) of the respective ratios test/reference were 0.91 (0.81, 1.03) for (1X + 1U + AFMU)/17U, indicative for CYP1A2 activity, 1.03 (0.94, 1.13) for AFMU/1X (N-acetyl transferase activity) and 1.01 (0.94, 1.09) for 1U/1X (xanthine oxidase activity). CONCLUSION: Pantoprazole does not induce CYP1A2 activity, consistent with previous findings following theophylline administration, nor does it have any influence on N-acetyl-transferase or xanthine oxidase activity.

Pantoprazole does not interact with the pharmacokinetics of carbamazepine.

OBJECTIVE: Pantoprazole is a H+/K+-ATPase inhibitor with a minimized potential of interaction with the cytochrome P450 system. Imidazole derivatives such as cimetidine and omeprazole have been shown to markedly interact with carbamazepine, a major anticonvulsant with a narrow therapeutic range. Therefore, the influence of steady-state pantoprazole on the pharmacokinetics of carbamazepine was investigated. SUBJECTS AND METHODS: N = 20 healthy volunteers (12 male/8 female) completed a double-blind, placebo-controlled, randomized crossover study. During the test period they received 40 mg pantoprazole p.o. once daily for 11 days and concomitantly a single oral dose of 400 mg carbamazepine on day 5. In the reference period placebo was administered instead of pantoprazole. RESULTS: Serum concentrations of carbamazepine and its active metabolite carbamazepine-10,11-epoxide were measured until day 11. Geometric means of AUC (extent characteristic) and Cmax/AUC (rate characteristic) of carbamazepine were 292 and 287 mgxh/l, and 0.0150 and 0.0144 l/h (reference and test), respectively. Point estimates and 90% confidence intervals of the ratios were 0.98 (0.95, 1.01) for AUC, and 0.96 (0.92, 1.00) for Cmax/AUC, respectively. Since the 90% confidence intervals of the primary characteristics, AUC and Cmax/AUC were entirely within the predefined equivalence range of 0.80 - 1.25, lack of interaction of pantoprazole with the pharmacokinetics of carbamazepine was demonstrated. Equivalence was also demonstrated for carbamazepine-10,11-epoxide using the characteristics AUC and Cmax. CONCLUSION: No dose adjustment of carbamazepine is therefore required during concomitant treatment with pantoprazole.

[Comparison of addition of theophylline to inhaled steroid with doubling of the dose of inhaled steroid in asthma]. / Zusätzliche Gabe von Theophyllin bei einer Therapie mit inhalativen Steroiden im Vergleich zu einer Verdoppelung der Dosis inhalativer Steroide bei Asthma.

The anti-asthmatic effect of theophylline may supplement those of inhaled steroids in asthma. The aim of the present trial was to study how the addition of theophylline compares to doubling the dose of inhaled steroid in asthmatics who remain symptomatic on beclomethasone dipropionate (BDP) 400 micrograms/day. The trial was designed as a randomized, double-blind, parallel-group study in several European countries. 69 patients were treated for 6 weeks with theophylline plus BDP 400 micrograms/day, compared to 64 patients treated with BDP 800 micrograms/day. The mean +/- SD serum theophylline concentration was 10.1 +/- 4.2 mg/l. Lung function measurements were made throughout the study and patients kept daily records of peak expiratory flow rate (PEF), symptoms and salbutamol usage. Forced expiratory volume in one second and PEF at week 6 were significantly increased by both treatments (p < 0.01). PEF variability was reduced by about 30% in both groups. There were significant improvements in asthma symptoms and rescue medication use (p < 0.001). There were no significant differences between the treatment groups. The study demonstrated clinical equivalence of theophylline plus beclomethasone dipropionate 400 micrograms/day and beclomethasone dipropionate 800 micrograms/day in patients whose asthma is not controlled on beclomethasone dipropionate 400 micrograms/d. The results support the use of theophylline as steroid-sparing agent. The combination of low-dose inhaled steroid plus theophylline is a suitable treatment for moderate asthma.

Asthma management: the challenge of equivalence.

Increasing prevalence and severity of asthma worldwide encourage the development of new antiasthmatic drugs, alternative treatment regimens and improved formulations of established drugs. Whereas the efficacy of new chemical entities (NCEs) is usually demonstrated by superiority over placebo or a subtherapeutic dose of the active drug, equivalence concepts have to be used in the following situations: the need to replace chlorofluorocarbon (CFC) propellants for inhalative asthma medications by suitable alternatives, and the need to demonstrate that an alternative treatment regimen is not clinically inferior to an established reference treatment. To cover both situations, the recent ICH guidance on biostatistics clearly distinguishes between two-sided equivalence trials and one-sided non-inferiority trials. In this context, non-inferiority always means "not inferior by a clinically relevant amount". After having confirmed non-inferiority, superiority of the alternative test treatment over the reference treatment can additionally be tested without the need to adjust the significance level. The definition of equivalence acceptance limits becomes crucial, particularly in studies conducted in the flat range of the dose-response curve of inhaled steroids. In order to assess the non-inferiority of steroid sparing add-on treatments we propose a one-sided test based on post-/pre-ratios which have substantially reduced coefficients of variation compared to the post-treatment values themselves. The non-inferiority acceptance limit of 0.90 - as opposed to 0.80 in bioequivalence assessment - reflects clinically irrelevant changes of lung function variables. The proposed methodology is illustrated by 2 examples from randomized, double-blind, parallel-group studies comparing inhaled steroid plus theophylline versus doubling the steroid dose in asthmatics who are symptomatic on low-dose inhaled steroid.

Relative bioavailability of rapidly dispersing, plain, and microencapsuled acetylsalicylic acid tablets after single dose administration.

UNLABELLED: Extent and rate of absorption of acetylsalicylic acid (ASA) from rapidly dispersing (Acesal Extra) and plain tablets (Acesal) relative to reference 1 (plain tablets, Aspirin) and from microcapsuled tablets (Micristin) relative to comparable listed tablets (reference 2, Colfarit) were assessed in 2 single-dose (0.5 g ASA), open, randomized, crossover studies with intervals of 14 days between 2 periods. Both studies were performed in 24 male and female healthy volunteers each (age 18-32 years, body weight 48-90 kg, body height 161-190 cm). ASA and its metabolite salicylic acid (SA) were measured with an HPLC method validated for ASA between 0.2 and 20 microg/ml and for SA between 0.4 and 40 microg/ml. The test tablets were considered bioequivalent with reference in extent of absorption if the 90% confidence limits of the AUC0 to infinity ratio were within the range of 0.80-1.25, and in rate of absorption if the confidence limits of the Cmax/AUC0 to infinity ratios were within 0.70-1.43. RESULTS: Geometric means and 90% confidence limits for the test/reference ratios of the comparisons Acesal vs reference 1, Acesal Extra vs reference 1 and Micristin vs reference 2 were 1.05 (0.97-1.13), 1.13 (1.05-1.22), 1.02 (0.92-1.14) for ASA AUC0 to infinity and 1.02 (0.96-1.07), 1.05 (0.99-1.11), 0.98 (0.91-1.04) for SA AUC0 to infinity, respectively. The results for Cmax/AUC of ASA were 1.16 (1.00-1.34), 1.72 (1.49-1.99), 0.83 (0.73-0.94) and of SA 1.02 (0.98-1.07), 1.07 (1.02-1.12), 0.93 (0.88-0.97). CONCLUSION: Acesal and Micristin were bioequivalent with the respective references in both extent and rate of absorption. Acesal Extra and reference 1 were bioequivalent with regard to extent only. Acesal Extra was absorbed faster.

Differences in pH-dependent activation rates of substituted benzimidazoles and biological in vitro correlates.

Gastric proton pump inhibitors (PPIs) are substituted benzimidazole prodrugs that require an acid-induced activation. Its rate depends on the reactivity of the molecule relative to the environmental pH and determines the drug's tissue selectivity. Factors affecting the exposure of moderately acidic tissues to the activated PPI are the area under the serum concentration-time curve (AUC), serum protein binding, the partition coefficient logP and the serum elimination half-life relative to the chemical activation half-life at a critical tissue pH of about 5. These parameters have therefore been determined in a comparative fashion in the present study. The data shows that pantoprazole is less likely to undergo unwanted activation at moderately acidic targets as opposed to the parietal cell, compared to omeprazole. Actually, although 40 mg pantoprazole (steady state) gave a slightly higher serum AUC of the total parent compound than 40 mg omeprazole (10.5 vs. 7.1 micromol x h x l[-1]), a higher serum protein binding of pantoprazole versus omeprazole (98 vs. 96%) reversed the AUC values for the free drug in favor of a lower value for pantoprazole (0.19 vs. 0.28 micromol x h x l[-1]). It is the free parent compound that equilibrates across cell membranes to be activated in acidic tissue compartments. At pH 5.1, the activation half-life of pantoprazole was 4.7 versus 1.4 h for omeprazole, the latter being in the order of the common serum elimination half-life determined in an intraindividual comparison (1.24 vs. 1.25 h). Thus, pantoprazole is eliminated faster from blood than it is activated at a pH of about 5, while omeprazole is as quickly activated at this pH as it is eliminated from blood. Biological in vitro experiments confirmed that pantoprazole displays a lower liability to interfere with unwanted biological targets. This has been demonstrated in vitro for inhibition of both renal Na+/K+-ATPase, lysosomal acidification and the production of reactive oxygen species by neutrophils.

Interobserver agreement: Cohen's kappa coefficient does not necessarily reflect the percentage of patients with congruent classifications.

A widely accepted approach to evaluate interrater reliability for categorical responses involves the rating of n subjects by at least 2 raters. Frequently, there are only 2 response categories, such as positive or negative diagnosis. The same approach is commonly used to assess the concordant classification by 2 diagnostic methods. Depending on whether one uses the percent agreement as such or corrected for that expected by chance, i.e. Cohen's kappa coefficient, one can get quite different values. This short communication demonstrates that Cohen's kappa coefficient of agreement between 2 raters or 2 diagnostic methods based on binary (yes/no) responses does not parallel the percentage of patients with congruent classifications. Therefore, it may be of limited value in the assessment of increases in the interrater reliability due to an improved diagnostic method. The percentage of patients with congruent classifications is of easier clinical interpretation, however, does not account for the percent of agreement expected by chance. We, therefore, recommend to present both, the percentage of patients with congruent classifications, and Cohen's kappa coefficient with 95% confidence limits.

Individual bioequivalence--a European perspective.

Regulatory requirements for average bioequivalence have been internationally harmonized, which is by no means the case for the more recent concept of individual bioequivalence. The main reason for introducing more complex replicate designs and bioequivalence criteria are the highly variable drugs, for which the setting of suitable bioequivalence ranges poses a major problem and scaling of the bioequivalence criteria by the intrasubject variability has been suggested. The shortcoming of the present two-treatment, two-period (2 x 2) crossover design to detect subject-by-formulation interaction provides a second argument in favor of the more complex replicate designs. A unified approach of proposed statistical procedures for the replicate design has been given by Schall. However, the availability of these methods and understanding of them seems to be limited to a small working group, so a broader international awareness of the problems and potentional solutions is desirable.

Choice of student's t- or Wilcoxon-based confidence intervals for assessment of average bioequivalence.

An open question in the analysis of average bioequivalence is whether the nonparametric (Wilcoxon) or parametric (t) approaches to two one-sided tests is preferable. Previous work has made particular distributional assumptions as to the distribution of AUC and C(max). Instead, we simulate data according to a pharmacokinetic model for an immediate-release formulation. We find that both approaches have estimated level consistent with the nominal 5%. The only concern is a possible anticonservativeness of the parametric approach for C(max). Further, the nonparametric approach is consistently less powerful than the parametric for the cases studied.

Comparison of addition of theophylline to inhaled steroid with doubling of the dose of inhaled steroid in asthma.

The anti-asthmatic effects of theophylline may supplement those of inhaled steroids in asthma. The aim of the present trial was to study how the addition of theophylline compares to doubling the dose of inhaled steroid in asthmatics who remain symptomatic on beclomethasone dipropionate (BDP) 400 microg x day(-1). The trial was designed as a randomized, double-blind, parallel-group study in several European countries. Sixty nine patients were treated for 6 weeks with theophylline plus BDP 400 microg x day(-1), compared to 64 patients treated with BDP 800 micro x day(-1). The mean+/-SD serum theophylline concentration was 10.1+/-4.2 mg x L(-1). Lung function measurements were made throughout the study and patients kept daily records of peak expiratory flow (PEF), symptoms and salbutamol usage. Forced expiratory volume in one second and PEF at week 6 were significantly increased by both treatments (p<0.01). PEF variability was reduced by about 30% in both groups. There were significant improvements in asthma symptoms and rescue medication use (p<0.001). There were no significant differences between the treatment groups. The study demonstrated clinical equivalence of theophylline plus beclomethasone dipropionate 400 microg x day(-1) and beclomethasone dipropionate 800 microg x day(-1) in patients whose asthma is not controlled on beclomethasone dipropionate 400 microg x day(-1). The results support the use of theophylline as a steroid-sparing agent. The combination of low-dose inhaled steroid plus theophylline is a suitable treatment for moderate asthma.

Pantoprazole has no influence on steady state pharmacokinetics and pharmacodynamics of metoprolol in healthy volunteers.

The new H+/K+ ATPase inhibitor pantoprazole, a substituted benzimidazole, is metabolized by the hepatic cytochrome P450 enzymes 2C19 or 3A4 and subsequently undergoes phase II metabolism. The widely used beta 1-adrenoreceptor-blocking agent metoprolol is metabolized via CYP2D6. The influence of pantoprazole on the pharmacokinetics of an orally administered zero order kinetics formulation (ZOK) of metoprolol was the objective of this study. Eighteen volunteers (9 female, 9 male, age 20-44 years) completed the randomized, double-blind crossover study. Each subject received either 95 mg metoprolol and placebo (reference (R)) or 95 mg metoprolol and 40 mg pantoprazole (test (T)) as oral doses (sid) for 5 consecutive days. On day 5 of each period serum concentrations of R- and S-metoprolol were determined and a treadmill ergometry was performed. The primary pharmacokinetic characteristics for extent and rate of absorption were AUC(0-24h) and % PTF, respectively. To assess the pharmacodynamic effect of metoprolol the excess area under the effect vs. time curve was calculated for heart rate during ergometry (AUCexHR). Point estimate and 90% confidence limits (CI) for the ratios of population medians of T and R were given. The respective point estimates (90% CI) of the ratios of both primary and secondary characteristics were entirely within the equivalence range of 0.80 and 1.25 for both enantiomers of metoprolol. Moreover, equivalence could be shown for the pharmacodynamic characteristic AUCexHR. Hence, it was concluded that pantoprazole does not interact with metoprolol pharmacokinetics or pharmacodynamics. Therefore, no dose adjustment of metoprolol during therapy with pantoprazole is necessary.

Controlled-release theophylline inhibits early morning airway obstruction and hyperresponsiveness in asthmatic subjects.

BACKGROUND: Nocturnal asthma reflects the severity of the disease, and thus its pharmacologic prevention represents one on the main goals of asthma management. SUBJECTS AND METHODS: To determine whether controlled-release theophylline inhibits the development of airway obstruction and/or airway hyperresponsiveness early in the morning, we examined 18 subjects reporting recurrent nocturnal asthma. In each subject, after five days' treatment with an 8 PM increasing dose of oral controlled-release theophylline, up to 10 +/- 1 mg/kg or placebo the night before the study day, we measured serum theophylline, FEV1 and PC20FEV1 at 6 AM, 2 PM and 10 PM. RESULTS: At 6 AM, both FEV1 and PC20FEV1 were significantly higher on theophylline than on placebo (3.52 +/- 0.22 versus 3.17 +/- 0.25 L; P < .005 and 2.76 divided by 3.61 versus 1.55 divided by 3.73 mg/mL; P < .05, respectively). At 2 PM and 10 PM FEV1, but not PC20FEV1, was higher on theophylline than on placebo (3.73 +/- 0.21 versus 3.54 +/- 0.25 L; P < .05 and 3.40 +/- 0.22 versus 3.24 +/- 0.24 L; P < .05). Serum theophylline was 12.8 +/- 1.1 micrograms/ml, 8.9 +/- 0.77 and 9.5 +/- 0.85 at 6 AM, 2 PM and 10 PM, respectively. CONCLUSIONS: We conclude that an evening dose of controlled-release theophyl line inhibits early morning airway obstruction and hyperresponsiveness, and that it may be helpful in the prevention of nocturnal asthma.

Lack of pharmacokinetic interaction of pantoprazole with diazepam in man.

Pantoprazole, a substituted benzimidazole, is a potent and well tolerated inhibitor of the gastric H+,K(+)-ATPase with a low potential to inhibit cytochrome P450. In this randomized, placebo-controlled two-period crossover study, 12 healthy volunteers received placebo (reference) and 240 mg of pantoprazole (test) i.v. within 2 min once daily for 7 days each. On day 4 of either period, a 1 min bolus of diazepam (0.1 mg kg-1 body weight) was additionally injected. Pantoprazole was well tolerated and did not cause clinically relevant changes in heart rate, blood pressure, ECG and routine clinical laboratory parameters. There was no effect on diazepam clearance (0.021 1 h-1 kg-1 for test and reference) and elimination half-life (36.8 for test, 40.4 h for reference). Diazepam metabolism to desmethyldiazepam was not affected by pantoprazole. In conclusion, pantoprazole and diazepam may be administered concomitantly without dose adjustment even when high doses of pantoprazole are required.

Lack of pantoprazole drug interactions in man: an updated review.

This review summarizes the results of pharmacokinetic and pharmacodynamic drug interaction studies in man with pantoprazole, a new, selective proton pump inhibitor. Various mechanisms have to be considered as causes for potential drug-drug interactions. Proton pump inhibitors (PPIs) in general may alter the absorption of drugs by increasing the intragastric pH. Due to the presence of an imidazole ring, the PPIs of the class of substituted benzimidazole sulfoxides may interfere with the metabolism of other drugs by altering the activity of drug metabolizing enzymes of the cytochrome P450 system, via either induction or inhibition. With the increasing use of PPIs, their interaction potential gains therapeutic importance as was the case with the first and second generation of H2-blockers (cimetidine and ranitidine, respectively). The enhanced selectivity of pantoprazole to the gastric H+/K(+)-ATPase characterizes the new PPI generation. In contrast to omeprazole, pantoprazole has a low potential to interact with the cytochrome P450 system in man. In the drug interaction studies conducted so far, substrates for all relevant cytochrome P450 families involved in the metabolism of drugs in man were investigated. Pantoprazole did not affect the pharmacokinetics or pharmacodynamics of antipyrine, caffeine, carbamazepine, diazepam, diclofenac, digoxin, ethanol, glibenclamide, a hormonal contraceptive (combination of levonorgestrel and ethinylestradiol), metoprolol, nifedipine, phenprocoumon, phenytoin, theophylline and warfarin in man. Pantoprazole also neither induced the metabolism of antipyrine or caffeine, nor increased urinary excretion of the induction markers D-glucaric acid and 6 beta-hydroxycortisol. Vice versa, the investigated drugs had no relevant influence on the pharmacokinetics of pantoprazole.

Pharmacokinetics and drug interactions--relevant factors for the choice of a drug.

Pharmacokinetics serve as a useful tool in drug development by identifying the drug's disposition and elimination characteristics, the absorption characteristics of the biopharmaceutical formulation, and the therapeutic dose regimen in various patient populations. Where two or more drugs of a class have a similar efficacy, the choice of the drug may depend upon the reproducibility of the pharmacokinetics and the minimal risk of drug interaction. Pantoprazole, a selective proton pump inhibitor, appears to meet the above criteria. As opposed to other members of the class, pantoprazole exhibits linear, predictable pharmacokinetics and lack of drug interactions.