Intravaginal Tolterodine Formulation Intended for Overactive Bladder Treatment-Results of a Pharmacokinetic Phase I Pilot Study in Healthy, Postmenopausal Women.

The aim was to assess the pharmacokinetics of tolterodine released from vaginal rings and of its active metabolite 5-hydroxymethyl tolterodine (5-HMT) compared to the respective pharmacokinetics resulting from oral administration of extended-release tolterodine in healthy, postmenopausal women. In this single-center, open-label trial, subjects received 4 treatments in a fixed sequence: fasted oral extended-release tolterodine 2.74 mg/d (reference, 5 days), single vaginal rings; tolterodine releasing rates: 0.95 mg/d (test 1, 13 days), 1.40 mg/d (test 2, 28 days), 1.90 mg/d (test 3, 28 days). Systemic exposure of tolterodine, 5-HMT, and the molar sum of unbound tolterodine/5-HMT (active moiety [AM]) in steady state was determined. Sixteen of 18 included women completed the study. For the oral formulation, peak-trough fluctuations of tolterodine, 5-HMT, and AM plasma concentrations (AM: mean maximum/minimum concentration, 2580/574 pmol/L = 4.5) were large. Intravaginal application led to steadier plasma concentrations (AM, test 3: mean maximum/minimum concentration, 1880/814 pmol/L = 2.3; fluctuation due to initial peak), which is the result of constant releasing rates after ring insertion over the 28-day application period. The vaginal rings demonstrated a favorable local tolerability. The most common adverse events with oral and vaginal tolterodine were headache (n = 11) and dry mouth (n = 8). Vaginal rings releasing tolterodine represent a promising new formulation for overactive bladder treatment with little fluctuation of drug plasma levels. This is expected to lead to a more predictable and continuous therapeutic effect and a reduced frequency of side effects compared to oral tolterodine.

Pharmacokinetics of oral pridinol: Results of a randomized, crossover bioequivalence trial in healthy subjects.

OBJECTIVES: To establish the relative bioavailability and to assess bioequivalence of oral, immediate-release tablets containing pridinol and to determine the pharmacokinetic properties of the compound. METHODS AND MATERIALS: In this single-center, open-label, randomized, crossover trial, healthy male and female adult subjects received single doses of the test and reference product containing 4 mg pridinol mesylate (equivalent to 3 mg pridinol) each under fasting conditions. For pharmacokinetic evaluation, blood samples were withdrawn until 72 hours post dose. Pridinol in plasma was quantified by validated liquid chromatography-mass spectrometry/mass spectrometry (LC-MS/MS). Adverse events (AEs) were analyzed descriptively. RESULTS: Of 34 randomized subjects, 33 completed all treatments. The determined pharmacokinetic parameters were quite similar for both products, with geometric means for maximum exposure (Cmax) of 29.27 ng/mL (test) and 27.44 ng/mL (reference), reached after 1.00 and 0.90 hours (mean tmax), respectively. The extents of bioavailability (geometric mean AUC0-tlast) were 187.93 h×ng/mL (test) and 183.51 h×ng/mL (reference). Elimination half-lives (T1/2) ranged from 8.97 to 34.85 hours with comparable mean T1/2 of 19.14 hours (test) and 18.85 hours (reference). The point estimates of the test/reference-adjusted geometric mean ratios of AUC0-tlast, Cmax (primary), and AUC0-∞ (secondary) were 102.54% (90% confidence interval: 96.19 - 109.32%), 106.79% (99.00 - 115.20%), and 102.60% (96.20 - 109.43%), respectively. Overall, 23 subjects experienced 50 AEs; headache and dizziness (15 cases each) were most frequently reported. CONCLUSION: Bioequivalence of both pridinol products was demonstrated in terms of rate and extent of absorption. Safety and tolerability were in accordance with the known AE profile of the drug substance.

Single-dose pharmacokinetics and pharmacodynamics assessment of oestriol and trimegestone containing vaginal rings in healthy women with childbearing potential.

PURPOSE: To evaluate the pharmacokinetics and pharmacodynamics of oestriol (E3) and trimegestone (TMG) in healthy women after application of three different vaginal rings over 21 days. The vaginal rings had a nominal delivery rate of 0.413/0.050 mg/day (Test 1), 0.311/0.090 mg/day (Test 2) and 0.209/0.137 mg/day (Test 3) E3/TMG. METHODS: Thirty-five healthy women were randomised to receive a single application of Test 1, 2 or 3 (Clinical Trial NCT03343912). The E3 and TMG plasma concentration was determined by LC-MS/MS. Oestradiol (E2) and progesterone (PG) serum concentrations, and bleeding patern were determined as pharmacodynamic parameters. Safety was assessed by evaluation of adverse events and local tolerability. RESULTS: The total and maximum exposure of E3 and TMG increased in a proportional ratio to dose. However, not in a magnitude which was expected from the dose differences for E3. During Test 2 and 3 treatment all E2 and PG values remained on a well suppressed level until end of treatment. E2 and PG serum levels increased distinctly earlier after ring removal with Test 1 compared to Test 2 and 3. Test 3 achieved 95.24% of "no bleeding" days under treatment followed by Test 1 (91.67%), and Test 2 (86.15%). CONCLUSIONS: The Test 3 formulation presented the best dose combination of E3/TMG for contraception. Moreover, all vaginal rings were well tolerated.

Investigations on dose proportionality and drug-drug interaction for a fixed-dose combination of trazodone and gabapentin.

OBJECTIVES: To establish dose proportionality for trazodone and gabapentin at fixed ratios of trazodone/gabapentin 2.5/25, 10/100, and 30/300 and investigation of potential drug-drug interaction at a dose of 10/100. MATERIALS AND METHODS: 29 out of 30 healthy subjects completed this single-center, open-label, randomized, 5-period cross-over trial with single-dose fasted administrations. Administrations were separated by a washout period of at least 6 days. Blood samples were drawn until 48 hours post dose. A validated liquid chromatography-tandem mass spectrometry method (LC-MS/MS) was applied for determination of trazodone and gabapentin in plasma. The lower limits of quantitation (LLOQ) were 1.00 ng/mL and 5.00 ng/mL for trazodone and gabapentin, respectively. Adverse events (AEs) were analyzed in the study population descriptively. RESULTS: Plasma concentrations were characterized thoroughly. For trazodone, assessment of proportionality (power model/pairwise-comparison by ANOVA) showed proportionality for AUC over all doses and for Cmax between the middle and high dose. For gabapentin, a less than proportional increase in both metrices was present with a likely proportional increase from 25 to 100 mg only. Considering common bioequivalence criteria, absence of pharmacokinetic interaction was confirmed comparing the combination and individual agents. 23 subjects experienced 53 AEs during the trial, the most frequent being fatigue (20 cases/15 subjects) and dizziness (14 cases/11 subjects). No serious AEs were reported. CONCLUSION: To our knowledge, for the first time, proportionality for trazodone at doses of 2.5 to 30 mg and for gabapentin at doses of 25 to 300 mg was investigated. Absence of a pharmacokinetic interaction was shown.

Biomarkers and coagulation tests for assessing the biosimilarity of a generic low-molecular-weight heparin: results of a study in healthy subjects with enoxaparin.

Low-molecular-weight heparins (LMWHs) differ considerably in their influence on clotting tests and release of tissue factor pathway inhibitor (TFPI). Biosimilarity therefore becomes an issue when generic forms of LMWHs are developed. So far, no bioequivalence study with a generic LMWH has been reported. A generic enoxaparin (test) was compared with the originator (reference) in 20 volunteers after single-dose subcutaneous administration (40 mg enoxaparin sodium, 4000 IU/mL anti-factor Xa (anti-FXa; activity). Target variables were anti-FXa and anti-FIIa activity, activated partial thromboplastin time (aPTT), prothrombinase-induced clotting time (PiCT), and TFPI over 24 hours. The statistical evaluation of the anti-FXa activity profile demonstrated bioequivalence of test and reference with confidence intervals of area under the plasma concentration-time curve (AUC0-tlast) (93%-99%) and Amax (88%-95%). Confidence intervals of AUC(0-tlast) (89%-102%) and Amax (90%-103%) of anti-FIIa activity also fulfill bioequivalence criteria. The 90% confidence interval for the maximum concentration of TFPI ranged from 90% to 113%. The claim of similarity was also supported by aPTT and PiCT profiles. Bioequivalence with the originator enoxaparin could be demonstrated by ex vivo inhibition of FXa and FIIa activity, by coagulation tests (aPTT and PiCT), and by in vivo release of TFPI. Whether such data also prove biosimilarity of the generic enoxaparin needs to be determined.

Pharmacokinetic drug interaction profiles of proton pump inhibitors.

Proton pump inhibitors are used extensively for the treatment of gastric acid-related disorders because they produce a greater degree and longer duration of gastric acid suppression and, thus, better healing rates, than histamine H(2) receptor antagonists. The need for long-term treatment of these disorders raises the potential for clinically significant drug interactions in patients receiving proton pump inhibitors and other medications. Therefore, it is important to understand the mechanisms for drug interactions in this setting. Proton pump inhibitors can modify the intragastric release of other drugs from their dosage forms by elevating pH (e.g. reducing the antifungal activity of ketoconazole). Proton pump inhibitors also influence drug absorption and metabolism by interacting with adenosine triphosphate-dependent P-glycoprotein (e.g. inhibiting digoxin efflux) or with the cytochrome P450 (CYP) enzyme system (e.g. decreasing simvastatin metabolism), thereby affecting both intestinal first-pass metabolism and hepatic clearance. Although interactions based on the change of gastric pH are a group-specific effect and thus may occur with all proton pump inhibitors, individual proton pump inhibitors differ in their propensities to interact with other drugs and the extent to which their interaction profiles have been defined. The interaction profiles of omeprazole and pantoprazole have been studied most extensively. A number of studies have shown that omeprazole carries a considerable potential for drug interactions, since it has a high affinity for CYP2C19 and a somewhat lower affinity for CYP3A4. In contrast, pantoprazole appears to have lower potential for interactions with other medications. Although the interaction profiles of esomeprazole, lansoprazole and rabeprazole have been less extensively investigated, evidence suggests that lansoprazole and rabeprazole seem to have a weaker potential for interactions than omeprazole. Although only a few drug interactions involving proton pump inhibitors have been shown to be of clinical significance, the potential for drug interactions should be taken into account when choosing a therapy for gastric acid-related disorders, especially for elderly patients in whom polypharmacy is common, or in those receiving a concomitant medication with a narrow therapeutic index.