Effects of paroxetine, a CYP2D6 inhibitor, on the pharmacokinetic properties of hydrocodone after coadministration with a single-entity, once-daily, extended-release hydrocodone tablet.

PURPOSE: A single-entity, once-daily, extended-release formulation of hydrocodone bitartrate (HYD) has been developed for the management of moderate to severe chronic pain. Hydrocodone undergoes cytochrome P-450 (CYP)-mediated metabolism involving the CYP3A4 and CYP2D6 isozymes. CYP3A4 yields norhydrocodone, a major inactive metabolite, whereas CYP2D6 yields hydromorphone, a minor active metabolite. This study examined the influence of the coadministration of paroxetine, a strong selective CYP2D6 inhibitor, on the pharmacokinetic properties of hydrocodone (and hydromorphone) in healthy adults. METHODS: In this randomized, double-blind, 2-period, 2-treatment crossover study, 24 healthy subjects received paroxetine 20 mg or placebo once daily for 12 days and an HYD 20-mg tablet on day 10 of each period. FINDINGS: Hydrocodone mean Cmax and t½ and median Tmax values were similar with paroxetine or placebo coadministration (16.8 vs 15.9 ng/mL, 8.5 vs 8.4 hours, and 18.0 vs 18.0 hours, respectively), as were mean AUC0-t and AUC0-∞ values (342.9 vs 325.3 ng · h/mL and 346.3 vs 328.5 ng · h/mL). The 90% CIs of the geometric mean ratios of the hydrocodone AUC and Cmax values were fully within the predetermined range of 80% to 125%, suggesting that there was no effect of multiple doses of paroxetine on systemic exposure to hydrocodone. Mean hydromorphone AUC0-t and Cmax values were decreased with paroxetine versus placebo (0.64 vs 3.8 ng · h/mL and 0.06 vs 0.19 ng/mL), whereas Tmax values remained similar (18.0 vs 16.1 hours, respectively). The mean hydromorphone AUC0-∞ value could not be calculated. Both regimens were well tolerated; after HYD administration, the numbers of adverse events were similar between the 2 treatment regimens, and all adverse events were mild. IMPLICATIONS: In this study, the coadministration of single-dose HYD with paroxetine at steady state did not alter systemic exposure to hydrocodone, suggesting that HYD can be coadministered with CYP2D6 inhibitors at therapeutic doses, without dosage modification.

Once-weekly transdermal buprenorphine application results in sustained and consistent steady-state plasma levels.

CONTEXT: Transdermal formulations of buprenorphine offer controlled delivery of buprenorphine for sustained analgesic efficacy with reduced adverse events (AEs) compared with the other modes of administration. A buprenorphine transdermal system (BTDS) delivering 5, 10, or 20 mcg/hour for seven days is now marketed in the U.S. as Butrans(®) (Lohmann Therapie-System AG, Andernach Germany), a Schedule III single-entity opioid analgesic indicated for the management of moderate and chronic pain in patients requiring continuous around-the-clock analgesia for an extended period. OBJECTIVES: This was a randomized open-label study in healthy subjects to characterize the steady-state buprenorphine pharmacokinetics after the delivery of three consecutive seven-day BTDS applications. METHODS: Thirty-seven subjects were randomized to receive three consecutive BTDS 10 mcg/hour (BTDS 10) patches applied to the deltoid or upper back for seven days each. Blood samples for buprenorphine concentration measurements were taken. Safety was assessed using recorded AEs, clinical laboratory test results, vital signs, pulse oximetry, physical examinations, and electrocardiograms. Patch adhesion assessments were taken. RESULTS: Analysis of Cmin demonstrated that steady state was reached during the first BTDS 10 application. No significant difference in Cmin was observed across the three applications. Total and peak plasma buprenorphine exposures were similar after each of the seven-day administrations of BTDS. CONCLUSION: Three consecutive once-weekly applications of BTDS 10 provided consistent and sustained delivery of buprenorphine. Steady-state plasma concentrations were reached within 48 hours of the first application of BTDS 10. Patch adhesion analysis confirmed the appropriateness of the seven-day application period. Overall, BTDS 10 was safe and well tolerated.

Pharmacokinetics of oral cyanocobalamin formulated with sodium N-[8-(2-hydroxybenzoyl)amino]caprylate (SNAC): an open-label, randomized, single-dose, parallel-group study in healthy male subjects.

BACKGROUND: Vitamin B12 (cobalamin) deficiency may be caused by inadequate dietary intake of B12 or by conditions that result in malabsorption of the vitamin. Crystalline vitamin B12, usually in the form of cyanocobalamin, is administered parenterally (ie, intramuscularly) or orally for treating deficiency states. Intramuscular administration is widely accepted as a treatment method. Oral B12 supplementation is also used, but it is considered to be less reliable. OBJECTIVE: This study was conducted to compare the pharmacokinetics and tolerability of 2 oral formulations of cyanocobalamin-a marketed cyanocobalamin tablet (immediate-release B12 5 mg) and cyanocobalamin formulated with a proprietary carrier, sodium N-[8-(2-hydroxybenzoyl)amino]caprylate (SNAC)-to establish the feasibility of using an absorption enhancer with B12 to improve uptake of the vitamin. This was the first clinical study conducted with the cyanocobalamin/SNAC coformulation. METHODS: An open-label, randomized, single-dose, parallel-group study was conducted in healthy male subjects. Subjects were randomly assigned to 1 of 4 treatment groups: Treatment A subjects (n = 4) received 2 tablets of 5-mg cyanocobalamin formulated with 100-mg SNAC as part of a dose range-finding arm included to determine a dose to provide a measurable concentration of vitamin B12 at all time points when tested with the available vitamin B12 assay; treatment B subjects (n = 6) received 1 tablet of 5-mg cyanocobalamin formulated with 100-mg SNAC; treatment C subjects (n = 6) received 1 commercially available 5-mg cyanocobalamin tablet; and treatment D subjects (n = 4) received commercially available 1-mg cyanocobalamin IV. Treatment A was completed 3 weeks before treatments B, C, and D were studied. Human serum B12 was analyzed by chemiluminescence assay method. Validation procedures established that samples could be diluted up to 100 times without any effects on accuracy and precision. The pharmacokinetic properties of vitamin B12 were characterized by noncompartmental analysis. Vitamin B12 absolute bioavailability estimates were calculated between the oral (A, B, and C) and IV (D) treatments using non-baseline-adjusted vitamin B12 concentrations as well as baseline-adjusted vitamin B12 concentrations, with or without body weight adjustments. Tolerability was evaluated through review or monitoring of medical history, physical examination findings, concomitant medications, vital signs, laboratory tests (hematology, serum chemistry, and urinalysis values), electrocardiography, adverse events, and serious adverse events. RESULTS: Twenty healthy male subjects, aged 20 to 45 years, participated in this study. Based on data from treatment A, a 5-mg cyanocobalamin dose was selected for use with treatments B and C. The oral cyanocobalamin formulation containing SNAC had greater mean absolute bioavailability than the commercial oral formulation (5.09% vs 2.16%, respectively), calculated on AUC(0-last) values uncorrected for baseline, weight, or body mass index. It also had a reduced T(max) compared with the commercial formulation (0.5 hours vs 6.83 hours, respectively). The K(e) was similar between treatments (0.028 1/h vs 0.025 1/h). Comparable results were achieved using corrected values. The cyanocobalamin/SNAC formulation was well tolerated, and there were no reported adverse events. CONCLUSIONS: An oral formulation of 5-mg cyanocobalamin containing 100-mg SNAC, an absorption enhancer, provided significantly improved bioavailability and a significant decrease in T(max) for B12 in a small study of normal healthy subjects compared with a commercially available 5-mg cyanocobalamin oral formulation. Both oral formulations and commercial 1-mg cyanocobalamin IV were well tolerated.

Comparing the efficacy and tolerability of a new daily oral vitamin B12 formulation and intermittent intramuscular vitamin B12 in normalizing low cobalamin levels: a randomized, open-label, parallel-group study.

BACKGROUND: Vitamin B(12) deficiency is routinely treated with parenteral dosing and less often with high-dose oral vitamin B(12). Oral vitamin B(12) formulations have low bioavailability in patients with malabsorption and are considered less reliable than parenteral treatments. OBJECTIVE: The objective of this study was to compare the efficacy and safety profile of a new proprietary oral vitamin B(12) formulation (oral B(12)) with intramuscular (IM) vitamin B(12) (IM B(12)) in restoring normal serum B(12) concentrations in patients with low cobalamin levels (<350 pg/mL). METHODS: Patients were recruited from 5 centers and randomly assigned to receive oral B(12) 1000 µg, taken daily for 90 days, or IM B(12) 1000 µg, given on study days 1, 3, 7, 10, 14, 21, 30, 60, and 90. The patients were aged ≥60 years or aged ≥18 years and had gastrointestinal abnormalities or were on a restricted diet. The primary efficacy outcome compared the proportion of patients in each treatment arm in whom cobalamin levels were normalized (≥350 ng/mL) following 60 days of treatment. Secondary objectives included comparing the efficacy of the 2 formulations after 90 days of treatment, assessing time to normalization of B(12) levels, and evaluating the changes in the levels of biomarkers methylmalonic acid (MMA) and homocysteine (HC). The effect on holotranscobalamin II (active B(12)) levels was assessed as an exploratory end point and correlated to serum cobalamin levels in both treatment groups. Blood samples were collected at baseline (day 1) and on days 15, 31, 61, and 91. RESULTS: Fifty patients were recruited. Forty-eight patients (96.0%) completed the study (22 patients [91.7%] in the oral B(12) group and 26 patients [100%] in the IM B(12) group). All patients (100%) in both treatment groups and in both populations had a cobalamin level ≥350 pg/mL on day 61 and maintained it on day 91. The difference between the IM and oral treatment groups did not reach the planned level of statistical significance (P < 0.05) for mean percent change from baseline (PCFB) in serum cobalamin levels on day 61 and day 91. The difference between the IM and oral treatment groups did not reach the planned level of statistical significance for mean PCFB in serum MMA levels on day 61. There was a statistical difference between the IM and oral treatment groups for mean PCFB in serum MMA levels on day 91 (P = 0.033), with lower values in the oral B(12) group. The difference between the IM and oral treatment groups did not reach the planned level of statistical significance for mean PCFB in plasma HC levels on day 61 and day 91. All patients in each treatment group achieved normalization of serum cobalamin levels by day 15. All patients in both treatment groups and in both populations had plasma holotranscobalamin levels ≥40 pmol/L on day 61 and on day 91. No statistical analysis was planned or performed for safety end points, which were reported only descriptively. Most observed adverse effects were considered mild or moderate in intensity. All adverse effects that were considered severe in intensity were also considered by the investigator to be not related to the study drug. CONCLUSIONS: In this selected study population comprising individuals with low cobalamin levels but who otherwise were in good health, patients received oral B(12) (1000 µg/d) or IM B(12) (1000 µg in 9 injections over 3 months) for a total of 3 months. Both the oral and IM formulations were effective in restoring normal levels of serum cobalamin in all patients studied (100%). Both formulations used in this study were well tolerated at the dose studied. ClinicalTrials.gov identifier: NCT01312831.

Pharmacokinetics and pharmacodynamics of oral heparin solid dosage form in healthy human subjects.

The present investigation determined the molecular structure and the pharmacokinetic and pharmacodynamic profiles of oral unfractionated heparin containing oral absorption enhancer sodium N-[8-(2-hydroxybenzoyl) amino]caprylate, salcaprozate sodium (SNAC) and assessed the safety and tolerability of the orally dosed heparin solid dosage form versus other routes. Sixteen healthy men were included in this single-dose, 3-way crossover, randomized, open-label study. Disaccharide compositional analysis was performed using capillary high-performance liquid chromatography with electrospray ionization mass spectrometry detection. The pharmacodynamics of heparin were obtained from analysis of plasma anti-factor Xa, anti-factor IIa, activated partial thromboplastin time, and total tissue factor pathway inhibitor data. The molecular weight properties and the disaccharide composition of orally administered unfractionated heparin/SNAC and parenterally administered unfractionated heparin are identical and consistent with the starting pharmaceutical standard heparin. Furthermore, the anti-factor Xa/anti-factor IIa ratio achieved is of approximately 1:1. This is the first true pharmacokinetic study to measure the chemical compositions of heparin administered by different routes.