Pharmacokinetics of a Novel Anagrelide Extended-Release Formulation in Healthy Subjects: Food Intake and Comparison With a Reference Product

Anagrelide is an established therapy for essential thrombocythemia. Common adverse effects have been linked to peak plasma concentrations of anagrelide and its 3OH metabolite. Our study was performed to investigate the pharmacokinetics (PK) of a novel anagrelide extended-release (AER) formulation and its active metabolites. Thirty healthy volunteers were randomized to receive either 2 mg AER (under fasting and fed conditions) or 2 mg commercially available reference product (CARP) in an open-label, 3-way crossover trial with washout periods of 6 days. Plasma concentrations of anagrelide and its active metabolites were assessed by tandem mass spectrometry. The PK differed significantly between all treatment periods. Bioavailability of AER was 55% of the CARP under fasting conditions and 60% under fed conditions. Cmax , AUCt, and AUC∞ were significantly higher and Tmax and T1/2 were significantly shorter after the CARP compared with AER. Food had a significant impact on the PK of AER, increasing the Cmax and AUCt while reducing the T1/2 , plateau, and mean residence time. Both formulations were well tolerated, with a trend toward more frequently occurring adverse events after the CARP. The PK of AER and the CARP differed significantly in all parameters. Food enhanced the bioavailability of AER.

Pharmacokinetics and bioequivalence evaluation of cyclobenzaprine tablets

The purpose of this study was to investigate cyclobenzaprine pharmacokinetics and to evaluate bioequivalence between two different tablet formulations containing the drug. An open, randomized, crossover, single-dose, two-period, and two-sequence design was employed. Tablets were administered to 23 healthy subjects after an overnight fasting and blood samples were collected up to 240 hours after drug administration. Plasma cyclobenzaprine was quantified by means of an LC-MS/MS method. Pharmacokinetic parameters related to absorption, distribution, and elimination were calculated. Cyclobenzaprine plasma profiles for the reference and test products were similar, as well as absorption pharmacokinetic parameters AUC (reference: 199.4 ng ∗ h/mL; test: 201.6 ng ∗ h/mL), Cmax (reference: 7.0 ng/mL; test: 7.2 ng/mL), and T(max) (reference: 4.5 h; test: 4.6 h). Bioequivalence was evaluated by means of 90% confidence intervals for the ratio of AUC (93%-111%) and C(max) (93%-112%) values for test and reference products, which were within the 80%-125% interval proposed by FDA. Cyclobenzaprine pharmacokinetics can be described by a multicompartment open model with an average rapid elimination half-life (t(1/2)β) of 3.1 hours and an average terminal elimination half-life (t(1/2)γ) of 31.9 hours.

Steady-state pharmacokinetics of once-daily cyclobenzaprine extended release: a randomized, double-blind, 2-period crossover study in healthy volunteers

BACKGROUND

The single-dose pharmacokinetic profile of cyclobenzaprine extended-release (CER) has been previously characterized and compared with the pharmacokinetics of cyclobenzaprine immediate-release (CIR) administered 3 times daily for 3 doses.

OBJECTIVE

The objective of this study was to characterize the multiple-dose pharmacokinetic properties of once-daily CER 30 mg and CIR 10 mg TID formulations in healthy volunteers.

METHODS

In this double-blind, single-center, 2-period crossover study, healthy subjects were randomized to dosing sequences with once-daily CER 30 mg or CIR 10 mg TID for 7 days. Subjects crossed over to the alternative regimen following a 14-day washout period. Pharmacokinetic assessments at steady state included area under the plasma cyclobenzaprine concentration-time curve over the dosing interval (AUC(0-τ,ss)), peak plasma cyclobenzaprine concentration (C(max,ss)), time to observed C(max) (T(max,ss)), observed minimum cyclobenzaprine concentration (C(min,ss)), average cyclobenzaprine concentration (C(avg,ss)), accumulation ratio (R(ac)), and terminal elimination half-life (t(½)). Tolerability and safety assessments were conducted.

RESULTS

A total of 36 subjects were randomized; 34 completed both dosing periods (1 subject was lost to follow-up, 1 withdrew consent). Steady state was reached for CER 30 mg on day 7. Mean C(max,ss), C(min,ss), and C(avg,ss) were 41.1, 21.4, and 31.4 ng/mL, respectively. The median T(max,ss) for CER 30 mg was 7.0 hours, with a mean t(½) of 34.8 hours. At steady state, CER produced a sustained plasma cyclobenzaprine concentration with a single peak in plasma concentration during the 24-hour dose interval. The R(ac) for CER was 2.65. Because of a protocol violation (insufficient data), no steady-state pharmacokinetic assessments could be performed for CIR. Most adverse events were mild or moderate in intensity. Somnolence was the most frequently reported adverse event (100% of subjects) in those receiving CER, followed by dry mouth (58%), dizziness (19%), and headache (17%).

CONCLUSIONS

Once-daily CER 30 mg delivered sustained plasma cyclobenzaprine levels over 24 hours at steady state. Owing to a protocol violation, steady-state pharmacokinetic properties for CIR could not be assessed.

Efficacy and tolerability of cyclobenzaprine extended release for acute muscle spasm: a pooled analysis

OBJECTIVE

To assess the efficacy and tolerability of once-daily cyclobenzaprine extended release (CER) 15 and 30 mg in relieving acute muscle spasm.

METHODS

This is a pooled analysis of 2 randomized, double-blind, placebo-controlled, parallel-group studies of identical design. Adults with local muscle spasm associated with neck/low back pain were randomized to treatment with once-daily CER 15 (n = 127) or 30 mg (n = 126), cyclobenzaprine immediate release (CIR) 10 mg 3 times daily (n = 123), or placebo (n = 128) for 14 days. Primary outcome measures were the patient's rating of medication helpfulness and physician's clinical global assessment of response to therapy at day 4.

RESULTS

Of 504 patients, 330 (65.5%) completed the studies. Significantly greater improvements in patient's rating of medication helpfulness were reported with CER 15 and 30 mg versus placebo at day 4 (P < 0.025). No differences were reported between groups in physician's clinical global assessment. Significantly greater improvements (P < 0.025) were noted in patient-rated secondary measures versus placebo: relief from local pain at days 4 (CER 30 mg) and 8 (CER 15 and 30 mg), global impression of change at days 4 and 8 (CER 30 mg), and restriction of movement at day 4 (CER 30 mg). Improvements with CER 15 and 30 mg on most efficacy measures were similar to CIR. There was less reported daytime drowsiness with CER 15 and 30 mg than with CIR (P < 0.05). Most adverse events (AEs) were mild in intensity. The most common AEs for all groups were dry mouth, constipation, dizziness, headache, and somnolence. The rate of somnolence reported as an AE was lower (P < 0.05) with CER 15 (0.8%) and 30 mg (1.6%) than with CIR (7.3%).

CONCLUSION

Once-daily CER was effective in relieving acute muscle spasm based on patient's rating of medication helpfulness at day 4 and was generally well tolerated with a low rate of reported somnolence.