A model-based approach to treatment comparison in acute migraine

Population Pharmacokinetic Analysis of Zolmitriptan and Its Metabolite in Adults and Adolescents to Support Dose Selection in Children With Migraine

Zolmitriptan is a serotonin (5-HT) _1B/1D receptor agonist effective for the treatment of migraine. This analysis aimed to develop a population pharmacokinetic (PK) model for zolmitriptan and its active metabolite in adults and adolescents and provide appropriate dosing regimens to be used in clinical trials for children 6-11 years old. The data from a single-dose clinical study of 5.0-mg zolmitriptan nasal spray (ZNS) conducted in adult and adolescent patients with migraine between migraine attacks was applied. Similar plasma concentration profiles of zolmitriptan and its metabolite, 183C91, were observed in adults and adolescents. A 1-compartment model with first-order absorption and first-order elimination reasonably described the zolmitriptan PK. With a portion of elimination of zolmitriptan being treated as the conversion from zolmitriptan to 183C91, the disposition of 183C91 was described by a 1-compartment model with first-order elimination. The estimated typical apparent volume of distribution and clearance of zolmitriptan were 136 L and 121 L/h, respectively, with 56.5% and 42.6% between-subject variability, respectively. Based on the simulation results with the final population PK model, a body weight-based dosing scheme of 5.0 and 2.5 mg ZNS in children greater than and less than 50 kg is recommended to achieve exposures similar to those of the adult and adolescent population administered 5.0 mg ZNS. The recommended doses for children to achieve exposure similar to that observed in adults given 2.5 mg ZNS are 2.5 mg (≥50 kg) and 1.0 mg (15-50 kg). These dosing regimens could be used in future clinical trials.

Fractionation of daily dose increases the predicted risk of severe sorafenib-induced hand-foot syndrome (HFS)

OBJECTIVES

The objective was to quantify the risk dynamics for the sorafenib-induced hand-foot syndrome (HFS) and to explore by simulations the dose-toxicity relationships according to different dosing regimens.

PATIENTS AND METHODS

Eighty-nine patients treated with sorafenib were considered: Treatment duration and regimen, and number and frequency of HFS observations were highly variable. A nonlinear mixed-effect model was built to link sorafenib administrations to the risk of each HFS score, through a latent variable model. Model evaluation was driven by goodness-of-fit and simulation-based diagnostics. Impact of sorafenib regimen on HFS dynamics was evaluated by simulations. A surrogate measure of benefit-to-risk ratio was calculated by using the concept of utility function, accounting for efficacy on tumor growth inhibition and severe HFS risk.

RESULTS AND DISCUSSION

An original pharmacokinetic-pharmacodynamic model for sorafenib-induced HFS, including the kinetics of a latent variable model, relating sorafenib administrations, per se its exposure, to HFS dynamics is proposed. From the model simulations, it appears that the more the daily dose is fractioned, the more the patients are at risk of HFS. Interestingly, the number of daily occasions was found more influential than the dose itself. Taking into account tumor growth inhibition in the utility function, the twice-daily administration schedule is favored for daily doses >600 mg. This approach illustrates how understanding the dynamic relationship between drug administrations and a limiting adverse event may help to control toxicity and adequately adjust treatment modalities.

Randomized trial of sumatriptan and naproxen sodium combination in adolescent migraine

BACKGROUND

Treatment of adolescent migraine remains a significant unmet medical need. We compared the efficacy and safety of 3 doses of sumatriptan and naproxen sodium (suma/nap) combination tablets to placebo in the acute treatment of adolescent migraine.

METHODS

This randomized, parallel group study in 12 to 17 year olds required 2 to 8 migraines per month (typically lasting >3 hours untreated) for ≥ 6 months. Subjects entered a 12-week run-in phase, treating 1 moderate-to-severe migraine (attack 1) with single-blind placebo. Subjects reporting headache pain 2 hours after dosing were randomly assigned into a 12-week double-blind phase, treating 1 moderate-to-severe migraine (attack 2) with placebo (n = 145), suma/nap 10/60 mg (n = 96), 30/180 mg (n = 97), or 85/500 mg (n = 152). The primary end point was the percentage of subjects pain-free at 2 hours.

RESULTS

The attack 2 adjusted (age; baseline pain severity) 2-hour pain-free rates were higher with suma/nap 10/60 mg (29%; adjusted P = .003), 30/180 mg (27%; adjusted P = .003), and 85/500 mg (24%; adjusted P = .003) versus placebo (10%). Posthoc primary end-point analyses did not demonstrate differences among the 3 doses or an age-by-treatment interaction. Statistically significant differences were found for 85/500 mg versus placebo for sustained pain-free 2 to 24 hours (23% vs 9%; adjusted P = .008), 2-hour photophobia-free (59% vs 41%; adjusted P = .008), and 2-hour phonophobia-free (60% vs 42%; adjusted P = .008). Analyses of other pain, associated symptoms, rescue medication use, and health outcome end points supported higher efficacy for active doses versus placebo. All active doses were well tolerated.

CONCLUSIONS

All doses of suma/nap were well tolerated, providing similarly effective acute treatment of adolescent migraine pain and associated symptoms, as compared with placebo.

Analysis of the relationship between age and treatment response in migraine

In migraine, headache severity varies with age. As a consequence, the effectiveness of medication may also depend on a patient's age. The purpose of this study was to assess the combined effect of age and drug treatment on headache characteristics. Using data from clinical trials of sumatriptan in adolescents and adults, we show how the interaction between age and drug exposure can be parameterised as a covariate on a Markov model that describes the decline of headache severity over three clinically defined stages (no relief, relief and pain-free status). The model explains important clinical observations: (i) the rates at which the pain relief and pain-free status were attained were found to be inversely related to age; (ii) in placebo-treated patients, the mean transit time from 'no relief' to 'relief' is 3 h for young adolescents and increases to 6 h for patients aged >or= 30 years; and (iii) sumatriptan reduces the transit time to 2 h, irrespective of age. These findings indicate that the therapeutic gain over placebo increases with age. Prospective studies of antimigraine drugs should take this relationship into account when extrapolating efficacy data from adults to adolescents.

Relevance of absorption rate and lag time to the onset of action in migraine

OBJECTIVE

The objective of this analysis was to simulate the performance of oral triptan formulations with varying absorption characteristics and their impact on the onset and magnitude of the antimigraine effect using a Markov model for migraine attacks.

ANALYSIS

Sumatriptan pharmacokinetic data were obtained from clinical pharmacology studies in which marketed solid formulations were administered. Based on a population pharmacokinetic model, mean concentration-time profiles were generated by varying the absorption rate constant and lag time. Subsequently, the simulated profiles were evaluated in a disease model of migraine to predict the onset and duration of the effect (the pain-free, pain-relief response).

RESULTS

Based on a therapeutic dose of 50 mg of sumatriptan, a maximum gain in the pain-free response of 12% was achieved with an increased absorption rate. This gain in the response was reached approximately 0.5 hours after administration. A decrease only in the lag time with respect to the currently available formulations (i.e. 0.24 hours) resulted in a maximum gain of 5% in the pain-free response, which in contrast may not be interpreted as clinically relevant.

CONCLUSION

Model-based predictions suggest that increases in the absorption rate of the currently marketed oral formulation of sumatriptan result in a gain in the pain-free response that is both clinically and statistically relevant.