Dodick, DW

Background: Dihydroergotamine (DHE), a proven migraine treatment, currently has product labeling warning against concomitant use of CYP3A4 inhibitors because of potential drug interactions. However, no reported studies of such interactions with DHE administered by any route are available. Methods: The pharmacokinetics (PK) of MAP0004, an investigative inhaled DHE formulation, were assessed in human subjects with and without CYP3A4 inhibition by ketoconazole to evaluate the potential for drug interaction, elevation of DHE levels, and increased adverse effects. Results: After MAP0004 alone vs. MAP0004 plus ketoconazole, the DHE maximum concentrations (C max ) and area-under-the-curve (AUC 0–48 and AUC 0–∞ ) were not statistically significantly different nor was the C max of the primary metabolite, 8’-OH-DHE. A difference in 8’-OH-DHE AUCs was observed between MAP0004 with and without ketoconazole; however, the concentrations were very low. MAP0004 was well tolerated after both treatments. Conclusions: This study demonstrated that CYP3A4 inhibition had little to no effect on DHE PK after MAP0004 administration, apparently because of its high systemic and low gastrointestinal bioavailability. CYP3A4 inhibition slowed elimination of the metabolite 8’-OH-DHE, but concentrations were too low to be pharmacologically relevant.

In 1991 the Clinical Trials Subcommittee of the International Headache Society (IHS) developed and published its first edition of the Guidelines on controlled trials of drugs in episodic migraine because only quality trials can form the basis for international collaboration on drug therapy, and these Guidelines would ‘improve the quality of controlled clinical trials in migraine’. With the current trend for large multinational trials, there is a need for increased awareness of methodological issues in clinical trials of drugs and other treatments for chronic migraine. These Guidelines are intended to assist in the design of well-controlled clinical trials of chronic migraine in adults, and do not apply to studies in children or adolescents.

Thirty to forty percent of migraineurs do not respond to any given triptan treatment. We identified clinical variables that significantly predict therapeutic non-response and evaluated the efficacy of eletriptan (20, 40 and 80 mg) and sumatriptan (100 mg) vs. placebo in a subgroup of patients with all predictor variables. First-attack data were pooled from 10 randomized, double-blind, placebo-controlled migraine trials ( n = 8473). Multivariate regression analyses identified three significant baseline predictors of failure to achieve 2-h pain-free response: severe headache pain, presence of photophobia/phonophobia and presence of nausea. Time of dosing following headache onset did not influence 2-h pain-free response. Among patients with all three risk factors ( n = 2010; 24± of total sample), 2-h pain-free response was significantly higher in patients receiving all three doses of eletriptan or sumatriptan vs. placebo (all P< 0.01). Thus, eletriptan and sumatriptan are efficacious in difficult-to-treat patients at high risk for non-response to triptans.

If treatment-emergent central nervous system (CNS) symptoms following triptan therapy represent direct pharmacological effects of the drug, they should occur independent of response to active drug. However, if they represent unmasking of neurological symptoms of the migraine attack after pain is relieved, they should be more common in responders both to active drug and to placebo. To explore this issue, we evaluated the relationship between the CNS adverse events and treatment response following triptan or placebo treatment. We used pooled data from seven double-blind, placebo-controlled trials involving eletriptan 20 mg (E20, n = 402), eletriptan 40 mg (E40, n = 1870), eletriptan 80 mg (E80, n = 1393), sumatriptan 100 mg (S100, n = 275) and placebo (Pbo, n = 1024). Somnolence was more prevalent among 2 h headache responders than non-responders for all treatments, including E80 (8.8% vs. 5.0%; P < 0.05), E40 (6.4% vs. 5.0%; NS), E20 (4.0% vs. 2.0%; NS), S100 (4.7% vs. 3.2%; NS) and Pbo (7.6% vs. 3.0%; P < 0.05). Similarly, the incidence of asthenia was higher among patients who responded to treatment compared with those who did not respond to E80 (15.2% vs. 7.8%; P < 0.05), E40 (6.5% vs. 3.6%; P < 0.05), E20 (6.5% vs. 1.0%; P < 0.05), S100 (10.1% vs. 4.7%; NS) and Pbo (4.4% vs. 2.7%; NS). The generally higher rates of somnolence and asthenia in patients who respond to treatment suggests that these treatment-emergent neurological symptoms may represent the unmasking of CNS symptoms associated with the natural resolution of a migraine attack, rather than simply representing drug-related side-effects. The rate of somnolence in placebo responders is comparable to that in responders to E40 and E80, indicating that somnolence is related, at least in some important part, to headache relief and not treatment.