Inhaled drug therapy development for the treatment of migraine

In-vitro and in-vivo respiratory deposition of a developed metered dose inhaler formulation of an anti-migraine drug

Enhancement of zolmitriptan bioavailability through development of micronized zolmitriptan pressurized metered dose inhaler (MDI) as an alternative to its traditional drug delivery systems. A reversed phase HPLC method for zolmitriptan determination was developed and evaluated. Micronized zolmitriptan MDI formulations were prepared using two different propellants. The prepared formulations were evaluated for mean shot weight, drug content, and leakage rate in addition to in-vitro deposition using next generation impactor where mass median aerodynamic diameter (MMAD), geometric standard deviation (GSD), fine particle dose, fine particle fraction (FPF), emitted dose (ED), and dispersibility were determined. The selected formulation was evaluated for in-vivo bronchial absorption in rats. The physicochemical characters of the prepared formulations were found to be dependent mainly on the vapor pressure of the used propellant. MDI formulation prepared with HFA 134a propellant was found to have the lowest MMAD (3.47 ± 0.65) with GSD of 2.3 ± 0.4. It also had the highest FPF (41.9), ED (89.26 ± 2.35) with dispersibility of 46.9%. This formulation, when applied to rats, resulted in faster T_max (27 ± 5 min) with higher C_max (1236 ± 116 ng/mL) and AUC_(0-12) (3375 ± 482 ng/mL·h) over the oral tablet. Its relative bioavailability was 72.7% which was 1.25 times higher than the oral tablet relative bioavailability. Zolmitriptan MDI formulation was developed using micronized zolmitriptan powder without further modification or particle engineering. The developed formulation using HFA 134a propellant could be favorable alternative, with enhanced bioavailability, to zolmitriptan oral tablet for acute migraine treatment.

The discovery and development of inhaled therapeutics for migraine

INTRODUCTION

Migraine is a disabling primary headache disorder that requires effective treatments. Inhalation is currently being explored for the delivery of drugs for migraine. Pulmonary-route delivery of drugs shows potential advantages for its use as a treatment, particularly compared the oral route. Areas covered: The authors highlight the current state of the literature and review multiple therapies for migraine-utilizing inhalation as the route of administration. The following therapeutics are discussed: inhaled ergotamine, inhaled dihydroergotamine mesylate (MAP0004), inhaled prochlorperazine, and inhaled loxapine. Coverage is also given to normobaric oxygen, hyperbaric oxygen, and nitrous oxide therapies. Expert opinion: Inhalation of MAP0004 showed promising results in terms of efficacy for acute migraine treatment in phase 3 studies, together with a more favorable tolerability profile compared to parenteral dosing and a better pharmacokinetic profile versus oral or intranasal delivery. In phase 2 trials, inhaled prochlorperazine shows good pharmacokinetics and efficacy, in contrast to inhaled loxapine that did not provide encouraging results in terms of efficacy. The authors see the potential for the use of dihydroergotamine mesylate in clinical practice pending regulatory approval.

Orally inhaled migraine therapy: Where are we now?

Migraine is a debilitating disease that affects 9% of men and 19% of women worldwide with high socio-economic and personal impact. Surveys indicate that migraineurs are among the most dissatisfied with available therapeutic options, predominantly given via oral or injectable routes, citing side effects as the primary complaint. Orally inhaled therapies have the potential to offer faster onset of action with fewer side effects compared to existing therapies, yet development has stalled. Despite emerging therapies such as calcitonin gene-related peptide antagonists, there are still good opportunities for repositioning migraine drugs via the inhaled route.

Inhalation delivery of complex drugs-the next steps

Oral inhalation offers the opportunity of targeting drugs locally to different regions of the respiratory tract or alternatively, using the high surface area of the alveoli for systemic delivery. Pulmozyme and the inhaled insulins (i.e. Exubera and Afrezza) are examples of the scope of pulmonary drug delivery of biopharmaceuticals-albeit with strikingly different commercial success. Particularly, the failure of Exubera and the subsequent overreactions (e.g. the unsubstantiated lung cancer fear), lastingly stunned the field of systemically inhaled protein and peptide drugs. Building on the lessons learned from these early products, a new wave of inhaled biomolecules has recently entered clinical trials. Moreover, oral inhalation has become an attractive alternative for the delivery of small molecules with difficult oral pharmacokinetics and/or extensive liver first-pass metabolism. Advances in inhaler design and our increased understanding of lung physiology continue to make oral inhalation of complex drugs an attractive therapeutic option.