A wearing off of response to onabotulinumtoxinA (onabotA) during the first treatment cycle may be common in individuals with chronic migraine (CM), but may be mitigated by dosage increases during subsequent cycles, according to a study published in Pain Medicine.

OnabotA, with its extended duration of action, offers safe and effective prophylaxis against CM, with a cumulative effect after repeated cycles. Clinical worsening has been observed after 8 to 10 weeks of initially successful treatment.

In this longitudinal retrospective study, data from 193 adult patients with CM (87% women; mean age, 43.4 years; mean migraine diagnosis duration, 25.2 years; mean CM duration, 43.2 months) who received onabotA treatment between May 2012 and December 2017 were examined. The cohort was followed through 24 weeks after initial treatment, with full-length and wearing off responses defined as ≥50% headache days reduction (as recorded in a standard headache diary) for ≥12 weeks and ≤10 weeks, respectively. The primary outcome was the incidence of the wearing off response.

There were 91 “full-length” participants (47.1%; 90.2% women; mean age, 42.02 years; mean onset age, 18.62 years; mean CM duration, 32.55 months) and 45 “wearing off” patients (23.3%; 84.4% women; mean age, 41.49 years; mean onset age, 18.09 years; mean CM duration, 26.02 months) . Baseline demographic and clinical characteristics were comparable in both groups, and no significant clinical predictors of response were identified.

In participants indicating a wearing off of the response, 68.9% received higher doses of onabotA during the second treatment cycle, which resulted in a longer-lasting response (up to 12 weeks) in 74.2% of these individuals.

Adverse effects were reported by 21.4% of patients, but none of these individuals discontinued onabotA therapy as a result. The majority of adverse effects were muscle weakness, neck pain, and/or mild aesthetic changes.

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Study limitations include its observational design, lack of a control group, and the low number of patients.

“This is the first study to describe a wearing off response to onabotA defined by a positive clinical but short-lasting (≤10 weeks) effect of onabotA for CM during the first treatment cycles,” noted the authors.

Reference

Quintas S, García-Azorín D, Heredia P, Talavera B, Gago-Veiga AB, Guerrero ÁL. Wearing off response to onabotulinumtoxinA in chronic migraine: analysis in a series of 193 patients [published online January 17, 2019]. Pain Med. doi:10.1093/pm/pny282

This article originally appeared on Clinical Pain Advisor