The effect of laquinimod, a novel immuno-modulator in development to treat Huntington disease, on the pharmacokinetics of ethinylestradiol and levonorgestrel in healthy young women

PurposeLaquinimod is an orally dosed immuno-modulator currently under development for Huntington's disease (HD). Preclinical findings suggest potential teratogenicity of laquinimod, thus the reproductive ability of females with HD treated with laquinimod needs to be closely managed. Because combined oral contraceptives (COC) are often used in this context, the pharmacokinetics of COC containing ethinylestradiol (EE) and levonorgestrel (LNG) in combination with laquinimod (0.6mg/day) was evaluated.MethodsIn this randomized, phase-1 single-center, double-blind, placebo-controlled, 2-way crossover drug-drug interaction (DDI) study in 48 healthy premenopausal women, COC were administered in a 28-day regimen of 21days followed by 7 pill-free days for 4cycles and laquinimod or placebo was administered for 28days in cycle 1 and cycle 3 starting 7days prior to COC administration. Blood samples for pharmacokinetic profiling of laquinimod, EE and LNG were collected on day 21 and day 22 of Cycles 1 and 3 pre-dose and multiple times post-dose.ResultsThe ratio of geometric means and 90% confidence intervals for AUC(0-24) and C-max of EE and LNG with and without laquinimod were all within the bioequivalence range (80 to 125%). Laquinimod pharmacokinetics was consistent with those observed in previous studies. The adverse event profile was in line with the current knowledge on the safety profile of both drugs, with headache as the most frequently reported treatment-related adverse event.ConclusionThe combination of COC and laquinimod treatment was found to be safe, tolerable, and devoid of any noticeable pharmacokinetic interaction.