Drug Interaction Study of Safinamide and a BCRP Substrate, Diclofenac, Concomitantly Administered to Healthy Volunteers

According to Xadago™ SmPC, safinamide may transiently inhibit BCRP, therefore a time interval of 5 h should be kept between dosing of safinamide and medicinal products that are BCRP substrates with a Tmax ≤2 h (e.g. diclofenac, pitavastatin, pravastatin, ciprofloxacin, methotrexate, topotecan or glyburide).

Following a specific request of EMA CHMP, the present interaction study in healthy male and female volunteers was conducted to determine if co-administration of safinamide with a BCRP substrate alters plasma exposure of the BCRP substrate in vivo.

Diclofenac was chosen among the other BCRP substrates considering its large use in the general population. Diclofenac in fact is an important analgesic and anti-inflammatory drug, widely used for the treatment of postoperative pain, rheumatoid arthritis, and chronic pain. Consequently, diclofenac is often used in combination regimens and undesirable drug-drug interactions may occur.

Voltaren®, 50 mg soluble tablets, was selected among other possible diclofenac products because with this formulation peak concentration of diclofenamic acid is achieved at approximately 1 h, i.e. in less than 2 h.

The present interaction study was designed in agreement with the FDA Guideline on Drug Interaction studies, taking also in consideration the EMA guideline on the Investigation of drug interactions.