Lack of a Clinically Significant Pharmacokinetic Interaction Between Pregabalin and Thioctic Acid in Healthy Volunteers.

Purpose: Pregabalin and thioctic acid are likely to be used concomitantly for the treatment of painful diabetic neuropathy. In this study, the pharmacokinetic interaction between pregabalin and thioctic acid was investigated at steady state.

Methods: A randomized, open-label, 6-sequence, 3-period, 3-treatment crossover study was conducted in 42 healthy male volunteers. The volunteers randomly received pregabalin 300 mg BID for 6 times, thioctic acid 600 mg once daily for 3 times, or the combination of pregabalin and thioctic acid. Serial blood samples were collected up to 24 hours after the last dosing in each period. Pharmacokinetic parameters were calculated by using noncompartmental analysis methods.

Findings: The mean concentration-time curves were similar between each drug alone and in combination with the other drug. The 90% CIs of the geometric mean ratios with and without the co-administered drug for C at steady state and AUC during the dosing interval were well within the conventional bioequivalence range of 0.8 to 1.25, except for C at steady state for thioctic acid, which barely exceeded only the lower bound (0.78-1.15). Co-administered pregabalin and thioctic acid was well tolerated.

Implications: Repeatedly administered pregabalin and thioctic acid do not interact pharmacokinetically. This study suggests that the combination of pregabalin and thioctic acid can safely be administered concomitantly without dose adjustment. ClinicalTrials.gov identifier: NCT01808300.