Comparison of formulation characteristics of drugs and dietary supplements containing alpha-lipoic acid relevant to therapeutic efficacy.

Abstract

Healthcare professionals lack the knowledge about the impact of formulations on treatment effectiveness. This is further complicated by the existence of dietary supplements containing the same active pharmaceutical ingredients (API) as drug formulations [e.g., alpha-lipoic acid (ALA)], to which the strict formulation testing requirements do not apply. This research aimed to compare ALA-containing drugs and dietary supplements through the determination of uniformity of content, disintegration time and dissolution rates. A total of seven different ALA formulations (5 dietary supplements, 2 drugs) were tested for uniformity of content, disintegration time and dissolution rates. All tests were performed in accordance with the 10th European Pharmacopoeia. ALA was determined spectrophotometrically. Uniformity of content testing revealed larger variations of ALA content in three formulations of dietary supplements. Dissolution curves generated at 50 and 100 rpm differed significantly. Testing requirements were met only by one dietary supplement at 50 rpm, and one drug and two dietary supplements at 100 rpm. Disintegration testing showed limited impact on the release kinetic of ALA, as opposed to formulation type. Considering the lack of regulation on dietary supplement formulations and the variable success of them conforming to pharmacopoeial requirements, it is an imperative for stricter regulations on the dietary supplements' formulations to be imposed globally.