Key Pharmacokinetic Essentials of Fixed-Dosed Combination Products: Case Studies and Perspectives.

Fixed-dose combinations are gaining popularity because they provide convenience while enhancing patient compliance. Literature examples suggest that many fixed-dose combinations are being rationalized and investigated for their potential utility in therapy. This article provides an introspection into the pharmacokinetic essentials that need to be considered prior to implementing a fixed-dose combination strategy. While the drug-drug interaction potential is an important question for the two drugs in a fixed-dose combination, the occurrence of a drug-drug interaction in itself is not a negative outcome for the proposed fixed-dose combination. However, the magnitude of a drug-drug interaction may require a re-assessment of the doses of the two drugs in a fixed-dose combination. Several case studies are provided and discussed to provide a broad perspective on the topic along with a representative framework and strategy on the development of fixed-dose combinations using key pharmacokinetic parameters.