Fixed-Dose Combinations (FDC)

Definition & overview

• Fixed-dose combination (FDC) — a pharmaceutical preparation containing two or more drugs combined in a single dosage form (one tablet, capsule or formulation) in a fixed, predetermined, non-adjustable ratio of doses — the patient receives all components together each time the unit is taken.
• Free (loose) combination — the same drugs co-prescribed as separate units that the prescriber can independently titrate. The defining feature of an FDC is the loss of independent dose adjustment once the ratio is fixed.
• FDCs are among the most common product types in the Indian market, where polypharmacy combination products proliferate.
• The clinical pharmacology of an FDC sits at the intersection of pharmacodynamics (does the combination make therapeutic sense?), pharmacokinetics (do the components behave compatibly?), prescribing rationality and drug regulation — so it is examined under "rational drug use", not under a single drug class.
• Regulatory status (India) — an FDC is legally treated as a "new drug" the first time two approved drugs are combined, and therefore requires central (DCGI/CDSCO) safety-and-efficacy approval before manufacture (see §v). [CDSCO]