Veterinary fixed-dose antibiotics in Africa: a need for evidence-based regulation.

Fixed-dose combination (FDC) antibiotics are commonly used in animal health; however, their use faces increasing scrutiny due to concerns about unproven efficacy, inappropriate dosing, safety and limited regulatory oversight. We reviewed veterinary drug registries from Kenya, Uganda, Tanzania, Rwanda and Zimbabwe, identifying 2339 registered products, of which 867 (37.1%) contained antibiotics. Among these, 238 (27.5%) were FDCs, representing 45 unique combinations - most commonly two-antibiotic formulations such as penicillin/dihydrostreptomycin, tylosin/doxycycline and trimethoprim/sulfadiazine. Most formulations (77.8%, n = 35) contained two antibiotics, while 15.5% and 6.7% contained three and four antibiotics, respectively. Nearly half of FDC brands (47.1%, 112/238) contained antibiotics from both the Caution and Prudence categories, while 39.5% (94/238) contained antibiotics from the Prudence category alone. Notably, 8.4% (20/238) of FDC brands contained colistin, with or without enrofloxacin, and 5% (12/238) included vitamin combinations. Some antimicrobial FDCs may be clinically justified, for example, by broadening spectrum or achieving pharmacological synergy, but many lack a clear therapeutic rationale, underscoring the need for an evidence-based regulatory review and clearer criteria for appropriate veterinary FDCs.