Obstetric: Do not use unless potential maternal benefit outweighs potential risk to fetus. Use Cautiously in: Renal impairment (efficacy may be ↓; dose ↓ recommended for CCr ≤50 mL/min); Geriatric: Consider age-related ↓ in renal function, adjust dose accordingly (↑ risk of adverse renal reactions); Lactation: Use cautiously; Pediatric: Safety and effectiveness not established.