Antimicrobial agent	Continuous prophylaxis (daily dosage)*	Cost (brand)†	Postcoital prophylaxis (one-time dose)‡	In retail discount programs§
Cephalexin (Keflex)	125 to 250 mg	$14 ($66); only available in 250-mg capsule	250 mg	✓
Ciprofloxacin (Cipro)	125 mg	$12 ($68); half tablet (250 mg) for 30 days	125 mg	✓
Nitrofurantoin (Macrodantin)	50 to 100 mg	$28 ($68) for 50-mg dose	50 to 100 mg
Norfloxacin (Noroxin)	200 mg	NA ($63); half tablet (400 mg) for 30 days	200 mg
Trimethoprim (Proloprim)	100 mg	$20 (NA)	100 mg
Trimethoprim/sulfamethoxazole (Bactrim, Septra)	40/200 mg	$16 ($26); half tablet for 30 days	40/200 to 80/400 mg	✓