Class and agent	Half-life*	Route of administration	Dosage adjustment required	Significant adverse effects†	Significant drug interactions‡
First generation
Nalidixic acid (NegGram)	60 to 90 minutes	Oral	Renal impairment		Warfarin (Coumadin)
Cinoxacin (Cinobac)	1.1 to 2.7 hours	Oral	Renal impairment	Hypersensitivity (fewer than 3 percent of recipients)
Second generation
Norfloxacin (Noroxin)	2.3 to 5.5 hours	Oral	Renal impairment		Warfarin, cyclosporine (Sandimmune)
Lomefloxacin (Maxaquin)	7 to 8.5 hours	Oral	Renal impairment	Phototoxicity, headache (3 to 44 percent of recipients), abdominal pain (11 percent), nausea (5.6 percent)
Enoxacin (Penetrex)	3.3 to 7 hours	Oral	Renal or hepatic impairment (patients with advanced cirrhosis)	Phototoxicity (mild)	Warfarin, ranitidine (Zantac), bismuth subsalicylate, theophylline, caffeine
Ofloxacin (Floxin)	5 to 8 hours	Oral, intravenous	Renal or hepatic impairment (patients with severe disease)	Insomnia (13 percent of recipients)	Warfarin
Ciprofloxacin (Cipro)	3 to 5.4 hours	Oral, intravenous	Renal impairment	Nausea, vomiting, abdominal pain	Warfarin, theophylline, caffeine, cyclosporine, glyburide (Micronase)
Third generation
Levofloxacin (Levaquin)	6 hours	Oral, intravenous	Renal impairment	Headache, nausea (6.6 percent of recipients), diarrhea
Sparfloxacin (Zagam)	21 hours	Oral	Renal impairment	Phototoxicity (8 percent of recipients), QT-interval prolongation, torsades des pointes	Drugs that prolong the QT interval, including class I antiarrhythmics, tricyclic antidepressants, phenothiazines, cisapride (Propulsid),§ pentamidine (Pentam) and erythromycin
Gatifloxacin (Tequin)	7 hours	Oral, intravenous	Renal impairment		Same as for sparfloxacin
Moxifloxacin (Avelox)	12 hours	Oral	Hepatic impairment	QT-interval prolongation	Same as for sparfloxacin
Fourth generation
Trovafloxacin (Trovan) Alatrofloxacin (Trovan IV)	7.8 hours	Oral	Hepatic impairment (patients with mild to moderate cirrhosis)	Dizziness (2.4 to 11 percent of recipients), severe hepatotoxicity (rare), candidal vaginitis (1 to 10 percent)	Morphine, citric acid–sodium citrate (Bicitra)
		Intravenous