Agents	Preferred dosing	Dosage forms	Advantages	Disadvantages
Basic regimens (preferred)
Zidovudine (Retrovir) plus lamivudine (Epivir)	Zidovudine: 300 mg twice daily or 200 mg three times daily, with food	Zidovudine: 100-mg capsules and 300-mg tablets	Zidovudine associated with decreased risk of HIV transmission; serious toxicity is rare when used for postexposure prophylaxis; side effects are predictable and manageable with antimotility and antiemetic agents; can be used during pregnancy; can be given as a single tablet twice daily.	Side effects are common (especially nausea and fatigue) and may result in low adherence; potential source virus resistance; potential for delayed toxicity unknown.
	Lamivudine: 300 mg daily or 150 mg twice daily	Lamivudine: 150- and 300-mg tablets
Combination therapy available(Combivir)	Combivir: one tablet twice daily	Combivir: tablets containing 300 mg zidovudine and 150 mg lamivudine
Zidovudine plus emtricitabine (Emtriva)	Zidovudine: 300 mg twice daily or 200 mg three times daily, with food	Zidovudine: see above	Zidovudine: see above	Zidovudine: see above
	Emtricitabine: 200 mg daily	Emtricitabine: 200-mg capsules	Emtricitabine: once-daily dosing; well tolerated; long intracellular half-life (40 hours); tolerability and virologic response rates appear better than regimens containing didanosine (Videx) plus stavudine (Zerit).	Emtricitabine: rash may be more common than with lamivudine; cross-resistance with lamivudine; hyperpigmentation possible with long-term use in nonwhites.
Tenofovir (Viread) plus lamivudine	Tenofovir: 300 mg daily*	Tenofovir: 300-mg tablets	Tenofovir: once-daily dosing; resistance profile activity against certain thymidine analogue mutations; well tolerated	Tenofovir: same class warnings as nucleoside reverse transcriptase inhibitors; drug interactions; increased drug concentrations in persons taking atazanavir (Reyataz) and lopinavir/ritonavir (Kaletra); must monitor patients for toxicity.
	Lamivudine: 300 mg daily or 150 mg twice daily	Lamivudine: see above	Lamivudine: see above
Tenofovir plus emtricitabine	Tenofovir: 300 mg daily*	Tenofovir: see above	Tenofovir: see above	Tenofovir: see above
	Emtricitabine: 200 mg daily	Emtricitabine: see above	Emtricitabine: see above	Emtricitabine: see above
Combination therapy available (Truvada)	Truvada: one tablet daily*	Truvada: tablets containing 300 mg tenofovir and 200 mg emtricitabine
Basic regimens (alternate)
Lamivudine plus stavudine	Lamivudine: 300 mg daily or 150 mg twice daily	Lamivudine: see above	Lamivudine: see above	Potential source virus resistance; potential for delayed toxicity unknown.
	Stavudine: 40 mg twice daily†; 30 mg twice daily in patients weighing less than 60 kg (132 lb)	Stavudine: 15-, 20-, 30-, and 40-mg tablets	Stavudine: GI side effects are rare
Emtricitabine plus stavudine	Emtricitabine: 200 mg daily	Emtricitabine: see above	Emtricitabine: see above	Potential source virus resistance; potential for delayed toxicity unknown.
	Stavudine: 40 mg twice daily†; 30 mg twice daily in patients weighing less than 60 kg	Stavudine: see above	Stavudine: see above
Lamivudine plus didanosine	Lamivudine: 300 mg daily or 150 mg twice daily	Lamivudine: see above	Lamivudine: see above	Diarrhea more common with buffered preparation; associated with toxicity (i.e., peripheral neuropathy, pancreatitis, and lactic acidosis); must be taken on an empty stomach except when taken with tenofovir; drug interactions.
	Didanosine: 400 mg daily or 200 mg twice daily‡; 125 mg twice daily or 250 mg daily in patients weighing less than 60 kg	Didanosine: 25-, 50-, 100-, 150-, and 200-mg buffered tablets	Didanosine: once daily dosing
Emtricitabine plus didanosine	Emtricitabine: 200 mg daily	Emtricitabine: see above	Emtricitabine: see above	Emtricitabine: see above
	Didanosine: 400 mg daily or 200 mg twice daily‡; 125 mg twice daily or 250 mg daily in patients weighing less than 60 kg	Didanosine: see above	Didanosine: see above	Didanosine: see above
Expanded regimen (preferred)
Basic regimen plus lopinavir/ritonavir	Three capsules twice daily	Capsules containing 133 mg lopinavir and 33 mg ritonavir	Potent HIV protease inhibitor; generally well tolerated	Potential for serious or life-threatening drug interactions; may accelerate clearance of certain drugs, including OCPs (requiring additional or alternate contraceptive methods); may cause severe hyperlipidemia, especially hypertriglyceridemia; GI side effects common.
Expanded regimens (alternate)
Basic regimen plus one of the following drugs:
Atazanavir with or without ritonavir (Norvir)	Atazanavir alone: 400 mg daily*	Atazanavir: 100-, 150-, and 200-mg capsules	Potent HIV protease inhibitor; once-daily dosing; generally well tolerated	Hyperbilirubinemia and jaundice common; potential for serious or life- threatening drug interactions; must avoid coadministration with proton pump inhibitors; administration of antacids and buffered medications must be separated by two hours and histamine H2 antagonists by 12 hours to avoid decreasing atazanavir levels; caution must be used with products known to cause PR prolongation (e.g., diltiazem [Cardizem]).
		Ritonavir: 100-mg capsules
Fosamprenavir (Lexiva) with or without ritonavir	Fosamprenavir alone: 1,400 mg twice daily	Fosamprenavir: 700-mg capsules	Once-daily dosing when taken with ritonavir	GI side effects common; multiple drug interactions; OCPs decrease fosamprenavir concentrations; incidence of rash in healthy volunteers, especially when used with low doses of ritonavir; differentiating between early drug-associated rash and acute seroconversion may be difficult.
	With ritonavir: 1,400 mg fosamprenavir daily plus 200 mg ritonavir daily, or 700 mg fosamprenavir twice daily plus 100 mg ritonavir twice daily	Ritonavir: see above
Indinavir (Crixivan) with or without ritonavir	Indinavir: 800 mg twice daily	Indinavir: 200-, 333-, and 400-mg capsules	Potent HIV inhibitor	Potential for serious or life-threatening drug interactions; serious toxicity possible; consumption of eight glasses of water daily is required; hyperbilirubinemia is common; requires acid for absorption and cannot be taken simultaneously with didanosine.
	Ritonavir: 100 mg twice daily	Ritonavir: see above
Saquinavir (Invirase) plus ritonavir	Saquinavir: 1,000 mg twice daily	Saquinavir: 200-mg capsules	Generally well tolerated, although GI events are common.	Potential for serious or life-threatening drug interactions; substantial pill burden
	Ritonavir: 100 mg twice daily	Ritonavir: see above
Nelfinavir (Viracept)	1,250 mg twice daily with meals	250- and 625-mg tablets	Generally well tolerated	Diarrhea and other GI side effects common; potential for serious or life-threatening drug interactions; substantial pill burden
Efavirenz (Sustiva)	600 mg daily at bedtime	50-, 100-, and 200-mg capsules and 600-mg tablets	Once-daily dosing; does not require phosphorylation before activation; may be active earlier than other agents	Associated with rash that may progress to Stevens-Johnson syndrome; differentiating between early drug-associated rash and acute seroconversion can be difficult; CNS side effects; teratogenic; potential for serious or life-threatening drug interactions.