abacavir (ah-back-ah-veer), Ziagen

 Classification

Therapeutic: antiretrovirals

Pharmacologic: nucleoside reverse transcriptase

inhibitors

Indications

Treatment of HIV-1 infection.

Action

Converted inside cells to carbovir triphosphate, its active

metabolite. Carbovir triphosphate inhibits the activity

of HIV-1 reverse transcriptase, which in turn terminates

viral DNA growth. Therapeutic Effects: Slows

the progression of HIV infection and decreases the occurrence

of its sequelae. Increases CD4 cell counts and

decreases viral load.

Pharmacokinetics

Absorption: Rapidly and extensively (83%) absorbed.

Distribution: Distributes into extravascular space

and readily distributes into erythrocytes.

Metabolism and Excretion: Mostly metabolized

by the liver; 1.2% excreted unchanged in urine.

Half-life: 1.5 hr.

TIME/ACTION PROFILE (blood levels)

ROUTE ONSET PEAK DURATION

PO unknown unknown unknown

Contraindications/Precautions

Contraindicated in: Hypersensitivity (rechallenge

may be fatal); Presence of HLA-B*5701 allele; Moderate

to severe hepatic impairment; Concurrent use of

antiretroviral combination products containing abacavir;

Lactation: Breast feeding not recommended for

HIV-infected patients.

Use Cautiously in: Coronary heart disease; OB:

Safety not established; Pedi: Children >=3 mo (safety not

established).

Adverse Reactions/Side Effects

CNS: headache, insomnia. CV: MYOCARDIAL INFARCTION.

GI: HEPATOMEGALY (WITH STEATOSIS), diarrhea,

nausea, vomiting, anorexia. Derm: rashes. F and E:

LACTIC ACIDOSIS. Misc: HYPERSENSITIVITY REACTIONS, fat

redistribution, immune reconstitution syndrome.

Interactions

Drug-Drug: Alcoholqblood levels. Mayqmethadone

metabolism in some patients; slightqin methadone

dosing may be needed.

Route/Dosage

PO (Adults): 300 mg twice daily.

PO (Children >=3 mo): Oral solution—8 mg/kg

twice daily or 16 mg/kg once daily (not to exceed 600

mg/day); Tablets—14–19 kg: 150 mg twice daily or

300 mg once daily; 20–24 kg: 150 mg in AM and 300

mg in PM or 450 mg once daily; 25 kg: 300 mg twice

daily or 600 mg once daily.

Availability (generic available)

Tablets: 300 mg. Oral solution (strawberry/banana

flavor): 20 mg/mL. In combination with: lamivudine

(Epzicom); lamivudine and zidovudine (Trizivir);

lamivudine and dolutegravir (Triumeq). See

Appendix B.