Abacavir
Mechanism :
Abacavir is a carbocyclic synthetic nucleoside analogue. Abacavir is converted by cellular enzymes to the active metabolite, carbovir triphosphate (CBV-TP), an analogue of deoxyguanosine-5’-triphosphate (dGTP). CBV-TP inhibits the activity of HIV-1 reverse transcriptase (RT) both by competing with the natural substrate dGTP and by its incorporation into viral DNA. Abacavir is also a weak inhibitor of cellular DNA polymerases (alpha, beta, and gamma).
Indication :
Contraindications :
Contraindicated in patients with previously demonstrated hypersensitivity to abacavir or any other component of the products. Patients testing positive for the presence of the HLA-B*5701 allele are at a significantly increased risk for hypersensitivity reactions. Fatal rechallenge reactions have been associated with re-administration of abacavir to patients with a prior history of a hypersensitivity reaction to abacavir. Contraindicated in patients with moderate or severe hepatic impairment.
Dosing :
>3 months-18 years:
8 mg/kg BDS OR 16 mg/kg per day. Max: 300 mg BDS.
Adverse Effect :
Fever/chills, redistribution/accumulation of body fat, lactic acidosis, hepatic steatosis, rash, Stevens-Johnson syndrome (SJS) and toxic epidermal necrolysis (TEN), erythema multiforme, insomnia, headache, malaise, fatigue, anxiety, depression, hyperglycemia, hypertriglyceridemia, nausea, vomiting, diarrhea, anorexia; pancreatitis (rare), asthenia, musculoskeletal pain, cough, thrombocytopenia, hypersensitivity reaction.
Interaction :
Ethanol: Decreases the elimination of abacavir causing an increase in overall exposure.
Ganciclovir-Valganciclovir: May enhance the adverse/toxic effect of Reverse Transcriptase Inhibitors (Nucleoside). Hematologic toxicity is of specific concern.
Protease Inhibitors: May decrease the serum concentration of Abacavir.
Ribavirin: May enhance the hepatotoxic effect of Reverse Transcriptase Inhibitors (Nucleoside). Lactic acidosis may occur.
Renal Dose :
Dose in Renal Impairment GFR (mL/min)
| 20-50 | Dose as in normal renal function |
| 10-20 | Dose as in normal renal function |
| <10 | Dose as in normal renal function |
Dose in Patients undergoing Renal Replacement Therapies
| CAPD | Unknown dialysability. Dose as in normal renal function |
| HD | Unlikely to be dialysed. Dose as in normal renal function |
| HDF/High flux | Not dialysed. Dose as in normal renal function |
| CAV/VVHD | Unknown dialysability. Dose as in normal renal function |
Hepatic Dose :
Mild hepatic impairment: Use with caution. Decrease the dose if required.
Moderate to severe hepatic impairment: Avoid using as efficacy and pharmacokinetic parameters are not known.