Generic Name: abacavir sulfate

Brand Names: Ziagen

Abacavir sulfate is used to treat HIV, the virus that can cause acquired immunodeficiency syndrome (AIDS). Abacavir sulfate is not a cure for HIV or AIDS.

Abacavir sulfate may also be used for purposes not listed in this medication guide.

Important Information

You should not use abacavir sulfate if you are allergic to it, or if you have ever taken

Abacavir sulfate is an antiviral medication used to treat human immunodeficiency virus (HIV). It is a nucleoside reverse transcriptase inhibitor (NRTI).

Abacavir sulfate is sometimes used in combination with other HIV medications.

Common side effects of abacavir sulfate include headache, tiredness, and nausea. Abacavir sulfate can also cause a serious condition called a hypersensitivity reaction. Symptoms of a hypersensitivity reaction include fever, rash, and body aches. This condition can be fatal if not treated promptly.

You should not take abacavir sulfate if you are allergic to it or to any other ingredient in the medication. Before taking abacavir sulfate, tell your doctor about all other allergies you have.

Pharmacokinetics

The pharmacokinetics of abacavir have been characterized in HIV-infected adults and children 6 years of age and older. Following oral administration of abacavir sulfate 600 mg once daily to fasting adults, maximum concentrations (Cmax) of abacavir occurred at 3 hours (Tmax). The mean (%CV) apparent steady-state volume of distribution was 12.6 L/kg (37%) and the mean (%CV) apparent plasma clearance was 10.4 L/hr/kg (38%).

In a study of 14 HIV-infected children between the ages of 6 and 12 years (including 3 who received abacavir sulfate 300 mg twice daily), the pharmacokinetic parameters of abacavir following administration of a single dose of abacavir sulfate 300 mg were generally similar to those observed in adults.

In another study, 23 HIV-infected adolescents between the ages of 13 and 18 years (including 8 who received abacavir sulfate 600 mg once daily) had AUC values that were comparable to those seen in adults. However, the mean %CV for apparent plasma clearance was higher in adolescents than in adults (%CV = 54% vs. 38%).

In vitro studies indicate that cytochrome P450 3A (CYP3A) isoenzymes are primarily responsible for the metabolism of abacavir. In vitro data also suggest that abacavir is a substrate for p-glycoprotein (P-gp).

Elimination of abacavir is primarily by renal excretion as unchanged; however, since abacavir is not removed by hemodialysis, is no need to adjust the dose in patients with end-stage renal disease.

Drug interactions

Abacavir sulfate is a substrate for the drug transporter P-glycoprotein (P-gp). Drugs that are inhibitors of P-gp may increase the plasma concentration of abacavir and could increase or prolong adverse reactions.

The use of abacavir sulfate with didanosine is not recommended. Data from a clinical trial indicate that the concomitant use of abacavir sulfate 600 mg once daily and didanosine 250 mg once daily results in increased didanosine exposure compared to the use of each nucleoside reverse transcriptase inhibitor (NRTI) alone. In this study, there was an approximate doubling in didanosine AUC and Cmax when these NRTIs were coadministered. The maximum didanosine exposure was seen at approximately 8 hours after the dose when abacavir and didanosine were taken together. There was no significant change in abacavir pharmacokinetics when these NRTIs were coadministered.

Abacavir sulfate should not be used with zidovudine or with stavudine, due to the increased risk of hypersensitivity reactions.

Side effects

The most common side effects of abacavir sulfate include headache, tiredness, and nausea. Abacavir sulfate can also cause a serious condition called a hypersensitivity reaction. Symptoms of a hypersensitivity reaction include fever, rash, and body aches. This condition can be fatal if not treated promptly. You should not take abacavir sulfate if you are allergic to it or to any other ingredient in the medication. Before taking abacavir sulfate, tell your doctor about all other allergies you have. Tell your doctor if you are pregnant or plan to become pregnant. Abacavir sulfate can pass into breast milk and may harm a nursing baby. Do not take this medication without telling your doctor if you are breastfeeding a baby.

If you have any of these conditions, you may need a dose adjustment or special tests to safely take abacavir sulfate:

  • kidney disease
  • liver disease
  • heart disease
  • a history of pancreatitis

if you are taking any other prescription or nonprescription medicine, herbal preparation, or dietary supplement

Some people taking abacavir sulfate to develop a serious condition called lactic acidosis. Lactic acidosis is a build-up of lactic acid in the blood. Lactic acidosis can be fatal. Symptoms of lactic acidosis include abdominal or stomach discomfort, decreased appetite, diarrhea, fast or irregular heartbeat, general feeling of discomfort or illness, muscle pain or tenderness, nausea, and vomiting. If you experience these symptoms, call your doctor immediately.

Abacavir sulfate may cause other side effects. Call your doctor if you have any unusual problems while taking this medication.”

Dosage and Administration

The recommended dose of abacavir sulfate is 600 mg (two 300 mg tablets) once daily. Abacavir sulfate can be taken with or without food.

If you miss a dose of abacavir sulfate, take it as soon as possible. If it is almost time for your next dose, skip the missed dose and go back to your regular dosing schedule. Do not take 2 doses at once.

Overdose

If you think you have taken too much of this medicine contact a poison control center or emergency room at once.

Storage

Store abacavir sulfate at room temperature, between 68 and 77 degrees F (20 and 25 degrees C). Store away from heat, moisture, and light. Do not store in the bathroom. Keep abacavir sulfate out of the reach of children and away from pets.