Abacavir

Ziagen

Classification

Antiretroviral drug; Nucleoside reverse transcriptaze inhibitor (NRTI)

Therapeutic action

Abacavir is a synthetic nucleoside analog and inhibits HIV virus. Mechanism of action – inhibiting  the activity of viral reverse transcriptase (RT). Abacavir prevents the formation of viral DNA replication.

Pregnancy category

C

 

Uses, Indications

Abacavir is used to treat HIV infection in combination with other antiretroviral agents.

Contraindications

• Hypersensitivity to Abacavir
• Lactic acidosis
• Creatinine clearance of less  than 50 mL/min
• Severe hepatomegaly with severe steatosis;
• Moderate to severe hepatic impairment
• Patients with HLA-B*5701 allele ( they are in a high risk group  for hypersensitivity reaction to this drug)
• Lactation

Use cautiously 

• If there is prior resistance to another nucleoside reverse transcriptase inhibitor (NRTI)
• If there is a history of cardiac disease
• With oder adults
• In pregnant women (category C drug )
• Safe use in children younger than 3 months has not been established

Side effects

• Hypersensitivity reactions may occur (may manifest as  fever, skin rash, fatigue, nausea, vomiting, diarrhea, abdominal
  pain); malaise; lethargy; myalgias; arthralgias; paresthesias; edema; shortness of breath.
• Insomnia, headache and fever.
• Hypotension (associated with hypersensitivity reaction), heart attack.
• Hepatomegaly with steatosis, nausea, vomiting, diarrhea, anorexia, pancreatitis, increased GGT, increased liver function tests.
• Metabolic complications, particularly lactic acidosis, renal insufficiency

Administration

Tablets and oral solution of Abacavir are interchangeable on a mg-for-mg basis.
Tablets and liquid  should be stored at 20°– 25° C (68°–77° F). Liquid  form of this drug may be refrigerated.

Pharmacokinetics

 

Bioavailability of drug: It is   83% bioavailable.
Metabolism of drug : It is metabolized by alcohol dehydrogenase and glucuronyl transferase to inactive metabolites.
Elimination of drug : 84% of drug is found in urine, primarily as inactive metabolites;
Half-Life: 1.5 h.

Interactions

Abacavir blood levels may increase with the  use of alcohol.

 

 

Nursing Considerations

Abacavir has been associated with  very serious and sometimes fatal hypersensitivity reactions. This is especially dangerous  to  those patients with the HLA-B*5701 allele. This drug is also associated  with lactic acidosis and severe hepatomegaly, which is sometimes fatal.

Monitor

Patient should be monitored for the signs and symptoms of hypersensitivity, including: fever, skin rash, fatigue, GI distress (nausea, vomiting, diarrhea and  abdominal pain).  In case of hypersensitivity- drug should be withheld.

Patient should be monitored for signs and symptoms of lactic acidosis, renal insufficiency and hepatotoxicity, including:  hyperventilation, lethargy,hepatomegaly, renal insufficiency. If any sign of  acidosis or hepatotoxicity occurs- drug should b withheld.

Monitoring of  lab tests: Prior to first administration screening for HLAB* 5701 should be done. During treatment periodic monitoring of  liver function,  BUN and creatinine, CBC with differential, triglyceride levels,
and blood glucose, especially in diabetics is needed.

Patient and Family education

• This drug should be taken drug exactly as prescribed at indicated times.
• If a dose is missed, then the drug should be taken immediately and the next dose of it should be taken as usual.  The dose should never be doubled.
• At the first sign of  hypersensitivity or liver damage, the drug should be witheld and the doctor should be informed.
• It is recommended that patient should always carry the Warning Card with him at all times.