Adefovir

INTRODUCTION

Indications

Treatment of chronic hepatitis B in patients with evidence of active viral replication and either evidence of persistently elevated liver function tests or active disease (should be used with lamivudine to ↓ risk of resistance).

Action

Converted to adefovir diphosphate which inhibits viral DNA polymerase (reverse transcriptase). Incorporation into viral DNA causes termination of the DNA chain. Therapeutic Effects: Decreased progression/sequelae of chronic hepatitis B infection.

Adverse Reactions/Side Effects

CNS: headache. Resp: cough, pharyngitis, sinusitis. GI: dyspepsia, HEPATOMEGALY WITH STEATOSIS, abdominal pain, diarrhea, flatulence, increased liver enzymes, nausea, vomiting. GU: hematuria, nephrotoxicity. Derm: pruritus, rash. F and E: LACTIC ACIDOSIS. MS: weakness. Misc: fever, HIV resistance.

PHYSICAL THERAPY IMPLICATIONS

Examination and Evaluation

• Be alert for signs of enlarged, fatty liver (hepatomegaly with steatosis) that can progress to liver dysfunction and liver failure. Signs of liver disease include anorexia, abdominal pain, abdominal swelling (ascites), severe nausea and vomiting, yellow skin or eyes, fever, sore throat, malaise, weakness, facial edema, lethargy, and unusual bleeding or bruising. Notify physician of these signs immediately.

• Monitor signs of lactic acidosis, including confusion, lethargy, stupor, shallow rapid breathing, tachycardia, hypotension, nausea, and vomiting. Notify physician immediately if these signs occur.

• Monitor signs of nephrotoxicity, including blood or pus in urine, decreased urine output, weight gain from fluid retention, and fatigue. Report these signs to the physician.

Interventions

• Always wash hands thoroughly and disinfect equipment (whirlpools, electrotherapeutic devices, treatment tables, and so forth) to help prevent the spread of infection. Employ universal precautions as indicated for specific patients.

• Because of the risk of lactic acidosis, use caution during aerobic exercise and other forms of therapeutic exercise. Assess exercise tolerance frequently (blood pressure, heart rate, fatigue levels), and terminate exercise immediately if any untoward responses occur (See Appendix L).

Patient/Client-Related Instruction

• Instruct patient and family/caregivers to report other troublesome side effects, including severe or prolonged headache, cough, nasopharyngeal inflammation, fever, skin problems (rash, itching), or GI problems (diarrhea, nausea, vomiting, indigestion, loss of appetite, abdominal pain, flatulence).

Pharmacokinetics

Absorption: Rapidly converted from prodrug form (adefovir dipivoxil) to adefovir following oral administration; 59% bioavailable.

Distribution: 0.35–0.39 L/kg.

Metabolism and Excretion: Elimination is primarily renal as unchanged drug.

Half-life: 7.5 hr.

Contraindications/Precautions

Contraindicated in: Hypersensitivity; Lactation: Provide formula or discontinue drug.

Use ...