EFAVIRENZ

EFAVIRENZ
(e-fa'vi-renz)
Sustiva
Classifications: antiretroviral agent; nonnucleoside reverse transcriptase inhibitor (nnrti);
Therapeutic:antiretroviral
; nnrti
Pregnancy Category: D

Availability

50 mg, 100 mg, 200 mg capsules; 300 mg, 600 mg tablets

Action

Nonnucleoside reverse transcriptase inhibitor (NNRTI) of HIV-1. Binds directly to reverse transcriptase and blocks RNA polymerase activities of the HIV-1 virus, thus preventing replication of the virus.

Therapeutic Effect

Prevents replication of the HIV-1 virus. HIV-2 reverse transcriptase and DNA polymerases alpha, beta, gamma, and delta are not inhibited by efavirenz. Resistant strains appear rapidly. Effectiveness is indicated by reduction in viral load (plasma level HIV RNA).

Uses

HIV-1 infection in combination with other antiretroviral agents.

Contraindications

Hypersensitivity to efavirenz; pregnancy (category D), lactation.

Cautious Use

Liver disease, alcoholism, hepatitis, hypertriglyceridemia, hypercholesterolemia, substance abuse, antimicrobial resistance, bipolar disorder, depression, suicidal ideation, exfoliative dermatitis; females of childbearing age, CNS disorders; history of seizures. Safety and efficacy in children <3 y old or who weigh <13 kg (29 lb) are not known.

Route & Dosage

HIV Infection
Adult: PO 600 mg q.d.
Child: PO ≥3 y, 10–15 kg, 200 mg q.d.; 15–20 kg, 250 mg q.d.; 20–25 kg, 300 mg q.d.; 25–32.5 kg, 350 mg q.d.; 32.5–40 kg, 400 mg q.d.; >40 kg, 600 mg q.d.

Administration

Oral
  • Use bedtime dosing to increase tolerability of CNS adverse effects.
  • Give exactly as ordered. Do not skip a dose or discontinue therapy without consulting the physician.
  • Do not give efavirenz following a high fat meal.
  • Store at 15°–30° C (59°–86° F) in a tightly closed container and protect from light.

Adverse Effects (≥1%)

Body as a Whole: Fatigue, fever. CNS: Dizziness, headache, hypoesthesia, impaired concentration, insomnia, abnormal dreams, somnolence, depression, nervousness, adverse psychiatric experiences. CV: Hypercholesterolemia. GI: Nausea, vomiting, diarrhea, dyspepsia, abdominal pain, flatulence, anorexia, increased liver function tests (ALT, AST). Respiratory: Cough. Skin: Rash (erythematous rash, pruritus, maculopapular rash, erythema multiforme, Stevens-Johnson syndrome, toxic epidermal necrolysis), increased sweating. Urogenital: Renal calculus, hematuria.

Diagnostic Test Interference

False-positive urine tests for marijuana.

Interactions

Drug: Decreased concentrations of clarithromycin, indinavir, nelfinavir, saquinavir, voriconazole; increased concentrations of ritonavir, azithromycin, ethinyl estradiol. Efavirenz levels are increased by ritonavir, fluconazole and decreased by saquinavir, rifampin. Additional drugs not recommended for administration with efavirenz include midazolam, triazolam, ergot derivatives, warfarin. Herbal: St. John's wort may decrease antiretroviral activity.

Pharmacokinetics

Peak: 5 h; steady-state 6–10 d. Distribution: 99% protein bound. Metabolism: In liver by cytochrome P450 3A4 and 2B6; can induce (increase) its own metabolism. Elimination: 14–34% in urine, 16–61% in feces. Half-Life: 52–76 h after single dose, 40–55 h after multiple doses.

Nursing Implications

Assessment & Drug Effects

  • Monitor for suicidal ideation in patients who are depressed, or who have a history of depression.
  • Monitor GI status and evaluate ability to maintain a normal diet.
  • Lab tests: Periodic liver functions and lipid profile.

Patient & Family Education

  • Contact physician promptly if any of the following occurs: skin rash, delusions, inappropriate behavior, thoughts of suicide.
  • Use or add barrier contraception if using hormonal contraceptive.
  • Notify physician immediately if you become pregnant.
  • Do not drive or engage in potentially hazardous activities until response to the drug is known. Dizziness, impaired concentration, and drowsiness usually improve with continued therapy.

Common adverse effects in italic, life-threatening effects underlined; generic names in bold; classifications in SMALL CAPS; Canadian drug name; Prototype drug

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