ritonavir

ritonavir

(ri ton' ah ver)

Norvir

Pregnancy Category B

Drug class

Antiretroviral

Therapeutic actions

Antiviral activity; inhibits HIV protease activity, leading to decrease in production of HIV particles.

Indications

·        Treatment of HIV infection in combination with other antiretrovirals

Contraindications and cautions

·        Contraindicated with allergy to ritonavir.

·        Use cautiously with pregnancy, hepatic impairment, lactation.

Available forms

Capsules—100 mg; oral solution—80 mg/mL

Dosages

ADULTS

600 mg PO bid with food.

PEDIATRIC PATIENTS

Start at 250 mg/m² PO bid and increase by 50 mg/m² twice daily at 2–3 day intervals, to maximum of 400 mg/m² PO bid; do not exceed 600 mg bid. Use in combination with other antiretrovirals.

Pharmacokinetics

Route	Onset	Peak
Oral	Rapid	2–4 hr

Metabolism: Hepatic; T_1/2: 3–5 hr

Distribution: Crosses placenta; may enter breast milk

Excretion: Feces, urine

Adverse effects

·        CNS: Asthenia, peripheral and circumoral paresthesias, anxiety, dreams, headache, dizziness, hallucinations, personality changes

·        CV: Hemorrhage, hypotension, syncope, tachycardia

·        Dermatologic: Acne, dry skin, contact dermatitis, rash

·        GI: Nausea, vomiting, diarrhea, anorexia, abdominal pain, taste perversion, dry mouth, hepatitis, liver dysfunction, dehydration

·        GU: Dysuria, hematuria, nocturia, pyelonephritis

·        Respiratory: Apnea, dyspnea, cough, rhinitis

·        Other: Hypothermia, chills, back pain, chest pain, edema, cachexia

Interactions

Drug-drug

·        Potentially large increase in serum concentration of amiodarone, bepridil, bupropion, clozapine, ergotamine, flecainide, meperidine, piroxicam, propafenone,propoxyphene, quinidine, rifabutin; potential for serious arrhythmias, seizures, and fatal reactions; do not administer ritonavir with any of these drugs

·        Potentially large increases in serum concentration of these sedatives and hypnotics: Alprazolam, clonazepam, diazepam, estazolam, flurazepam, midazolam,triazolam, zolpidem; extreme sedation and respiratory depression could occur; do not administer ritonavir with any of these drugs

Drug-food

·        Absorption increased by presence of food; taking drug with food is strongly recommended

·        Decreased metabolism and risk of toxic effects if combined with grapefruit juice; avoid this combination

Drug-alternative therapy

·        Decreased effectiveness if taken with St. John’s wort

Nursing considerations

CLINICAL ALERT!

Name confusion has been reported between Retrovir (zidovudine) and ritonavir; use caution.

Assessment

·        History: Allergy to ritonavir, hepatic dysfunction, pregnancy, lactation

·        Physical: T; orientation, reflexes; BP, P, peripheral perfusion; R, adventitious sounds; bowel sounds; skin color, perfusion; LFTs

Interventions

·        Capsules and oral solution should be stored in refrigerator; solution may be refrigerated or left at room temperature if used within 30 days; protect from light and extreme heat.

·        Administer with meals or food to increase absorption.

·        WARNING: Carefully screen drug history to avoid potentially dangerous drug interactions.

Teaching points

·        Take this drug with meals or food; store capsules in refrigerator. Taste of solution may be improved if mixed with chocolate milk, Ensure, or Advera 1 hour before taking. Do not drink grapefruit juice while using this drug.

·        Take the full course of therapy as prescribed; do not take double doses if one is missed; do not change dosage without consulting your health care provider. Always take in combination with your other HIV drugs.

·        This drug does not cure HIV infection; long-term effects are not yet known; continue to take precautions as the risk of transmission is not reduced by this drug.

·        Do not take any other drugs, prescription or over-the-counter, without consulting your health care provider; this drug interacts with many other drugs and serious problems can occur.

·        You may experience these side effects: Nausea, vomiting, loss of appetite, diarrhea, abdominal pain, headache, dizziness, numbness, tingling.

·        Report severe diarrhea, severe nausea, personality changes, changes in color of urine or stool, fever, chills.

Adverse effects in Italic are most common; those in Bold are life-threatening.