Ritonavir

Ritonavir tablets are indicated in combination with other antiretroviral agents for the treatment of HIV-1 infection. Ritonavir tablets are HIV protease inhibitors indicated in combination with other antiretroviral agents for the treatment of HIV-1 infection (1)

• Adult patients: 600 mg twice-day with meals Pediatrics patients: The recommended twice daily dose for children greater than one month of age is based on body surface area and should not exceed 600 mg twice daily with meals Ritonavir oral solution should not be administered to neonates before a postmenstrual age (first day of the mother’s last menstrual period to birth plus the time elapsed after birth) of 44 weeks has been attained Ritonavir oral powder can only be used for dosing increments of 100 mg Dose modification for ritonavir tablet is necessary when used with other protease inhibitors General Administration Recommendations Ritonavir tablets must be used in combination with other antiretroviral agents
• Ritonavir tablets are administered orally
• Ritonavir tablets should be swallowed whole, and not chewed, broken or crushed
• Take ritonavir tablets with meals
• General Dosing Guidelines Patients who take the 600 mg twice daily soft gel capsule ritonavir dose may experience more gastrointestinal side effects such as nausea, vomiting, abdominal pain or diarrhea when switching from the soft gel capsule to the tablet formulation because of greater maximum plasma concentration (C max ) achieved with the tablet formulation relative to the soft gel capsule [see Clinical Pharmacology ]
• Patients should also be aware that these adverse events (gastrointestinal or paresthesias) may diminish as therapy is continued. …

Ritonavir tablets USP, 100 mg are white to off-white, film-coated, ovaloid tablets, debossed with ‘Z’ on one side and ‘24’ on other side. Tablet: 100 mg (3)

In HIV-infected patients age greater than 1 month to 21 years, the antiviral activity and adverse event profile seen during clinical trials and through postmarketing experience were similar to that for adult patients.

Clinical studies of ritonavir did not include sufficient numbers of subjects aged 65 and over to determine whether they respond differently from younger subjects. In general, dose selection for an elderly patient should be cautious, usually starting at the low end of the dosing range, reflecting the greater frequency of decreased hepatic, renal or cardiac function, and of concomitant disease or other drug therapy.

• Advise the patient to read the FDA-approved patient labeling (Patient Information) General Administration Information [see Dosage and Administration ]: Advise patients and caregivers to pay special attention to accurate preparation and administration of their dose to minimize the risk of accidental overdose or underdose of ritonavir
• Advise caregivers to inform their healthcare provider if their child’s weight changes in order to make sure that the child’s ritonavir dose is adjusted as needed
• Advise patients to take ritonavir with meals
• For adult patients taking ritonavir tablets, the maximum dose of 600 mg twice daily by mouth with meals should not be exceeded. …

• When co-administering ritonavir tablets with other protease inhibitors, see the full prescribing information for that protease inhibitor including contraindication information
• Ritonavir tablets are contraindicated in patients with known hypersensitivity (e.g., toxic epidermal necrolysis (TEN) or Stevens-Johnson syndrome) to ritonavir or any of its ingredients. …

When co-administering ritonavir with other protease inhibitors (atazanavir, darunavir, fosamprenavir, saquinavir, and tipranavir), see the full prescribing information for that protease inhibitor including important information for drug interactions. Co-administration of ritonavir can alter the concentrations of other drugs. The potential for drug-drug interactions must be considered prior to and during therapy (4 , 5.1 , 7 , 12.3) 7.1 Potential for Ritonavir to Affect Other Drugs Ritonavir is an inhibitor of cytochrome P450 3A (CYP3A) and may increase plasma concentrations of agents that are primarily metabolized by CYP3A. …

The following have been observed in patients receiving ritonavir: The concomitant use of ritonavir and certain other drugs may result in known or potentially significant drug interactions. Consult the full prescribing information prior to and during treatment for potential drug interactions. (5.1 , 7.2) Toxicity in preterm neonates: Ritonavir oral solution should not be used in preterm neonates in the immediate postnatal period because of possible toxicities. A safe and effective dose of ritonavir oral solution in this patient population has not been established (2.4 , 5.2) Hepatotoxicity: Fatalities have occurred. …

The following adverse reactions are discussed in greater detail in other sections of the labeling. Drug Interactions [see Warnings and Precautions (5.1) ] Hepatotoxicity [see Warnings and Precautions (5.3) ] Pancreatitis [see Warnings and Precautions (5.4) ] Allergic Reactions/Hypersensitivity [see Warnings and Precautions (5.5) ] When co-administering ritonavir with other protease inhibitors, see the full prescribing information for that protease inhibitor including adverse reactions. …

8.1 Pregnancy Pregnancy Exposure Registry There is a pregnancy exposure registry that monitors pregnancy outcomes in women exposed to ritonavir during pregnancy. Healthcare providers are encouraged to register patients by calling the Antiretroviral Pregnancy Registry (APR) at 1-800-258-4263. …

Acute Overdosage - Human Overdose Experience Human experience of acute overdose with ritonavir is limited. One patient in clinical trials took ritonavir 1500 mg per day for two days. The patient reported paresthesias which resolved after the dose was decreased. A post-marketing case of renal failure with eosinophilia has been reported with ritonavir overdose. The approximate lethal dose was found to be greater than 20 times the related human dose in rats and 10 times the related human dose in mice. Management of Overdosage Ritonavir oral solution contains ethanol and propylene glycol. …

Take it when you remember, unless it is nearly time for the next dose. Then skip the missed one. Never take two doses at once to make up for it. Check your leaflet, as some medicines are different.