Prezista- Another new agent for HIV infection

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Company:

Tibotec

Pharmacologic class:

Antiretroviral (protease inhibitor)

Active ingredient:

Darunavir (as ethanolate) 300 mg; tabs.

Indication:

With ritonavir: for treating HIV infection in antiretroviral treatment-experienced adult patients, in combination with other antiretroviral agents.

Pharmacology:

Darunavir works by inhibiting the activity of HIV protease, an enzyme that is necessary for viral replication. It can reduce viral load, but its long-term clinical benefit is unknown. Darunavir levels are “boosted” by the concomitant use of ritonavir, so darunavir should only be used in combination with ritonavir. The presence of specific viral mutations can affect the likelihood of this drug's being effective in a given patient.

Therefore, doing a genotype and/or phenotype analysis of the baseline virus may help determine the susceptibility of the virus to darunavir/ritonavir therapy.

Clinical trials:

Darunavir was approved based on data from two ongoing studies that indicated a reduction in viral load and an increase in CD4+ cell counts in patients given this drug along with an optimized background regimen (OBR), compared with patients treated with an investigator-selected protease inhibitor regimen plus OBR. In a pooled analysis, more than 69% of the patients treated with darunavir/ritonavir were considered virologic responders through week 24, compared with 21% of the comparator group. The median change in CD4+ cells was 92 cells/mm3 for the darunavir/ritonavir group versus 17 cells/mm3 for the comparator group.

Adults:

Take with food. 600 mg twice daily with ritonavir 100 mg twice daily.

Children:

Not recommended.

Contraindications:

Concomitant rifampin, carbamazepine, phenobarbital, phenytoin, ergots, St. John's wort, lovastatin, simvastatin, pimozide, midazolam, triazolam.

Precautions:

Sulfonamide allergy. Hepatic or severe renal impairment. Diabetes. Hemophilia: monitor for spontaneous bleeding. Fat redistribution. Immune reconstitution syndrome. Elderly. Pregnancy (Cat. B). Nursing mothers: not recommended.

Interactions:

See Contraindications. Voriconazole: not recommended. Avoid protease inhibitors other than those studied (lopinavir/ ritonavir, saquinavir; indinavir, atazanavir), dexamethasone, fluticasone. Potentiates trazodone, rifabutin, atorvastatin, pravastatin, sildenafil, vardenafil, tadalafil (reduce their doses).

Potentiates, and is potentiated by, indinavir, ketoconazole, itraconazole. Increases efavirenz levels. Antagonizes sertraline, paroxetine (monitor levels), ethinyl estradiol (use backup contraception). Antagonizes, and antagonized by, other cytochrome P450 3A4 substrates (e.g., carbamazepine, phenobarbital, phenytoin). Antagonized by efavirenz. Monitor antiarrhythmics (e.g., bepridil, systemic lidocaine, quinidine, amiodarone), calcium channel blockers, warfarin, immunosuppressants (e.g., tacrolimus, cyclosporine), methadone (possible opiate withdrawal syndrome). Reduce concomitant clarithromycin dose in renal impairment. Separate dosing of didanosine. Others.

Adverse reactions:

GI upset, constipation, abdominal pain, headache; rash (discontinue if severe), others.

Inform patients:

Prezista does not cure HIV infections or AIDS and does not prevent passing HIV to others.

How supplied:

Tabs—120.

To register pregnant patients exposed to darunavir/ritonavir, call 800.258.4263. For more information, call 609.730.7500 or visit www.tibotec.com

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