Kaletra and Mycobutin

In the database of official manuals used in the service creation an interaction registered by statistical results of studies was found, which can either lead to negative consequences for the patient health or strengthen a mutual positive effect. A doctor should be consulted to address the issue of joint drug administration.

Ritonavir may significantly increase the blood levels of rifabutin. This may increase the risk of serious side effects including low white blood cell count and an eye condition known as uveitis, which causes inflammation and swelling of the middle layer of the eye and can lead to blindness. Talk to your doctor if you have any questions or concerns. Your doctor may already be aware of the interaction, but has determined that this is the best course of treatment for you and has taken appropriate precautions and is monitoring you closely for any potential complications. It is important to tell your doctor about all other medications you use, including vitamins and herbs. Do not stop using any medications without first talking to your doctor.

ADJUST DOSE: Coadministration with ritonavir may significantly increase the plasma concentrations of rifabutin and its pharmacologically active 25-O-desacetyl metabolite. The mechanism is ritonavir inhibition of CYP450 3A4, the isoenzyme responsible for the metabolic clearance of rifabutin and 25-O-desacetylrifabutin. In five healthy volunteers, administration of rifabutin (150 mg once daily) with ritonavir (300 mg twice a day titrated up to 500 mg twice a day) for 10 days increased mean steady-state rifabutin peak plasma concentration (Cmax), systemic exposure (AUC) and trough plasma concentration (Cmin) by approximately 2.5-, 4- and 6-fold, respectively, compared to administration of rifabutin alone. Mean steady-state Cmax, AUC, and Cmin of 25-O-desacetylrifabutin increased by 16-, 35-, and 200-fold, respectively. The combination has been associated with increased risk of rifabutin-related adverse effects such as leukopenia, uveitis, arthralgia, joint disorder, and skin discoloration.

MANAGEMENT: To minimize the risk of rifabutin toxicity, the manufacturers suggest that rifabutin dosage be reduced to 150 mg every other day or three times per week in patients treated with ritonavir. More recently, U.S. HIV treatment guidelines and some infectious disease experts have been recommending a rifabutin dosage of 150 mg once daily or 300 mg three times per week when prescribed with ritonavir-boosted protease inhibitor regimens, as lower dosages of rifabutin have been associated with potentially subtherapeutic plasma levels in some studies. Therapeutic drug monitoring for rifabutin is advisable. Patients should be monitored closely for adverse effects of rifabutin, and a complete blood count should be performed at least weekly and as clinically indicated to monitor for development of neutropenia. Further dosage adjustments should be guided by therapeutic response and patient tolerance.

Kaletra

Generic Name: lopinavir / ritonavir

Brand name: Kaletra

Synonyms: n.a.

What is Kaletra?

Mycobutin

Generic Name: rifabutin

Brand name: Mycobutin

Synonyms: n.a.

What is Mycobutin?