Raltegravir has been shown to be a potent and safe antiretroviral agent when used at the current FDA-approved dose of 400 mg twice daily. Because raltegravir remains in the blood for a long time (a half-life of approximately 29 hours), researchers conducted a study to see if the drug would be safe and effective at a dose of 800 mg once daily.

This prospective pilot study included 311 HIV patients with viral load < 50 copies/mL who replaced protease inhibitors (PIs) with raltegravir. A total of 125 participants met the inclusion criteria. These patients received raltegravir 800 mg QD (63 patients) or BID (62 patients), according to the schedule of the other drugs in their regimen (QD or BID).

No significant differences were found when comparing baseline characteristics in the 2 groups. Most (81%) were male, the mean age was 47 years, and the median CD4 count was 536 cells/mm3. The most frequent PIs replaced were atazanavir (Reyataz) (n=63) and lopinavir/ritonavir (Kaletra) (n=44).

Clinical, immunological, virological, and laboratory parameters, adherence, and quality of life were analyzed at baseline, at 1 month, and then every 3 months thereafter. Follow-up continued for an average of 35 months.

Results

	5 patients experienced virological failure during follow-up, 1 in the QD arm and 4 in the BID arm (P = 0.74, not a statistically significant difference).
	All 5 who had experienced virological failure using nucleoside/nucleotide reverse transcriptase inhibitors (NRTIs) in the past.
	4 patients discontinued raltegravir: 1 in the QD arm (voluntary withdrawal) and 3 in the BID arm (2 with poor adherence, 1 due to headache).
	No significant differences in laboratory safety parameters were found between the QD and BID during follow-up.
	Adherence was better than 90% in both groups.
	Patients taking raltegravir 800 mg QD showed a trend towards improved quality of life compared with those taking 400 mg BID.

In conclusion, the investigators wrote, "Raltegravir administered QD appears to be as effective and safe as BID, with the benefit of an improved quality of life."

Infectious Diseases Department, Hospital Carlos III, Madrid, Spain.

9/22/09

Reference
A Mena, F Blanco, M Cordoba, and others. A Pilot Study Assessing Raltegravir (Isentress) QD Versus BID in HIV Patients Included in a Simplification Trial. 49th Interscience Conference on Antimicrobial Agents and Chemotherapy (ICAAC 2009). San Francisco. September 12-15, 2009. Abstract H-920.