Combination therapy with indinavir, ritonavir, and delavirdine and nucleoside reverse transcriptase inhibitors in patients with HIV/AIDS who have failed multiple antiretroviral combinations

Synchronizing the release rates of salicylate and indomethacin from degradable chitosan hydrogel and its optimization by definitive screening design

Three types of ionically crosslinked (with citric acid) chitosan discs were loaded with the highly water- soluble drug, sodium salicylate (SS) and the poorly water-soluble drug, indomethacin (Ind). In separate experiments the hydrated discs were immersed in a de-crosslinking solution comprising of different concentrations of calcium chloride, which induced a controlled erosion of the discs, a process which was optimized to synchronize the release rates of the two drugs over a predetermined period of time. The optimization was accomplished by manipulating six factors: chitosan MW, its amount in the formulation, the concentration of the crosslinker agent, the concentration of the de-crosslinking agent in the dissolution medium, its pH and its temperature. A computerized multifactorial definitive screening design analysis assisted in minimizing the number of experiments. The quotient of the SS to Ind release rates, the difference factor f1, the similarity factor f2 and the combination of f1 and f2 were determined as the experimental responses. The computerized prediction profilers that were used to simulate the contribution of the experimental factors and their effect on the experimental responses led to a successful erodible formulation with a concomitant release of the two drugs over 150 min.

Effectiveness of Antiretroviral Therapy after Protease Inhibitor Failure: An Analytic Overview

To examine effectiveness of subsequent antiretroviral therapy (ART), studies published during the period of 1 January 1997 through 31 May 2003 involving patients who had failed a protease inhibitor (PI)-containing regimen and were switched to another regimen were reviewed. Twelve studies describing 1197 patients were analyzed. A total of 38% of patients had human immunodeficiency virus (HIV) RNA levels of <500 copies/mL at 24 weeks. After adjustment for baseline HIV RNA level, the rate of virologic suppression ranged from 16% for patients switching drugs within previously failed classes to 54% for nonnucleoside reverse-transcriptase inhibitor (NNRTI)-naive patients switched to boosted PI- and NNRTI-containing regimens. ART regimens in patients who failed a PI-containing regimen provided virologic suppression only in a few patients. The best response was seen in NNRTI-naive patients receiving NNRTI- and boosted PI-containing regimens. New approaches are needed to achieve better suppression in pretreated HIV-infected patients.

Salvage antiretroviral therapy in HIV infection

Highly-active antiretroviral (ARV) therapy (HAART) has lead to a sharp decline in AIDS-related morbidity and mortality. Treatment failure is a common, significant problem and as many as 50% of patients have detectable plasma HIV RNA despite being on combination ARV therapy. Clinicians must be knowledgeable about the reasons for treatment failure and the best options available for management. Treatment failure can occur because of non-compliance, drug discontinuation, lack of drug potency, inadequate drug plasma concentration and drug resistance. Strategies used when selecting salvage therapy include the use of resistance testing to choose a regimen, the exploitation of pharmacokinetic interactions by boosting protease inhibitor (PI) trough levels and counselling the patient on compliance. When selecting the agents to use in salvage therapy, the new regimen should ideally include as many new agents to which no or minimal resistance is anticipated and at least one new class of drugs if possible. Data on salvage therapy mostly comes from anecdotal reports and retrospective cohort studies. With a paucity of clinical trial data, clinicians are often forced to prescribe unproven regimens based on what is anticipated about cross-resistance and drug interactions. It is important that new agents and new targets continue to be developed as an increasing number of patients in practice have exhausted all treatment options.