Spotlight on Omalizumab in Allergic Asthma

Omalizumab (Xolair) is a humanized monoclonal antibody used in the treatment of adolescent and adult patients with moderate to severe allergic asthma inadequately controlled with inhaled corticosteroids (ICS). It selectively binds to circulating immunoglobulin E (IgE) and, thereby, prevents binding of IgE to mast cells and other effector cells. Without surface-bound IgE, these cells are unable to recognize allergens, thus preventing cellular activation by antigens and the subsequent allergic/asthmatic symptoms. Omalizumab decreases free serum IgE levels in a dose-dependent manner, reduces IgE receptor density on effector cells, and significantly improves airway inflammation parameters.Omalizumab is slowly absorbed after subcutaneous administration, and mean elimination half-life is 26 days, thus allowing infrequent administration of the drug. Omalizumab dosage is determined by bodyweight and pretreatment serum total IgE levels. Patients treated with subcutaneous omalizumab in clinical trials received a dosage that was approximately equal to 0.016 mg/kg/IgE (IU/mL) per 4 weeks. Thus, patients received 150 or 300 mg every 4 weeks, or 225, 300, or 375 mg every 2 weeks.In adults and adolescents (> or = 12 years of age) with moderate to severe allergic asthma, subcutaneous administration of omalizumab as add-on therapy with ICS improved the number of asthma exacerbations, rescue medication use, asthma symptom scores, and quality-of-life (QOL) scores compared with placebo during 28- and 32-week double-blind trials. In addition, concomitant ICS use was significantly decreased in patients receiving omalizumab, and in the two largest double-blind trials approximately 40% of omalizumab recipients completely withdrew from ICS therapy while maintaining effective asthma control. In general, results of extension studies showed that the beneficial effects of omalizumab were maintained over a total period of 52 weeks. Omalizumab was well tolerated as add-on therapy with ICS during treatment for up to 52 weeks. Common adverse events in clinical trials included injection site reaction, viral infection, upper respiratory tract infection, sinusitis, headache, and pharyngitis, although the incidence of adverse events with omalizumab was similar to that with placebo.In conclusion, omalizumab, as add-on therapy with ICS, is an effective and well tolerated agent for the treatment of moderate to severe allergic asthma in adolescents and adults. In addition to its symptomatic and QOL benefits, omalizumab therapy allows ICS dosage reduction or discontinuation of ICS in many patients. Comparisons of omalizumab with other asthma therapies have yet to be conducted; however, clinical efficacy and tolerability data indicate that omalizumab is a valuable option in the treatment of allergic asthma.     

Fosamprenavir: a review of its use in the management of antiretroviral therapy-naive patients with HIV infection

Fosamprenavir (GW433908, Lexiva, Telzir) is an oral prodrug of the protease inhibitor (PI) amprenavir, with a reduced daily pill burden. Fosamprenavir, in combination with other antiretroviral agents, is indicated for the treatment of patients with HIV infection, particularly those who have not previously received antiretroviral therapy. Viral load reductions were at least as great with fosamprenavir-based regimens as those achieved with nelfinavir-based regimens in two large, 48-week, randomised, multicentre trials in antiretroviral therapy-naive patients with HIV infection. In the NEAT study, more patients receiving twice-daily fosamprenavir in combination with abacavir and lamivudine achieved HIV RNA levels <400 copies/mL than those receiving a similar nelfinavir-based regimen. Results of the SOLO study showed similar reductions in viral load among patients who received once-daily ritonavir-boosted fosamprenavir and those treated with twice-daily nelfinavir, both in combination with twice-daily abacavir and lamivudine. In both trials, virological failure rates were at least twice as high with the nelfinavir-based regimen as they were with the fosamprenavir-based regimen. Fosamprenavir was generally well tolerated in clinical trials. The most common adverse events among patients treated with fosamprenavir, with or without ritonavir, plus abacavir and lamivudine were diarrhoea, nausea, vomiting, abdominal pain, drug hypersensitivity and skin rash. The incidence of diarrhoea was significantly lower with fosamprenavir-based therapy than with nelfinavir-based therapy in the NEAT and SOLO trials. The resistance profile of fosamprenavir is consistent with that of amprenavir. Amprenavir-resistant viral isolates from patients experiencing treatment failure with fosamprenavir-based therapy in the NEAT study showed little or no cross-resistance to several other PIs, and protease mutations commonly selected for by various other PIs were not observed. In the SOLO study, protease resistance mutations were not observed in viral isolates from patients experiencing treatment failure with ritonavir-boosted fosamprenavir-based therapy. In conclusion, fosamprenavir-based regimens have shown good antiviral efficacy and are generally well tolerated in antiretroviral therapy-naive patients with HIV infection. Available data on the resistance profile of the drug suggest that it may be used early in the course of therapy without compromising a range of future treatment options. The relatively low pill burden and lack of food restrictions with fosamprenavir may improve adherence to therapy. Further studies are needed to compare fosamprenavir with other PIs and to establish the long-term efficacy of fosamprenavir-based regimens. In conclusion, fosamprenavir appears to be a promising agent for the treatment of antiretroviral therapy-naive patients with HIV infection.     

Peginterferon-alpha-2a (40kD) plus ribavirin: a review of its use in hepatitis C Virus And HIV co-infection

Pegylated interferon plus ribavirin is the standard first-line treatment in patients with chronic hepatitis C virus (HCV) mono-infection. Although the optimal anti-HCV regimen is not established in the more difficult-to-treat population with HIV-HCV co-infection, much of the data in this clinical setting have been derived from studies evaluating peginterferon-alpha-2a (40kD) [Pegasys] plus ribavirin (Copegus), most notably the APRICOT (AIDS Pegasys Ribavirin International Co-Infection Trial) and the ACTG (AIDS Clinical Trial Group) A5071 study. In particular, results of APRICOT - the largest study conducted to date with a pegylated interferon plus ribavirin in patients with HIV-HCV co-infection - indicate that a substantial proportion of patients will achieve sustained virological response (SVR) at week 72 when these drugs are administered for 48 weeks in an appropriate dosage regimen. In general, the tolerability profile of peginterferon-alpha-2a plus ribavirin in APRICOT was similar to that previously reported in patients with HCV mono-infection.     

Palivizumab: a review of its use as prophylaxis for serious respiratory syncytial virus infection

Palivizumab (Synagi) is a humanized monoclonal antibody that provides immunoprophylaxis against serious lower respiratory tract infections (LRTIs) caused by respiratory syncytial virus (RSV). RSV is the leading cause of hospitalization for LRTIs in infants, causing winter- or wet-season epidemics. In two double-blind, placebo-controlled trials, intramuscular palivizumab 15 mg/kg every 30 days for 5 months significantly reduced RSV-related hospitalizations by 55% in 1502 infants with prematurity and/or bronchopulmonary dysplasia/chronic lung disease (BPD/CLD) and by 45% in 1287 infants with hemodynamically significant congenital heart disease (HSCHD). Reductions were statistically significant versus placebo in infants with BPD/CLD, with all degrees of prematurity, and with acyanotic/other heart disease. Palivizumab was generally well tolerated, with < or =1.9% of recipients discontinuing treatment for tolerability reasons. In placebo-controlled trials, the most common potentially drug-related adverse events were fever, nervousness, injection-site reactions, and diarrhea. Drug-related events occurred in 7.2-11% of palivizumab recipients in controlled trials (vs 6.9-10% with placebo) and 0-7.9% in open-label trials. Very few serious potentially drug-related adverse events occurred in clinical trials; four occurred in 2 of 285 patients in one open-label trial. No significant anti-palivizumab antibodies developed during palivizumab use. Palivizumab trough serum concentrations were below the recommended 40 microg/mL in about 33% and up to 14% of children prior to their second and third palivizumab injections. In pharmacoeconomic studies, the cost of palivizumab per hospitalization averted was generally lowest in the highest-risk infants. Drug cost was generally the most influential factor in sensitivity analyses. In conclusion, prophylaxis with palivizumab significantly reduces the incidence of RSV-related hospitalization relative to placebo and is generally well tolerated in high-risk infants aged <2 years, including those with prematurity and BPD/CLD or HSCHD, which are risk factors for early or serious RSV infection. Palivizumab is approved for use in these patients. Other high-risk infants in whom palivizumab has not been formally assessed, such as those with immunodeficiency, cystic fibrosis, or location-specific risk factors (including extended hospital stays) might potentially benefit from palivizumab. The use of palivizumab in these other high-risk populations is likely to be determined as much by pharmacoeconomic considerations as by efficacy outcomes.     

Olanzapine: an updated review of its use in the management of schizophrenia

Olanzapine, a thienobenzodiazepine derivative, is a second generation (atypical) antipsychotic agent which has proven efficacy against the positive and negative symptoms of schizophrenia. Compared with conventional antipsychotics, it has greater affinity for serotonin 5-HT2A than for dopamine D2 receptors. In large, well controlled trials in patients with schizophrenia or related psychoses, olanzapine 5 to 20 mg/day was significantly superior to haloperidol 5 to 20 mg/day in overall improvements in psychopathology rating scales and in the treatment of depressive and negative symptoms, and was comparable in effects on positive psychotic symptoms. The 1-year risk of relapse (rehospitalisation) was significantly lower with olanzapine than with haloperidol treatment. In the first double-blind comparative study (28-week) of olanzapine and risperidone, olanzapine 10 to 20 mg/day proved to be significantly more effective than risperidone 4 to 12 mg/day in the treatment of negative and depressive symptoms but not on overall psychopathology symptoms. In contrast, preliminary results from an 8-week controlled study suggested risperidone 2 to 6 mg/day was superior to olanzapine 5 to 20 mg/day against positive and anxiety/depressive symptoms (p < 0.05), although consistent with the first study, both agents demonstrated similar efficacy on measures of overall psychopathology. Improvements in general cognitive function seen with olanzapine treatment in a 1-year controlled study of patients with early-phase schizophrenia, were significantly greater than changes seen with either risperidone or haloperidol. However, preliminary results from an 8-week trial showed comparable cognitive enhancing effects of olanzapine and risperidone treatment in patients with schizophrenia or schizoaffective disorder. Several studies indicate that olanzapine has benefits against symptoms of aggression and agitation, while other studies strongly support the effectiveness of olanzapine in the treatment of depressive symptomatology. Olanzapine is associated with significantly fewer extrapyramidal symptoms than haloperidol and risperidone. In addition, olanzapine is not associated with a risk of agranulocytosis as seen with clozapine or clinically significant hyperprolactinaemia as seen with risperidone or prolongation of the QT interval. The most common adverse effects reported with olanzapine are bodyweight gain, somnolence, dizziness, anticholinergic effects (constipation and dry mouth) and transient asymptomatic liver enzyme elevations. In comparison with haloperidol, the adverse events reported significantly more frequently with olanzapine in > or = 3.5% of patients were dry mouth, bodyweight gain and increased appetite and compared with risperidone, only bodyweight gain occurred significantly more frequently with olanzapine. The high acquisition cost of olanzapine is offset by reductions in other treatment costs (inpatient and/or outpatient services) of schizophrenia. Pharmacoeconomic analyses indicate that olanzapine does not significantly increase, and may even decrease, the overall direct treatment costs of schizophrenia, compared with haloperidol. Compared with risperidone, olanzapine has also been reported to decrease overall treatment costs, despite the several-fold higher daily acquisition cost of the drug. Olanzapine treatment improves quality of life in patients with schizophrenia and related psychoses to a greater extent than haloperidol, and to broadly the same extent as risperidone. CONCLUSIONS: Olanzapine demonstrated superior antipsychotic efficacy compared with haloperidol in the treatment of acute phase schizophrenia, and in the treatment of some patients with first-episode or treatment-resistant schizophrenia. The reduced risk of adverse events and therapeutic superiority compared with haloperidol and risperidone in the treatment of negative and depressive symptoms support the choice of olanzapine as a first-line option in the management of schizophrenia in the acute phase and for the maintenance of treatment response.     

Diclofenac/misoprostol. Pharmacoeconomic implications of therapy.

The combined formulation of diclofenac/misoprostol provides effective relief of pain and inflammation, with a 2- to 3-fold lower incidence of NSAID-associated gastroduodenal ulcers than diclofenac monotherapy. Both components of the combined formulation have been widely used and have well documented efficacy and tolerability profiles. Compared with other agents used as prophylaxis for NSAID-induced gastropathies, misoprostol is generally considered to have the most extensive outcomes data establishing its efficacy in preventing both gastric and duodenal ulcers associated with long term NSAID use. Economic analyses conducted to date have shown that diclofenac/misoprostol is associated with similar or lower total direct medical treatment costs compared with other NSAIDs (with or without coprescribed misoprostol or an alternate prophylactic agent). As with pharmacoeconomic studies of coprescribed misoprostol with NSAIDs, the most favourable results with the combined formulation of diclofenac/misoprostol appear to be in patients at high risk of developing NSAID-associated gastroduodenal ulcers (e.g. the elderly). Although economic analyses with diclofenac/misoprostol were conducted in several different countries using a variety of methodologies and employing a wide range of clinical and economic assumptions, results have been generally favourable for the combined formulation. However, as is the case with pharmacoeconomic analyses in general, results of individual studies with diclofenac/misoprostol may not be generalisable between countries and are subject to change over time. Overall, clinical and economic data suggest that the optimal and most cost-effective use of the combined formulation of diclofenac/misoprostol is in patients requiring long term NSAID therapy who are at increased risk of developing NSAID-induced gastropathy, such as elderly patients with rheumatoid arthritis or osteoarthritis.