Combination Of Protease Inhibitors Research Articles

Proteases Essential for Human Influenza Virus Entry into Cells and Their Inhibitors as Potential Therapeutic Agents

Influenza A virus (IAV) is one of the most common infectious pathogens in humans. Since IVA genome does not have the processing protease for the viral membrane fusion glycoprotein precursors, entry of this virus into cells is determined primarily by host cellular, trypsin-type, processing proteases that proteolytically activate the fusion glycoprotein precursors of IAV. At least five different processing proteases have been identified in the airways of animals and humans. These proteases determine the infectious organ tropism of IAV infection as well as the efficiency of viral multiplication in the airway, and sometimes in the brain. Proteases in the upper respiratory tract are suppressed by secretory leukoprotease inhibitor, and those in the lower respiratory tract are suppressed by pulmonary surfactant which, by adsorption, inhibits the interaction between the proteases and viral membrane proteins. Since protease activities predominate over those of endogenous inhibitory compounds under normal airway conditions, administration of protease inhibitors in the early-stage of infection significantly suppresses viral entry and viral multiplication. Several viral neuraminidase inhibitors are used clinically as anti-influenza virus agents, based on their inhibitory action on viral release from infected cells. Furthermore, protease inhibitors of viral entry could be potentially useful against influenza virus as well as neuraminidase inhibitor-resistant viruses. We also found that ambroxol, a mucolytic and anti-oxidant agent, up-regulates the levels of endogenous protease inhibitory compounds in the airway fluids in early-phase infection, and that clarithromycin, a macrolide antibiotic, increases IgA levels and mucosal immunity through augmentation of interleukin-12 levels in the airway. The combination of neuraminidase inhibitors and protease inhibitors, clarithromycin or ambroxol, could be potentially used as a potent anti-influenza therapy to minimize the emergence of drug-resistant mutant viruses.

Lopinavir plus ritonavir: a novel protease inhibitor combination for HIV infections

Lopinavir is a protease inhibitor (PI) for the treatment of HIV infection that was specifically designed to overcome the shortcomings of earlier agents in this class. It is the only PI coformulated with ritonavir, whose pharmacological boosting effect results in a highly potent, well-tolerated, clinically effective antiretroviral agent with a high genetic barrier to resistance. Lopinavir/ritonavir is a recommended first-line option for antiretroviral-naive patients initiating PI-based therapy, and has an equally important role in the management of treatment-experienced individuals. Its favorable pharmacological and clinical characteristics have recently prompted investigators to explore its potential novel applications in HIV monotherapy and double-boosted regimens.

Long-Term Suppression of HIV Infection: Benefits and Limitations of Current Treatment Options

HIV type 1, a causative agent of AIDS, is a source of worldwide morbidity and mortality. There are an estimated 1 million people in North America currently living with HIV infection, and more than 40,000 new cases occur annually. Before the advent of highly active antiretroviral therapy (HAART), the mortality rate of HIV infection was nearly 100%, and life expectancy was short. However, successful HAART delays the onset of AIDS, allowing patients to live with chronic HIV infection for 20 years or more. HAART usually consists of a combination of protease inhibitors (PIs), nucleoside reverse transcriptase inhibitors (NRTIs), and/or nonnucleoside reverse transcriptase inhibitors (NNRTIs). Although these agents are highly efficacious in delaying the onset of AIDS, their clinical utility is limited by viral resistance, nonadherence to therapy, and drug toxicity. Consequently, multidrug regimens are necessary for successful treatment. Initial NNRTI-based HAART regimens are effective at reducing viral load and boosting CD4(+) cell counts. NNRTI resistance is uncommon, but should it occur, the NNRTI-based therapy needs to be quickly replaced by a PI-based therapy. Triple NRTI-based regimens are recommended only if NNRTI- or PI-based regimens cannot be used. When developing a multidrug regimen, it is also important to select HAART agents with limited adverse effects. Because each HAART agent has its own unique adverse effect profile, selecting a regimen with a favorable profile may be difficult. For example, certain PIs produce adverse metabolic effects that may increase the risk of developing cardiovascular disease. In contrast, NNRTI-based therapies have a different side effect profile. Because each HAART agent has specific limitations, tailoring a regimen to the individual patient is of paramount importance for achieving optimal outcomes.

A Multienzyme Network Functions in Intestinal Protein Digestion by a Platyhelminth Parasite

Proteases frequently function not only as individual enzymes but also in cascades or networks. A notable evolutionary switch occurred in one such protease network that is involved in protein digestion in the intestine. In vertebrates, this is largely the work of trypsin family serine proteases, whereas in invertebrates, cysteine proteases of the papain family and aspartic proteases assume the role. Utilizing a combination of protease class-specific inhibitors and RNA interference, we deconvoluted such a network of major endopeptidases functioning in invertebrate intestinal protein digestion, using the parasitic helminth, Schistosoma mansoni as an experimental model. We show that initial degradation of host blood proteins is ordered, occasionally redundant, and substrate-specific. Although inhibition of parasite cathepsin D had a greater effect on primary cleavage of hemoglobin, inhibition of cathepsin B predominated in albumin degradation. Nevertheless, in both cases, inhibitor combinations were synergistic. An asparaginyl endopeptidase (legumain) also synergized with cathepsin B and L in protein digestion, either by zymogen activation or facilitating substrate cleavage. This protease network operates optimally in acidic pH compartments either in the gut lumen or in vacuoles of the intestinal lining cells. Defining the role of each of these major enzymes now provides a clearer understanding of the function of a complex protease network that is conserved throughout invertebrate evolution. It also provides insights into which of these proteases are logical targets for development of chemotherapy for schistosomiasis, a major global health problem.

Synergistic Interactions of the Antiretroviral Protease Inhibitors Saquinavir and Ritonavir with Chloroquine and Mefloquine against Plasmodium falciparum In Vitro

The antimalarial activity of several antiretroviral protease inhibitor combinations was investigated. Data demonstrate that ritonavir and saquinavir behave synergistically with chloroquine and mefloquine. These data, and interactions with pepstatin-A, E-64, and bestatin, suggest that human immunodeficiency virus protease inhibitors do not target digestive-vacuole plasmepsins.

Novel Robust Hepatitis C Virus Mouse Efficacy Model

The lack of a robust small-animal model for hepatitis C virus (HCV) has hindered the discovery and development of novel drug treatments for HCV infections. We developed a reproducible and easily accessible xenograft mouse efficacy model in which HCV RNA replication is accurately monitored in vivo by real-time, noninvasive whole-body imaging of gamma-irradiated SCID mice implanted with a mouse-adapted luciferase replicon-containing Huh-7 cell line (T7-11). The model was validated by demonstrating that both a small-molecule NS3/4A protease inhibitor (BILN 2061) and human alpha interferon (IFN-alpha) decreased HCV RNA replication and that treatment withdrawal resulted in a rebound in replication, which paralleled clinical outcomes in humans. We further showed that protease inhibitor and IFN-alpha combination therapy was more effective in reducing HCV RNA replication than treatment with each compound alone and supports testing in humans. This robust mouse efficacy model provides a powerful tool for rapid evaluation of potential anti-HCV compounds in vivo as part of aggressive drug discovery efforts.

Placental transfer and pharmacokinetics of lopinavir and other protease inhibitors in combination with nevirapine at delivery

Antiretroviral combination therapies, including nevirapine (NVP) and protease inhibitors (PI), are increasingly used in the treatment and for the prophylaxis of vertical HIV-1 transmission in HIV-1 infected pregnant women. To determine pharmacokinetics and placental transfer of NVP and different PI in pregnancy we measured drug levels in maternal and foetal compartments at the day of delivery. We conducted a prospective study in 40 eligible HIV-1 infected pregnant women who gave birth in our hospital. A pre-dose to 6 h post-dose steady-state pharmacokinetic analysis (n = 35) of the drugs on the day of the scheduled Caesarean section was performed. In addition cord blood and amniotic fluid drug levels were measured (n = 40). In all women NVP plasma concentrations (n = 20) were below the recommended level. PI plasma concentrations (nelfinavir, n = 5; saquinavir, n = 3; lopinavir, n = 10; ritonavir, n = 13) were extremely variable. Cord blood and amniotic fluid drug levels suggested that NVP passes the placenta unrestricted whereas PI were detected in smaller concentrations in the foetal compartment. Because of the changed pharmacokinetics of antiretroviral drugs in pregnancy therapeutic drug monitoring could be important and dose adjustment should be considered. The minimal placental transfer of PI is desirable from the perspective that the foetus is protected from potentially teratogenic agents. However, it is not known if antiretroviral compounds in the foetal compartment contribute to the risk reduction of vertical HIV-1 transmission, and whether the property of missing placental transfer is in fact beneficial for the newborn.

Reactive Pancreatitis Following Endoscopic Retrograde Cholangiopancreatography: Diagnosis, Prevention and Treatment

Objective: to study the risk factors, clinical, laboratory, and functional manifestations, course, prevention, treatment, and outcome of reactive pancreatitis (RP) following endoscopic retrograde cholangiopancreatography (ERCP). Subjects and methods: A study group comprised 207 patients (156 males and 51 females; mean age, 54.5±12.7 years) treated at the N. N. Burdenko Main Military Hospital and undergone ERCP with and without papillosphincterotomy (PST). The patients’ status, the presence and pattern of subjective and objective symptoms and laboratory parameters (blood amylase, urinary diastase, leukocytosis) were dynamically estimated after ERCP. Results: 58 (28.0%) patients developed post-ERCP RP, the severe course of pancreatitis being observed in 4.3%. There were no cases of pancreatic necrosis or fatal outcomes. RP was significantly more common in females, persons under 50 years of age, patients with chronic pancreatitis, cholelithiasis, or major duodenal papillary abnormalities (duodenal papillitis, choledochal stricture), choledocholithiasis, in the absence of the dilated common bile duct. RP less frequently occurred in patients only when adequate or combined PST had been performed. RP was characterized by an acute course, with a significant pain syndrome occurring, by altered health status, fever, hyperamylasemia, and leukocytosis within the first-second days following ERCP, and delayed urinary diastase elevation. Just after ERCP, all the patients were given a combination of octreotide and a protease inhibitor to prevent RP. The efficiency of prevention was directly confirmed by the fact that there were no cases of pancreatic necrosis and fatal outcomes. To treat RP, the authors gave a combination of antisecretory agents, protease inhibitors (contrycal, ingitril), antibacterial drugs (cephalosporins, fluoroquinolones), and proton pump inhibitors during starvation, in the use of analgesics and spasmolytics, and during active infusion therapy. In all cases RP was benign and ended with the patients recovery 5—14 days after initiation of the therapy. Conclusion: ERCP is a serious endoscopic operation characterized by a high risk of life-threatening complications (first of all RP). Before ERCP, the risk factors of RP should be assessed. All patients to undergo ERCP need a complex RP prevention including endoscopy, drugs, and intensive monitoring. In evolving RP, early multimodality therapy comprising antisecretory drugs, protease inhibitors, antibiotic therapy, analgesia, infusion therapy, and starvation.

Concomitant Use of an Active Boosted Protease Inhibitor with Enfuvirtide in Treatment-Experienced, HIV-Infected Individuals: Recent Data and Consensus Recommendations

Recent data from clinical trials investigating the efficacy of enfuvirtide, a fusion inhibitor, in treatment-experienced patients have revealed that the addition of enfuvirtide (ENF) to an active boosted protease inhibitor regimen doubles the rate of virological response. At week 48 of the TORO studies, 55% of patients previously naive to and receiving lopinavir/ritonavir (LPV/r) with ENF achieved a viral load of <400 copies/mL compared with 24% of patients treated with LPV/r alone. At week 24 of the RESIST studies, 70% of previously ENF-naive patients who took both ENF and tipranavir/ritonavir (TPV/r) achieved a ≥1 log10 reduction in viral load compared with 37% of such patients treated with TPV/r alone. Similarly, concomitant use of TMC114/ritonavir (TMC114/r) with ENF, compared with TMC114/r alone, increased the number of patients with <50 copies/mL from 46% to 64% in a combined 24-week analysis from the POWER trials. Data from these trials suggest that combining one agent from a new class with a new agent from a previously exposed class offers a greater chance of achieving full virological control than either type of agent alone. Undetectable viraemia should be the primary objective for treatment-experienced patients requiring a switch in therapy, and the present data support the combination of an active boosted protease inhibitor with an agent from a new class (e.g., ENF) for triple-class-experienced patients.

Concomitant Use of an Active Boosted Protease Inhibitor with Enfuvirtide in Treatment-Experienced, HIV-Infected Individuals: Recent Data and Consensus Recommendations

Recent data from clinical trials investigating the efficacy of enfuvirtide, a fusion inhibitor, in treatment-experienced patients have revealed that the addition of enfuvirtide (ENF) to an active boosted protease inhibitor regimen doubles the rate of virological response. At week 48 of the TORO studies, 55% of patients previously naive to and receiving lopinavir/ritonavir (LPV/r) with ENF achieved a viral load of <400 copies/mL compared with 24% of patients treated with LPV/r alone. At week 24 of the RESIST studies, 70% of previously ENF-naive patients who took both ENF and tipranavir/ritonavir (TPV/r) achieved a ≥1 log10 reduction in viral load compared with 37% of such patients treated with TPV/r alone. Similarly, concomitant use of TMC114/ritonavir (TMC114/r) with ENF, compared with TMC114/r alone, increased the number of patients with <50 copies/mL from 46% to 64% in a combined 24-week analysis from the POWER trials. Data from these trials suggest that combining one agent from a new class with a new agent from a previously exposed class offers a greater chance of achieving full virological control than either type of agent alone. Undetectable viraemia should be the primary objective for treatment-experienced patients requiring a switch in therapy, and the present data support the combination of an active boosted protease inhibitor with an agent from a new class (e.g., ENF) for triple-class-experienced patients.

Partial Treatment Interruption of Protease Inhibitor-Based Highly Active Antiretroviral Therapy Regimens in HIV-Infected Children

Treatment guidelines for HIV-infected children recommend using combinations of reverse transcriptase inhibitors (RTIs) and protease inhibitors (PIs). Successful suppression of HIV replication and adherence to these regimens are often suboptimal because of multiple factors. For patients with detectable viremia and limited treatment options, therapy simplification consisting of RTIs, referred to as partial treatment interruption (PTI), may represent a temporizing option. We describe a cohort of 26 HIV-infected children who underwent treatment simplification by discontinuing the PI and continuing therapy with 2 or more RTIs. The subjects, who were identified retrospectively, were followed for a period of 24 to 96 weeks. Data collected included clinical information, viral load, and CD4T lymphocyte percentage (CD4%) at baseline and 24, 48, and 96 weeks after PTI. Twenty-six, 21, and 11 patients were evaluated at 24, 48, and 96 weeks, respectively. No child had Centers for Disease Control and Prevention-defined disease progression, and there were no significant changes in viral loads (P > 0.5) across all study intervals after interruption of the PIs. Although most children maintained a CD4% > 15%, comparisons of CD4% at 24 and 48 weeks demonstrated a statistically significant decrease compared with baseline. Therapy simplification by PTI may provide a practical option in patients intolerant of or failing PI-based highly active antiretroviral therapy.

Lack of effect of motivation on the adherence of HIV-positive/AIDS patients to antiretroviral treatment

As a result of the potent drug combinations of reverse transcriptase inhibitors and protease inhibitors currently available, it is now possible to achieve extreme reductions in the numbers of viral particles in the peripheral blood of HIV-positive patients undergoing treatment, to the point that they are undetectable. Moreover, the immunological recovery resulting from continued and prolonged use of these drugs significantly reduces both mortality and the incidence of opportunistic infections. However, the strict therapeutic regimens required, the number of pills, adverse events and the stigma of a disease that requires the patient to introduce pill-taking into his/her lifestyle brings into question one aspect of mental health, which is motivation to do that which is being proposed. We investigated the influence of each of the components of the adherence trilogy: information, motivation and behavioral abilities, as risk factors in a population of HIV-positive/AIDS patients undergoing antiretroviral treatment in the city of Salvador, Bahia, Brazil. An intervention study was carried out by introducing motivational assistance into the routine recommendations for the treatment of patients who were initiating antiretroviral (ARV) therapy. Seventy-six treatment-naive patients, who had been selected to initiate ARV therapy, were included. These patients were divided into two groups. Group A, in which the regular routine of the institution was followed, received information on the disease and its treatment;patients in group B had the same routine, but they were also followed-up fortnightly and given motivational intervention. Evaluations of viral load and CD4 count before and following treatment were used to measure adherence. There was no significant difference between the two groups. As the rates of non-adhesion were at the lower limits of the ranges reported in the literature, it would appear that providing motivation and information can be of help to the patient.

Pharmacokinetics and 24-Week Efficacy/Safety of Dual Boosted Saquinavir/Lopinavir/Ritonavir in Nucleoside-Pretreated Children

To assess the pharmacokinetics and 24-week efficacy and safety of dual boosted saquinavir/lopinavir/ritonavir combination in children. Twenty reverse transcription inhibitor-pretreated children at 2 centers in Thailand were treated with saquinavir/lopinavir/ritonavir in an open label, single arm, 6-month prospective study. The dosage was 50 mg/kg twice daily (bid) for saquinavir and 230/57.5 mg/m bid for lopinavir/ritonavir. Ten children also received lamivudine. Samples were collected for a 12-hour pharmacokinetic profile in all children. Plasma concentrations of saquinavir, lopinavir and ritonavir were determined using a validated high performance liquid chromatography technique. At baseline, the median age was 8.5 years, with human immunodeficiency virus (HIV) RNA 4.9 log10 copies/mL, CD4 count 129 cells/microL and CD4%, 6.5%. Median area under the concentration curve at 0-12 hours and Cmin were 39.4 mg/L.h and 1.4 mg/L for saquinavir and 118 mg/L.hr and 5.9 mg/L for lopinavir. After 24 weeks of treatment, HIV RNA was suppressed below 400 copies/mL for 16 of 20 (80%) children (intent-to-treat analysis) and below 50 copies/mL for 12 of 20 children (60%), and CD4% (count) rose by a median of 6% (216 cells/microL). Median changes of triglyceride and total cholesterol were 56 and 36.5 mg/dL, respectively (P = 0.01). Lopinavir Cmin <1 and saquinavir Cmin <0.28 mg/L correlated with HIV RNA >400 copies/mL, and lopinavir Cmax >15 mg/L correlated with rises in cholesterol (P < 0.05). Plasma drug concentrations of saquinavir, lopinavir and ritonavir were at the higher limits of expected ranges for adult treatment at approved dosages (1000/100 mg bid for saquinavir, 400/100 mg bid for lopinavir/ritonavir). The regimen was well-tolerated and had good efficacy at 24 weeks. This dual boosted protease inhibitor combination should be assessed in larger trials of reverse transcription inhibitor-experienced children.

Acute Pancreatitis Associated with Different Combination Therapies in Patients Infected with Human Immunodeficiency Virus

To assess the risk of acute pancreatitis in patients receiving various combinations of protease inhibitors, nucleoside reverse transcriptase inhibitors (NRTIs), and nonnucleoside reverse transcriptase inhibitors (NNRTIs) for treatment of human immunodeficiency virus (HIV) infection. Retrospective cohort study. Ohio Medicaid claims database, January 1997-December 2002. Four thousand nine hundred seventy-two patients with HIV infection who had received at least one antiretroviral drug. Three combination regimens were evaluated: didanosine plus other antiretroviral agents, protease inhibitors plus NRTIs or NNRTIs, and NRTI combinations (no didanosine) or NRTIs plus NNRTIs. We used Cox proportional hazard regression and Kaplan-Meier plots to examine the risk for acute pancreatitis. We identified 159 (3.2%) cases of acute pancreatitis during the study period. For patients who were newly treated for HIV, the incidence of acute pancreatitis was 1.95/100 person-years. Half of these cases developed within 500 days of the start of drug therapy. Hazard ratios (HRs) for acute pancreatitis were 39-54% higher for nonwhite patients than Caucasians and 240-290% higher for symptomatic versus nonsymptomatic patients. Hazard ratios also were significantly associated with increased age, liver injuries (HR 2.94, 6.73), and cardiovascular diseases (HR 1.68, 2.36), respectively, for both newly treated and previously diagnosed patients with HIV. The risk for patients receiving either protease inhibitors plus an NRTI or an NNRTI, or NRTI plus NNRTI combinations was not significantly different from the risk associated with didanosine combination therapy (p>0.10). The risk of acute pancreatitis was significantly associated with age, race, symptomatic HIV infection, and liver and cardiovascular diseases. However, risk did not differ significantly among patients with different antiretroviral regimens. Our results can be used by the medical community to enhance patient safety and minimize costly adverse drug reactions among patients with HIV infection.

Steady-state pharmacokinetics of atazanavir given alone or in combination with saquinavir hard-gel capsules or amprenavir in HIV-1-infected patients

The aim of this pilot study was to examine the pharmacokinetics of atazanavir (ATV) when given in combination with amprenavir (APV) or saquinavir hard-gel capsules (SQV) to human immunodeficiency virus (HIV)-positive patients. Included in the study were 34 HIV-infected patients enrolled in the ATV Early Access Program, who were treated with unboosted ATV alone (group 1) or with the double protease inhibitor combinations, ATV plus APV (group 2) or ATV plus SQV (group 3). ATV was given at a daily dose of 400 mg q.d. with the morning meal with SQV 1200 mg per day or APV 1200 mg per day. Serial blood samples for steady-state ATV pharmacokinetics were collected before the morning dose and at 1, 2, 3, 6, 8 and 24 h post-dosing. ATV plasma concentrations were measured using a high-performance liquid chromatography method with ultraviolet detection. Of the patients, 12 received ATV as a single protease inhibitor; 12 received ATV in combination with APV; and 10 in combination with SQV. Geometric mean (coefficient of variation) ATV C(trough) was 110 ng/ml (2.38), 86 ng/ml (0.84) and 149 ng/ml (2.01) in groups 1, 2 and 3, respectively. ATV C(trough) in both double protease inhibitor combination regimens was not significantly different from that as a single protease inhibitor [geometric mean ratio (GMR): 0.77; 95% confidence interval (CI): 0.38-1.58, P=not significant for group 2 versus group 1 and 1.34, 0.40-4.49, P=not significant, for group 3 versus group 1). Patients treated with ATV plus APV had a 40.2% lower ATV C(max) and a 30.8% smaller ATV AUC than the reference group treated with unboosted ATV alone: both these differences were statistically significant (GMR, 95% CI: 0.59, 0.41-0.85, P=0.005 and 0.69, 0.48-0.99, P=0.056, respectively). No difference was observed for either C(max) or AUC between the group treated with ATV plus SQV and the reference group (GMR, 95% CI: 0.78, 0.47-1.30, P=not significant and 1.24, 0.73-2.10, P=not significant, respectively). ATV pharmacokinetics does not seem to be influenced by the concomitant administration of SQV, whereas APV significantly lowers plasma ATV levels.

Insertions in the Human Immunodeficiency Virus Type 1 Protease and Reverse Transcriptase Genes: Clinical Impact and Molecular Mechanisms

Treatment of human immunodeficiency virus (HIV) type 1 (HIV-1)-infected individuals with antiretroviral (ARV) drugs is highly effective in inhibiting viral replication, increasing both the duration and the quality of life (71). Regimens consisting of combinations of protease (PR), reverse transcriptase (RT), and fusion inhibitors are the current standard of care and typically reduce the circulating virus levels in previously untreated patients to below current limits of detection. Treatment failure, however, is not uncommon and is typically defined as a return to detectable levels of circulating virus, eventually resulting in decreases of CD4-cell counts and immune function and progression to AIDS. The development of viral resistance to ARV drugs is a primary cause of treatment failure (24). Extensive genetic diversity is inherent in HIV because the highly error-prone RT enzyme creates a population of variants from which drug-resistant strains can be selected during treatment (49). Many individual point mutations (single amino acid changes) or groups of point mutations in the PR, RT, or gp41 gene have been associated in clinical studies with the failure of treatment with protease inhibitors (PIs), nucleoside reverse transcriptase inhibitors (NRTIs) and nonnucleoside reverse transcriptase inhibitors (NNRTIs), and fusion inhibitors, respectively (17, 24, 50, 52). HIV-1 strains isolated both from patients who have failed treatment and from laboratory strains modified by site-directed mutagenesis to possess specific mutations show reduced susceptibilities in vitro to one or more ARV drugs. Some point mutations are specific to individual drugs, while others confer cross-resistance to one or more drugs of the same class. Over the past several years, strains with insertions of nucleotides in the PR and the RT genes (and that thus have extra amino acids in those proteins) have been found in patients who have failed ARV drug therapy. Numerous publications have examined the origins, prevalences, in vitro susceptibilities, and replication capacities of insert-containing strains, as well as the mechanisms by which the insertions affect drug resistance. This minireview focuses on the clinically related information regarding PR and RT insert-containing strains of HIV and briefly addresses the topics of mechanism and structure.

The urological management of the patient with acquired immunodeficiency syndrome

In people infected with the human immunodeficiency virus (HIV) both the CD4 T-cell count and the viral load are used to monitor disease progression to acquired immunodeficiency syndrome (AIDS). CD4 counts of <500/mm(3) are associated with opportunistic infections and certain malignancies, so-called 'AIDS-defining' conditions. Highly active antiretroviral therapy, using combinations of reverse transcriptase inhibitors and/or protease inhibitors, can improve considerably the prognosis of people who are HIV-positive, but such therapy is not yet widely available in many developing countries. People with AIDS are predisposed to urinary tract infection (UTI) by uncommon bacteria and pathogens, e.g. fungi, parasites and viruses, which may affect any urogenital organ; treatment should be culture-specific and long-term, because there is a tendency to recurrence, infection with multiple organisms and resistant isolates. Voiding dysfunction in patients with AIDS is usually a result of neurological complications caused by opportunistic infections, and has a poor prognosis. Of patients with AIDS, 30-50% develop a cancer, especially Kaposi's sarcoma (KS) and non-Hodgkin's lymphoma (NHL). KS may involve any urogenital organ, but is usually part of systemic disease. Small lesions on the external genitalia can be treated with laser, cryotherapy or surgical excision, larger lesions with radiotherapy, and disseminated or visceral KS with multidrug chemotherapy. NHL may involve the kidneys, testes and retroperitoneal lymph nodes, thus obstructing the ureters, which may require ureteric stenting or percutaneous nephrostomy. NHL can be treated with radiotherapy and combination chemotherapy. Urolithiasis in patients with AIDS may be caused by indinavir, a protease inhibitor, but the more common types of stones may also occur. Fluid-electrolyte and acid-base disturbances are common in patients with advanced AIDS, secondary to vomiting, diarrhoea, malnutrition or septicaemia. HIV-associated nephropathy occurs in 10-30% of patients, and often leads to renal failure. Testicular atrophy is common, leading to infertility, erectile dysfunction (ED) and decreased libido. Treatment for ED must include counselling about strategies to reduce the transmission of HIV. The risk of HIV transmission after parenteral exposure to blood from an HIV-positive patient is relatively low (0.2-0.4%); the urologist can reduce the risk of transmission during surgery by adopting certain precautions. After occupational exposure to HIV, chemoprophylaxis with antiretroviral medication can significantly reduce the probability of HIV transmission.

Successful desensitization of enfuvirtide-induced skin hypersensitivity reaction

Successful desensitization of enfuvirtide-induced skin hypersensitivity reaction

The pharmacokinetics of HIV protease inhibitor combinations

The clinical use of double-boosted protease inhibitor regimens has evolved recently. This strategy offers a number of unique benefits, including pharmacokinetic enhancement of two different protease inhibitors with low dose ritonavir. We review the pharmacologic rationale for the double-boosted protease inhibitor combinations and the complex drug-drug interactions that occur among different protease inhibitors when co-administered. The discovery and widespread clinical use of low dose ritonavir as a pharmacoenhancer of other protease inhibitors has significantly improved the management of HIV infection treatment. This has subsequently led to the development of double-boosted protease inhibitor regimens which have been shown to be effective in heavily pre-treated patients, in whom it is crucial to maintain drug concentrations sufficient to suppress viruses with multiple resistance mutations. Interesting pharmacokinetic data have been recently produced showing the complexity of the interactions among three protease inhibitors. As the outcome of these multidrug interactions may be difficult to predict, formal pharmacokinetic studies have been fundamental to determine which protease inhibitors are best to administer in combination. This review summarizes the current literature regarding the pharmacokinetics of double-boosted protease inhibitor regimens and general considerations regarding their usage in the treatment of HIV-infected patients.

Protease Inhibitor Combination Therapy, Severity of Illness, and Quality of Life Among Children With Perinatally Acquired HIV-1 Infection

This study examines quality of life (QOL) among school-aged children with perinatally acquired HIV infection and compares QOL outcomes between treatment groups that differ according to the use of protease inhibitor (PI) combination therapy (PI therapy). To gain insights into how PI therapy might influence QOL, associations between severity of illness and QOL were also investigated. Cross-sectional data for 940 children, 5 to 18 years of age, who were enrolled in Pediatric AIDS Clinical Trials Group Late Outcomes Protocol 219 were used to examine domains of caregiver-reported QOL, as assessed with the General Health Assessment for Children, during 1999. The General Health Assessment for Children is an age-specific, modular, QOL assessment that was developed for the study with previously validated measures. QOL differences between treatment groups were estimated with linear and logistic regressions that controlled for sociodemographic characteristics (age, gender, race/ethnicity, maternal/caregiver education, and respondent) and severity-of-illness indicators related to receipt of PI therapy (AIDS status, log(10) CD4+ cell counts, and height-for-age z scores). The mean age of participants was 9.7 years. Most children were non-Hispanic black (54%) or Hispanic (31%), and 49% of the participants were female. At the 1999 study visit, approximately 14% of children had severe immune suppression (<15% CD4+ cells), whereas 62% of children had > or =25% CD4+ cells, ie, no immune suppression. Participants did exhibit some lag in growth, with mean height and weight z scores of -0.70 and -0.20, respectively. Twenty-eight percent of the children were reported to have met criteria for AIDS at study entry (1993-1999). When treatment groups were compared, children receiving PI therapy (72%) were older, had lower CD4+ cell percentages, and had lower height and weight z scores than did those receiving non-PI therapies. They were also more likely to have met criteria for AIDS at study entry. The most commonly used PIs were ritonavir (46%) and nelfinavir (63%). Health perceptions ratings for most children were at the upper end of the scale, whereas ratings for 25% of the children ranged over the lower 70% of scale scores. Almost one half of the children had at least some limitations in physical functioning, with more frequent limitations in energy-demanding activities (46%) than in basic activities of daily living (32%). The Behavior Problems Index was used to assess psychologic functioning. The mean total Behavior Problems Index score (9.34) and the proportion of children with extreme scores (23%) were consistent with values reported for chronically ill children and those at social and economic risk. One or more limitations in social/school functioning were reported for 58% of children. More than one third of the children (38%) experienced > or =1 physical symptoms that were at least moderately distressing. Health perceptions, physical functioning, psychologic functioning, social/school functioning, and overall HIV symptom scores did not differ between treatment groups. However, receipt of PI therapy was associated with an increased rate of diarrhea (28 vs 13%; adjusted odds ratio: 2.59; 95% confidence interval: 1.74-3.85). Severity of illness was associated with QOL in all domains except psychologic functioning. Higher log(10) CD4+ cell counts, higher height-for-age z scores, and absence of AIDS at study entry were independently associated with fewer social/school limitations and better HIV symptom scores. Health perceptions and physical functioning scores were associated with log(10) CD4+ cell counts and height z scores, respectively. QOL among children receiving PI therapy differed little from that among children receiving non-PI therapy, despite clinical indications of more advanced disease. Importantly, the study found no evidence of direct negative effects of PI therapy on QOL outcomes, other than an increased rate of diarrhea. Findings suggest that the effects of PI combination therapies to slow or to prevent disease progression and to increase CD4+ cell counts and height growth have the potential to improve QOL among children with HIV infection. However, many children do experience a constellation of functional impairments indicated by behavioral problems and clinical symptoms, with limitations in activities and in school performance. Comprehensive health services will continue to be required to minimize long-term illness and disability and to maximize children's potential as they move into adolescence and adulthood.