An effectiveness community-based clinical trial of Respirgard II and Fisoneb nebulizers for Pneumocystis carinii prophylaxis with aerosol pentamidine in HIV-infected individuals. Toronto Aerosol Pentamidine Study (TAPS) Group

Nebulized ivermectin for COVID-19 and other respiratory diseases, a proof of concept, dose-ranging study in rats

Ivermectin is a widely used antiparasitic drug with known efficacy against several single-strain RNA viruses. Recent data shows significant reduction of SARS-CoV-2 replication in vitro by ivermectin concentrations not achievable with safe doses orally. Inhaled therapy has been used with success for other antiparasitics. An ethanol-based ivermectin formulation was administered once to 14 rats using a nebulizer capable of delivering particles with alveolar deposition. Rats were randomly assigned into three target dosing groups, lower dose (80-90 mg/kg), higher dose (110-140 mg/kg) or ethanol vehicle only. A toxicology profile including behavioral and weight monitoring, full blood count, biochemistry, necropsy and histological examination of the lungs was conducted. The pharmacokinetic profile of ivermectin in plasma and lungs was determined in all animals. There were no relevant changes in behavior or body weight. There was a delayed elevation in muscle enzymes compatible with rhabdomyolysis, that was also seen in the control group and has been attributed to the ethanol dose which was up to 11 g/kg in some animals. There were no histological anomalies in the lungs of any rat. Male animals received a higher ivermectin dose adjusted by adipose weight and reached higher plasma concentrations than females in the same dosing group (mean Cmax 86.2 ng/ml vs. 26.2 ng/ml in the lower dose group and 152 ng/ml vs. 51.8 ng/ml in the higher dose group). All subjects had detectable ivermectin concentrations in the lungs at seven days post intervention, up to 524.3 ng/g for high-dose male and 27.3 ng/g for low-dose females. nebulized ivermectin can reach pharmacodynamic concentrations in the lung tissue of rats, additional experiments are required to assess the safety of this formulation in larger animals.

The pulmonary effects of long-term exposure to aerosol pentamidine: a 5-year surveillance study in HIV-infected patients

STUDY OBJECTIVES

To assess the effects of long-term exposure to aerosolized pentamidine (AP) for the prophylaxis of Pneumocystis carinii pneumonia on the pulmonary function.

DESIGN

The results of pulmonary function tests (PFTs) over a period of 5 years were retrospectively analyzed in a cohort of HIV-infected individuals.

SETTING

A government-funded AP clinic in a large metropolitan center in Canada.

PATIENTS

Among the cohort of 1,850 HIV-positive patients who received regular AP prophylaxis between 1989 and 2001 at the AP clinic, 83 received AP for >or= 5 years. Of these 83 patients, baseline and long-term follow-up PFT data were available for 79. These subjects formed the study population for this analysis.

RESULTS

The cohort was divided according to smoking status (smokers, 48%). The rate of decline of FEV(1) in the smokers over the 5-year period was statistically significant but was comparable to that expected of healthy smokers. As for the nonsmokers, there was no significant reduction in FEV(1). Flow rates at low lung volumes (ie, forced expiratory flow at 50% and 75% of FEV(1)) and low FEV(1)/FVC ratios showed significant declines in both smokers and nonsmokers. On the other hand, no significant changes in FVC, total lung capacity, residual volume, or diffusing capacity of the lung for carbon monoxide were observed. The apparent slight reduction in flow rates seems to be at the level of the small airways.

CONCLUSIONS

The PFT data suggest that AP can be well-tolerated over a 5-year period in HIV-infected patients with only modest reduction in flow rates at the level of the small airways, especially in smokers.

Regulation of bacterial drug export systems

The active transport of toxic compounds by membrane-bound efflux proteins is becoming an increasingly frequent mechanism by which cells exhibit resistance to therapeutic drugs. This review examines the regulation of bacterial drug efflux systems, which occurs primarily at the level of transcription. Investigations into these regulatory networks have yielded a substantial volume of information that has either not been forthcoming from or complements that obtained by analysis of the transport proteins themselves. Several local regulatory proteins, including the activator BmrR from Bacillus subtilis and the repressors QacR from Staphylococcus aureus and TetR and EmrR from Escherichia coli, have been shown to mediate increases in the expression of drug efflux genes by directly sensing the presence of the toxic substrates exported by their cognate pump. This ability to bind transporter substrates has permitted detailed structural information to be gathered on protein-antimicrobial agent-ligand interactions. In addition, bacterial multidrug efflux determinants are frequently controlled at a global level and may belong to stress response regulons such as E. coli mar, expression of which is controlled by the MarA and MarR proteins. However, many regulatory systems are ill-adapted for detecting the presence of toxic pump substrates and instead are likely to respond to alternative signals related to unidentified physiological roles of the transporter. Hence, in a number of important pathogens, regulatory mutations that result in drug transporter overexpression and concomitant elevated antimicrobial resistance are often observed.

Risk Factors for Prophylaxis Failure in Patients Receiving Aerosol Pentamidine for Pneumocystis carinii Pneumonia Prophylaxis

OBJECTIVE

The purposes of this study were (1) to determine the incidence of prophylaxis failure in HIV-infected patients receiving aerosol pentamidine (AP) for Pneumocystis carinii pneumonia (PCP) prophylaxis, and (2) to identify risk factors for PCP prophylaxis failure.

SETTING AND DESIGN

In Ontario, Canada, AP has been made available for outpatient PCP prophylaxis through a centralized government program, the Ontario Drug Distribution and Monitoring Program. Data from this administrative observational database were extracted for 2,227 patients who received AP between May 1989 and December 1998.

OUTCOME MEASUREMENTS

The incidence of breakthrough PCP (BPCP) was calculated from the database. A Cox regression model with time-varying covariates was created to examine factors associated with BPCP. The follow-up time was divided into three eras: 1989 to 1991, 1992 to 1994, and 1995 to 1998. These eras were meant to reflect major changes in antiretroviral medication regimens.

RESULTS

The overall risk of BPCP was 16.2% over a mean follow-up of 1.67 years. The overall BPCP rate was 9.7/100 patient-years, with rates of 8.8/100, 13.1/100, and 6.3/100 patient-years in each of the three treatment eras. In the multivariate analysis, significant risk factors for prophylaxis failure were low CD4 count, previous diagnosis of PCP, history of AIDS-defining conditions other than PCP, and antiretroviral treatment era defined above.

CONCLUSION

The overall rate of PCP prophylaxis failure has decreased significantly after 1995, coincident with the era of highly active antiretroviral therapies. Initiation of PCP prophylaxis remains necessary in patients with risk factors.

Effects of long-term aerosol pentamidine for Pneumocystis carinii prophylaxis on pulmonary function

OBJECTIVE

The purpose of the study was to evaluate the long-term effects of aerosolized pentamidine (AP) on the pulmonary function of HIV-positive individuals receiving AP for Pneumocystis carinii pneumonia (PCP) prophylaxis.

DESIGN

A retrospective analysis of serial pulmonary function tests (PFTs) performed on a cohort of HIV-positive patients who had received AP for >2 years.

METHODS

Of the 1,787 HIV-positive patients receiving AP prophylaxis in our database, 380 patients had been receiving AP for at least 24 months. Of these 380 patients, the PFTs at baseline and at 24 months after starting AP therapy were documented in 179. We compared the baseline PFTs of these 179 patients with results obtained 24 months later to evaluate if there was any change in pulmonary function parameters.

RESULTS

Baseline and 24-month PFT parameters (total lung capacity [TLC], FVC, residual volume [RV], FEV1, FEV1/FVC, maximum midexpiratory flow rate at 50% of vital capacity [MEF50], diffusion of carbon monoxide [DLCO]) were all within the normal ranges. However, AP therapy over 24 months was associated with a modest decline in lung volume parameters (TLC, FVC, RV), a slight reduction in flow rates (FEV1, FEV1/FVC, and MEF50), but no change in DLCO. The mean treatment duration was 23.8 months (range, 21 to 27 months).

CONCLUSIONS

Long-term AP therapy is associated with a mild combined restrictive and obstructive pulmonary defect. Since 24-month PFT parameters remained within the normal ranges, this level of decline is of unclear clinical significance. Overall, AP has good pulmonary tolerance when used up to 24 months for PCP prophylaxis in patients with normal baseline pulmonary function.