Inhalation toxicity of aerosolized pentamidine isethionate in rats and dogs

A Review of the Comparative Anatomy, Histology, Physiology and Pathology of the Nasal Cavity of Rats, Mice, Dogs and Non-human Primates. Relevance to Inhalation Toxicology and Human Health Risk Assessment

There are many significant differences in the structural and functional anatomy of the nasal cavity of man and laboratory animals. Some of the differences may be responsible for the species-specific nasal lesions that are often observed in response to inhaled toxicants. This paper reviews the comparative anatomy, physiology and pathology of the nasal cavity of the rat, mouse, dog, monkey and man, highlighting factors that may influence the distribution of nasal lesions. Gross anatomical variations such as turbinate structure, folds or grooves on nasal walls, or presence or absence of accessory structures, may influence nasal airflow and species-specific uptake and deposition of inhaled material. In addition, interspecies variations in the morphological and biochemical composition and distribution of the nasal epithelium may affect the local tissue susceptibility and play a role in the development of species-specific nasal lesions. It is concluded that, while the nasal cavity of the monkey might be more similar to that of man, each laboratory animal species provides a model that responds in a characteristic and species-specific manner. Therefore for human risk assessment, careful consideration must be given to the anatomical differences between a given animal model and man.

Sirolimus-induced pneumonitis complicated by pentamidine-induced phospholipidosis in a renal transplant recipient: a case report

The proliferation signal inhibitors (PSIs)-sirolimus, everolimus, and temsirolimus-have been associated with a noninfectious pneumonitis characterized by lymphocytic alveolitis and bronciolitis obliterans with organizing pneumonia (BOOP). This condition usually occurs within the first year. Herein we presented a case of a deceased donor renal transplant with interstitial pneumonitis developing 6 years after a switch from tacrolimus to sirolimus due to chronic graft dysfunction. After the addition of intravenous pentamidine due to the suspicion of Pneumocystis pneumonia, there was marked clinical deterioration requiring intubation. Open lung biopsy revealed sirolimus-induced pulmonary toxicity (BOOP) with the additional finding of a drug-induced phospholipidosis (DIPL) that we ascribe to pentamidine treatment. After cessation of both drugs and application of corticosteroid therapy, there was only partial improvement. Eight months later the residual interstitial fibrosis demands supplemental home oxygen. We review the literature on PSI-induced pneumonitis and discuss the pathophysiology of a potential interaction with pentamidine. We caution against its use in the setting of PSI-induced pneumonitis. It is currently unknown whether these concerns also apply to prescription of other more commonly used medications associated with DIPL, eg, amiodarone and aminoglycosides.

Upper respiratory tract lesions in inhalation toxicology

This paper describes some important differences in normal histology of the upper respiratory tract of laboratory animals. It also provides examples of lesions observed or reported in the upper respiratory tract of laboratory animals, predominantly rodents, exposed via inhalation. The anatomy and physiology of upper respiratory tract tissues play a major role in the response to an insult, given that different epithelial types vary in susceptibility to injury and toxicant exposure concentrations throughout the airway vary due to airflow dynamics. Although dogs and nonhuman primates are utilized for inhalation toxicology studies, less information is available regarding sites of upper respiratory injury and types of responses in these species. Awareness of interspecies differences in normal histology and zones of transition from squamous to respiratory to olfactory epithelium in different areas of the upper respiratory tract is critical to detection and description of lesions. Repeated inhalation of chemicals, drugs, or environmental contaminants induces a wide range of responses, depending on the physical properties of the toxicant and concentration and duration of exposure. Accurate and consistent fixation, trimming, and microtomy of tissue sections using anatomic landmarks are critical steps in providing the pathologist the tools needed to compare the morphology of upper respiratory tract tissues from exposed and control animals and detect and interpret subtle differences.

Aerosolized pentamidine prophylaxis against AIDS-related Pneumocystis carinii pneumonia and its short- and long-term effects on pulmonary function in the Japanese

We evaluated the incidence of prophylaxis failure with aerosolized pentamidine (AP) for Pneumocystis carinii pneumonia (PCP) in Japanese patients with human immunodeficiency virus (HIV) infection, and we examined the short- and long-term effects of AP on pulmonary function. The patients inhaled 300 mg of pentamidine by ultrasonic nebulizer, after the inhalation of procaterol (80 micrograms), every 4 weeks. PCP developed in 2 of 16 patients receiving primary prophylaxis with AP, and in 4 of 13 patients with secondary prophylaxis. The CD4(+) T-lymphocyte count was very low in the patients with prophylaxis failure. The chest radiographic presentations were atypical in 4 of the 6 patients with prophylaxis failure. There were no significant changes in the vital capacity (VC), VC/predictive VC (%VC), forced expiratory volume in 1 s (FEV(1.0)), FEV(1.0)/forced vital capacity (FEV(1.0)%), and maximum expiratory flow rate at 25% of vital capacity (MEF(25))/height comparing values before and after initial AP treatment. However, a reduction of oxygen saturation (SpO(2)) of over 3% was noted in 4 patients during the initial AP administration. In 9 patients receiving AP prophylaxis for more than 36 months, we compared the pulmonary function parameters between the baseline and final observations (mean, 52.7 months). There were no changes in VC, %VC, FEV(1.0,) FEV(1.0)%, and SpO(2), but there was a statistically significant decline in MEF(25)/height after long-term AP treatment. We concluded that the incidence of prophylaxis failure with AP for PCP in Japanese patients was similar to that in Western patients, and that long-term AP treatment affected MEF(25)/height in spite of the safe pulmonary effects in short-term AP inhalation.