Inhalation generation, control

In rats, the administration of fullerene by inhalation, as nano- and microparticles generated by aerosol, does not lead to lesions and only a little increase of protein concentration in bronchoalveolar lavage fluid was obtained (Baker et al., 2007). Recently, Sayes et al. (2007) analyzed in vivo pulmonary toxicity of C60 and C60(OH)24, after intratracheal instillation in rats. They verified only transient inflammatory and cell injury effects, 1 day postexposure, without differences from water-instilled controls. No adverse lung tissue effects were measured, and the results demonstrated little or no differences in lung toxicity effects between the C60 and fiillerols, compared to controls. 

Moreover, the system will release the aerosol cloud only when the pre-programmed optimal inhalation flow is generated by the patient. These features enable a controlled and targeted delivery to the lung. 

Dry powder inhalers are generally described as breath actuated devices, because the inspiratory airstream releases the dose from the dose system and supplies the energy for the generation of fine drug particles from the powder formulation. Because the efficiency of dose release and powder disintegration increases with increasing inspiratory flow rate for most DPIs, these devices would be better described as breath controlled devices. In Section 3.9, the effect of resistance and clinical conditions on the flow curve and relevant flow parameters for DPIs are discussed. 

Groups of 100 male and 100 female Syrian golden hamsters, six weeks of age, were exposed to chloroprene (99.6% pure) by whole-body inhalation at concentrations of 0 (control), 10 or 50 ppm [0, 36 or 180 mg/m for 6 h per day on five days per week for 18 months. The chloroprene was generated in the same manner as that described for the rat study by the same investigators. Surviving animals were killed and all animals evaluated. Survival was 88% in control, 92% in 10-ppm and 93% in 50-ppm males and 63%, 75% and 72% for females. No increase in tumour incidence was observed in exposed animals (Trochimowicz et al., 1998). 

Inhalation. The respiratory system is an important portal of entry, and for evaluation purposes animals must be exposed to atmospheres containing potential toxicants. The generation and control of the physical characteristics of such contaminated atmospheres is technically complex and expensive in practice. The alternative—direct instillation into the lung through the trachea—presents problems of reproducibility as well as stress and for these reasons is generally unsatisfactory. 

White Phosphorus. No information on developmental toxicity in humans was located. In two one-generation reproduction studies, the incidence of developmental effects in rats orally exposed to white phosphorus was not significantly different from the incidence in vehicle-only controls (Bio/dynamics 1991 IRDC 1985). These studies administered relatively low doses of white phosphorus, and additional oral studies utilizing higher exposure levels could help determine the potential developmental toxicity of white phosphorus. Inhalation and dermal studies would provide information on developmental toxicity by these routes. 

Nebulizer jet nebulization ultrasonic nebulization. Generates small particles with higher delivery capacities than pMDIs and DPIs no coordination required. Inconvenient long inhalation times poor dose control lack of portability expensive. More compact and portable devices breath enhanced nebulizers dosimetric nebulizers. 

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