Asthma's archives - Part 3

The Inhalant Aerosol Drug Delivery subcommittee agreed to limit the scope of the standard to S-HCs that are used with pMDIs, rather than those with other types of delivery devices, because pMDIs comprise the majority of medical inhalers prescribed — ventolin inhalers. In defining S-HC performance, the focus was on changes brought about by the addition of the S-HC to the pMDI, rather than the function of the pMDI itself or its clinical effects. Data for the pMDI alone are, therefore, required only to provide benchmark values against which to judge the effectiveness of the add-on device. Aspects not considered in the standard were pMDIs with integral spacers, S-HCs used with dry powder inhalers and nebulizers, S-HCs intended for use by patients in the intensive […]

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At the same time, in vitro testing of devices using breathing simulators with realistic variable flow rate patterns demonstrated that holding chambers might not deliver medication when used by infants or small children due to the low inspiratory flow rates generated by these patients. Sampling the aerosol at a constant flow rate, as described in other published monographs of test methods, has been the accepted procedure until recently. Further in vitro testing revealed that the delivered aerosol from S-HCs may be significantly reduced if the patient delayed inhalation. buy asthma inhalers

Continue reading " A new voluntary standard for spacers and holding chambers used with pressurized metered-dose inhalers (3) "

The primary purpose of an S-HC is to aid patient coordination of pMDI actuation and inhalation of the resulting aerosol spray. An important outcome of the S-HC design is the prevention of the ballistic or high-velocity component of the aerosol plume that is emitted from the actuator mouthpiece from depositing into the oropharyngeal cavity. This reduces the amount of active pharmaceutical ingredient swallowed and reduces the possibility of oral candidiasis from inhaled corticosteroids. In contrast with simple spacer devices without a valve at the mouthpiece or facemask, an additional function of the holding chambers is the retention of the aerosol for a short time following actuation of the pMDI. This can provide children, the elderly and poorly coordinated patients the opportunity to receive most of […]

Continue reading " A new voluntary standard for spacers and holding chambers used with pressurized metered-dose inhalers (2) "

Spacers and (valved) holding chambers (S-HC) are widely prescribed add-on devices for use with pressurized metered-dose inhaler (pMDI) medications used in the treatment of respiratory conditions such as asthma and chronic obstructive pulmonary disease. A variety of devices has appeared for sale in Canada during the 20-year period since the start of the widespread use of S-HCs, reflecting the desire of manufacturers to improve product performance and to extend their use to all patient age groups. Selected S-HCs currently available in the Canadian marketplace are listed in Table 1. Although many published laboratory studies with S-HCs exist, there is a lack of information on their performance when obtained under rigorously standardized conditions, making comparisons difficult. Factors influencing medication delivery include patient category (eg, infant, child […]

Continue reading " A new voluntary standard for spacers and holding chambers used with pressurized metered-dose inhalers (1) "