Rate of Delivery

The concentrations of the drug at the desired sites and at the sites of toxicity within the respiratory tract will depend on the balance of the drug supply and clearance rates at these sites [37]. We may speculate that this is one of the reasons for the higher doses required for the delivery of topical medications by nebulizers (typically over 10-25 min) vs. metered-dose inhalers or dry powder inhalers that deliver the medication in one or two breaths. There is little doubt that prolonged inhalation reduces the patient's enthusiasm for the therapy. It is therefore appropriate to evaluate nebulizers in terms of their useful output, that is, the dose of the therapeutic or diagnostic agent delivered in the desired aerodynamic size range per unit time [145].

For systemic administration of readily absorbed molecules, the rate of delivery may be the rate-limiting step. This is evidenced with small molecules, such as morphine, whose absorption rate following deep lung delivery is practically indistinguishable from that after intravenous injection [146].

Coping with Asthma

Coping with Asthma

If you suffer with asthma, you will no doubt be familiar with the uncomfortable sensations as your bronchial tubes begin to narrow and your muscles around them start to tighten. A sticky mucus known as phlegm begins to produce and increase within your bronchial tubes and you begin to wheeze, cough and struggle to breathe.

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