ASTHMA An inflammatory condition in
which there is recurrent reversible airways obstruction in response to irritant stimuli that are too weak to affect non-asthmatic subjects. symptoms shortness of wheezing breath ( especially cough. in breathing out)
decrease formation of cytokines,
in particular the Th2 cytokines that recruit and activate eosinophils and are responsible for promoting the production of IgE and the expression of IgE receptors. Glucocorticoids also inhibit the generation of the vasodilators PGE2 and PGI2, by inhibiting induction of COX-2 By inducing annexin 1, they could inhibit production of leukotrienes and platelet- activating factor.
Corticosteroids inhibit the allergen-induced
influx of eosinophils into the lung. Glucocorticoids up-regulate β2 adrenoceptors, decrease microvascular permeability, and indirectly reduce mediator release from eosinophils by inhibiting the production of cytokines (e.g. IL-5 and granulocyte-macrophage colony- stimulating factor) that activate eosinophils.
Unwanted effectsSystemic : Thinning of
the skin, Tendency to bruise,Osteoporosis, Muscle Weakness, Infections,Hypertension, etc.inhaled :Oropharyngeal candidiasis (thrush)sore throat and croaky voice [ use of spacing devices, reduces theseproblems ]
DRUGS FOR COUGHCOUGH : a
protective reflex that removes foreign material and secretions from the bronchi and bronchioles. It can be triggered by inflammation in the respiratory tract, for example by undiagnosed asthma or chronic reflux with aspiration, or by neoplasia. In these cases, cough suppressant (antitussant) drugs are useful.
MECHANISM OF COUGH SUPPRESSION Antitussive
drugs act by an ill-defined effect in the brain stem, depressing the cough centre. All opioid narcotic analgesics have antitussive actions in doses below those required for pain relief. Those used as cough suppressants are members of the group with minimal analgesic actions and addictive properties. New opioid analogues that suppress cough by inhibiting release of excitatory neuropeptides through an action on μ receptors on sensory nerves in the bronchi are being assessed.
EXAMPLES Codeine (methylmorphine) is a
weak opioid with considerably less addiction liability than the main opioids, and is a mild cough suppressant. It decreases secretions in the bronchioles, which thickens sputum, and inhibits ciliary activity. Constipation is common. Dextromethorphan and pholcodine are believed to have fewer adverse effects.