McKenna's Pharmacology for Nursing, 2e

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P A R T 1 0  Drugs acting on the respiratory system

those that do occur on occasion include headache, dry mucosa, myalgia, abdominal pain and nausea. Careful management (avoidance of dry or smoky environments, analgesics, use of proper inhalation technique, use of a humidifier and pushing fluids as appropriate) can help to make drug-related discomfort tolerable. Prototype summary: Sodium cromoglycate Indications: Prophylaxis of severe bronchial asthma; prevention of exercise-induced asthma. Actions: Inhibits the allergen-triggered release of histamine, SRSA and leukotrienes from mast cells; decreases the overall allergic response in the airways. Pharmacokinetics: Route Onset Peak Duration Inhaled Slow 15 mins 6–8 hours T 1/2 : 80 minutes; metabolised in the liver and excreted via exhalation. Adverse effects: Headache, dizziness, nausea, sore throat, dysuria, coughing, wheezing, nasal congestion. ■ ■ Assess for possible contraindications or cautions : allergy to prevent hypersensitivity reactions ; impaired renal or hepatic function, which could interfere with the metabolism or excretion of the drug, leading to a need for dose adjustment ; and pregnancy or breastfeeding, which require very cautious administration. ■ ■ Perform a physical examination to establish baseline data for assessing the effectiveness of the drug and the occurrence of any adverse effects associated with drug therapy. ■ ■ Assess the skin colour and lesions to monitor for adverse effects of the drug. ■ ■ Monitor respirations and adventitious sounds to evaluate drug effectiveness. ■ ■ Assess the patency of nares to determine the efficacy of inhaled preparations. ■ ■ Evaluate orientation to monitor adverse effects and headache. ■ ■ Evaluate liver and renal function tests to assess for potential problems with drug metabolism or excretion. Care considerations for people receiving a mast cell stabiliser Assessment: History and examination

M ast cell stabilisers A mast cell stabiliser prevents the release of inflamma- tory and bronchoconstricting substances when the mast cells are stimulated to release these substances because of irritation or the presence of an antigen. The currently available mast cell stabilisers are sodium cromoglycate ( Intal ) and nedocromil sodium ( Tilade ). Therapeutic actions and indications These drugs are used for the treatment of asthma and allergies (see Table 55.3 for usual indications). They work at the cellular level to inhibit the release of histamine (released from mast cells in response to inflammation or irritation) and inhibit the release of inflammatory mediators (see Figure 55.3). By blocking these chemical mediators of the immune reaction, they prevent the allergic asthmatic response when the respiratory tract is exposed to the offending allergen. Sodium cromoglycate is also used as an ophthalmic solution for the treatment of eye-related allergic symptoms, as a nasal spray for seasonal allergic rhinitis and in an inhaled form for the treatment of allergies. Pharmacokinetics Sodium cromoglycate is inhaled from a capsule and may not reach its peak effect for 1 week. It is also available as a nasal spray and as an ophthalmic solution, both of which have little systemic absorption. Nedocromil sodium is administered via metered dose inhaler. They are primarily active in the lungs, and most of the inhaled dose is excreted during exhalation or, if swallowed, excreted in urine and faeces. Contraindications and cautions Sodium cromoglycate and nedocromil sodium are con- traindicated in the presence of known allergy to the drug to prevent hypersensitivity reactions. They cannot be used during an acute attack, and people need to be instructed in this precaution. Because safety for use in pregnancy and breastfeeding has not been established , use should be reserved for those situations when the benefit to the mother greatly outweighs any potential risk to the fetus or neonate. Adverse effects Few adverse effects have been reported with the use of sodium cromoglycate and nedocromil sodium; measures to take to increase the effectiveness of the drug). ■ ■ Monitor the effectiveness of other measures to ease breathing.