Drugs used in acute asthma

Drugs used in acute asthma

Salbutamol
(B-agonist)
SE:
Tachycardia, arrhythmias, tremor, K+ up.

Hydrocortisone
(steroid)

Aminophylline
(Inhibits phosphodiesterase; [cAMP]).
SE:
pulse up; arrhythmias, nausea, seizures. The amount of IVI aminophylline may need altering according to the individual patient: always check the BNF. Monitor ECG.

Factors which may necessitate reduction of dose: Cardiac or liver failure, drugs which increase the half-life of aminophylline, eg cimetidine, ciprofloxacin, erythromycin, contraceptive steroids.

Factors which may require increase dose: Smoking, drugs which shorten the half-life, eg phenytoin, carbamazepine, barbiturates, rifampicin.

Aim for plasma concentration of 10-20µg/mL (55-110µmol/L). Serious toxicity (BP up, arrhythmias, cardiac arrest) can occur at concentrations ≥25µg/mL. Measure plasma K+: theophyllines may cause K+ up. Don't load patients already on oral preparations. Stick with one brand (bioavailability varies).