Methyl xanthine ( Theophylline, Aminophylline, Caffeine, Theobromine) drugs for asthma part 7
Mechanism of action:
- cyclic AMP turns into AMP degradation by phosphodiesterase, whereby the production of AMP leads to contraction in blood vessels and increases the release of adenosine and acetylcholine leading to bronchospasm and may lead to fatal arrhythmia.
- Therefore, this family of drugs works to stop the enzyme that was breaking down phosphodiesterase and converting cyclic AMP into AMP, and relaxation occurs as a result of cyclic AMP .
Pharmacological action:
When using methylxanthines, it affects:
- The brain: increases attention, fatigue,Sudden nervousness .
- On the lung: the most important effect is bronchodilation .
- On the heart: Increase the pressure on the heart, increase the number of beats, increase the preload and after load .
- On the stomach: It increases stomach acid and should be used with caution in ulcer patients .
- On the muscles: Increases muscle tremors due to over-contraction .
- On the kidneys: it affects slightly by increasing urine output .
Uses:
- It is considered a very strong drug and can be replaced by the B2 agonist and cortisone, but because of its many interactions with other drugs and because of the rapid appearance of its side effects (narrow therapeutic window), its use has been limited.
Side effects:
- Irregular heartbeat and an increase in the number of heartbeats are among the most important side effects .
Contraindication:
- Enzymes must be measured periodically, tests done and monitored, and extreme caution should be taken of its interactions with drugs, especially in chronic use.
- The dose must be adjusted to maintain the therapeutic window .