Ensure correct brand is used as there are different formulations with different bioavailabilities. Complex interactions. Always check with existing drugs.

About:

-Methylxanthine Bronchodilator.

Action:

▪Competitive nonselective phosphodiesterase inhibitor
▪Raises intracellular cAMP, activates PKA.
▪Inhibits TNF alpha and leukotriene synthesis
▪Adenosine antagonist.

Indications:

▪Acute Bronchospasm - Asthma and COPD.
▪Pulmonary oedema

Interactions :- check BNF as this list is not complete

▪Metabolised by liver p450 system.
▪Smokers, Chronic alcohol, Liver inducers reduce drugs levels. Need increased dose for same effects.
▪Liver failure, heart failure, elderly, fluvoxamine, cimetidine, macrolides (erythromycin/clarithromycin)/ketoconoazole, fluconazole increase drug levels.
▪Increased Seizures with Quinolones.

Cautions:

▪Cardiac disease as may increase arrhythmias.
▪Epilepsy, Hyperthyroidism.
▪Fever, Porphyria, Diabetes Mellitus.

Contraindications:

▪Allergy.
▪Acute porphyria.

Side effects:

▪Arrhythmias, Palpitations.
▪Seizures, Delirium/Confusion, Insomnia, Restlessness.
▪Nausea, vomiting

Dose:

▪Aminophylline Oral : 225-450 mg bd for non smokers
▪Aminophylline Oral : 350-700 mg bd for smokers
▪Aminophylline IV : load 5 mg/kg (250-500 mg) and then 0.5 mg/kg/hour IVI
▪Maintain plasma levels at 10-20 mg/l (55-110 micromole/l)

Reference:Drive
PJ Mehta's Practical Medicine Principles and Practice of Pharmaceutical Medicine Second Edition Edited by Lionel D. Edwards .