BMA Concise Guide to Medicine & Drugs

Theophylline/Aminophylline

Brand names [theophylline] Slo-Phyllin, Uniphyllin; [aminophylline] Norphyllin, Phyllocontin

Used in the following combined preparations [theophylline] Do-Do Chesteze

QUICK REFERENCE

Drug group Bronchodilator

Overdose danger rating High

Dependence rating Low

Prescription needed No (except for injection)

Available as generic Yes

GENERAL INFORMATION

Theophylline (and aminophylline, which breaks down to theophylline in the body) is used to treat bronchospasm (constriction of the air passages). It improves breathing in patients suffering from asthma, bronchitis, and emphysema.

It is usually taken continuously for prevention, but aminophylline injections are sometimes used for acute attacks.

Slow-release formulations of the drugs produce beneficial effects lasting for up to 12 hours. These preparations may be prescribed twice daily, but they are also useful as a single dose taken at night to prevent night-time asthma and early morning wheezing.

Treatment with theophylline must be monitored because the effective dose is very close to the toxic dose. Some adverse effects, such as indigestion, nausea, headache, and agitation, can be controlled by regulating the dosage and checking blood levels of the drug.

INFORMATION FOR USERS

Follow instructions on the label. Call your doctor if symptoms worsen.

How taken/used Tablets, SR tablets, SR capsules, injection.

Frequency and timing of doses 3–4 x daily (tablets); every 12 or 24 hours (SR tablets/SR capsules). Take at the same time each day.

Dosage range Adults 375–1,000mg daily, depending on which product is used.

Onset of effect Within 30 minutes (by mouth); within 90 minutes (SR tablets/SR capsules).

Duration of action Up to 8 hours (by mouth); 12–24 hours (SR tablets/SR capsules).

Diet advice None.

Storage Keep in original container at room temperature out of the reach of children.

Missed dose Take as soon as you remember. If your next dose is due within 2 hours, take half the dose now (short-acting preparations) or forget about the missed dose and take your next dose now (SR preparations). Return to your normal dose schedule thereafter.

Stopping the drug Do not stop taking the drug without consulting your doctor; stopping the drug may lead to worsening of the underlying condition.

OVERDOSE ACTION

Seek immediate medical advice in all cases. Take emergency action if chest pains, confusion, or loss of consciousness occur.

POSSIBLE ADVERSE EFFECTS

Many adverse effects are related to blood levels of the drug and may be controlled by adjusting the dosage. The most common effects are on the gastrointestinal and central nervous systems. If you experience severe nausea, vomiting, diarrhoea, abdominal pain, or insomnia, discuss with your doctor. You should also consult your doctor if you get headaches or become unusually agitated. If palpitations occur, you should stop taking the drug and contact your doctor immediately.

INTERACTIONS

General note Many drugs interact with theophylline. Some antibiotics, antidepressants, and anti-epileptics increase the effect of theophylline by increasing its blood level. Taken with theophylline, high doses of beta 2 agonists such as salbutamol increase the risk of low blood potassium levels. Discuss with your doctor.

SPECIAL PRECAUTIONS

Be sure to tell your doctor if:

· You have a liver problem.

· You have angina or irregular heart beat.

· You have high blood pressure.

· You have epilepsy.

· You have hyperthyroidism.

· You have porphyria.

· You have peptic ulcers.

· You smoke.

· You are taking other medicines.

Pregnancy Safety in pregnancy not established. Discuss with your doctor.

Breast-feeding The drug passes into the breast milk and may affect the baby. Discuss with your doctor.

Infants and children Reduced dose necessary according to age and weight.

Over 60 Reduced dose may be necessary.

Driving and hazardous work No known problems.

Alcohol Avoid excess as this may alter levels of the drug and may increase gastrointestinal symptoms.

How to take your tablets Several factors such as drug interactions, certain medical conditions (e.g. heart or liver failure), and smoking can affect theophylline levels. All brands release the drug differently, resulting in varying levels. For this reason, it is important always to use the same brand.

PROLONGED USE

No problems expected.

Monitoring Periodic checks on blood levels of this drug are usually required.