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Methylxanthine Bronchodilator

Theophylline (Oral Modified Release)

Brand names: Uniphyllin, Slo-Phyllin, Nuelin SA

Theophylline is an oral xanthine bronchodilator used as add-on therapy in asthma and COPD when other treatments are insufficient.

Dosing — being independently re-sourced

ClinCalc Pro is rebuilding its dose data from primary open sources — the manufacturer SmPC (eMC), the WHO Model Formulary and other official references — under clinician review. This drug's structured dose is not yet published here. Confirm all doses against the product SmPC and your local formulary before prescribing.

US labelling (FDA)

Reference — US labelling, may differ from UK

DOSAGE AND ADMINISTRATION Theophylline (Anhydrous) Extended-Release Tablets 400 or 600 mg can be taken once a day in the morning or evening. It is recommended that Theophylline (Anhydrous) Extended-Release Tablets be taken with meals. Patients should be advised that if they choose to take Theophylline (Anhydrous) Extended-Release Tablets with food it should be taken consistently with food and if they take it in a fasted condition it should routinely be taken fasted. It is important that the product whenever dosed be dosed consistently with or without food. Theophylline (Anhydrous) Extended-Release Tablets are not to be chewed or crushed because it may lead to a rapid release of theophylline …

Source: US FDA prescribing information (openFDA / DailyMed), label dated 2025-12-04. Accessed 2026-06-12. US dosing and indications can differ from UK practice — use UK sources for prescribing decisions.

Clinical monograph

How it works

It causes bronchodilation and has some anti-inflammatory effect (via phosphodiesterase inhibition and adenosine antagonism); the mechanism is not fully defined.

Prescribing in practice

  • It has a narrow therapeutic index — toxicity (nausea, palpitations, arrhythmia, seizures) can occur near therapeutic levels, so monitor plasma levels.
  • Many factors alter its level — smoking and enzyme inducers lower it; macrolides, ciprofloxacin, heart failure and liver disease raise it.
  • Modified-release brands differ and are not interchangeable — prescribe by brand.

Monitoring

Monitor plasma theophylline levels (and at dose or interacting-drug changes) and watch for toxicity.

Counselling the patient

  • Stay on the same brand.
  • Report palpitations, persistent vomiting, or feeling shaky or agitated.
  • Tell your clinician if you start or stop smoking, as it changes how the drug works.

Evidence & guidelines

An add-on bronchodilator in asthma/COPD (NICE NG80/NG115), used with level monitoring because of its narrow margin.

Reference: BTS/SIGN Asthma Guidelines 2019; GOLD COPD 2024; Drug verified in RxNorm (NLM); confirm dosing against the manufacturer SPC (eMC). Verify against your local formulary and current prescribing references before prescribing. Monograph status: clinician-reviewed (2026-07-04).

Related

Curated clinical cross-links plus same-class fallbacks.

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