Theophylline (Purine Dimethylxanthine · Bronchodilator · PDE Inhibitor · Informational)
| Compound | Theophylline (1,3-Dimethylxanthine) |
| Chemical class | Alkaloid — Purine (Dimethylxanthine; xanthine alkaloid) |
| CAS | 58-55-9 |
| Primary source | Camellia sinensis (tea leaves; trace), synthesised pharmaceutically |
| Key applications | Pharmaceutical bronchodilator; asthma, COPD; PDE inhibitor; adenosine antagonist; informational reference |
| Claim strength | High (as pharmaceutical bronchodilator); Informational only (supplement) |
| Typical form | Pharmaceutical sustained-release tablet (Theo-Dur, Uniphyl); IV aminophylline (theophylline ethylenediamine); not a dietary supplement |
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Name origin: From theos (Greek: god) + phyllon (Greek: leaf) — referring to its isolation from tea leaves (Camellia sinensis, the “divine leaf”). Theophylline was isolated from tea by Albrecht Kossel in 1888 and synthesised by Emil Fischer and Lorenz Ach in 1895. It is the 1,3-dimethylxanthine isomer — closely related to caffeine (1,3,7-trimethylxanthine) and theobromine (3,7-dimethylxanthine). Despite being a natural product, theophylline is produced pharmaceutically (not extracted from tea) because tea concentrations (~0.8–2.8 mg/100 mL brewed tea) are far below therapeutic doses (10–20 μg/mL plasma — requiring 200–600 mg/day oral). Pharmacology — dual mechanism: (1) Non-selective PDE inhibitor — increasing cAMP in bronchial smooth muscle and inflammatory cells, producing bronchodilation and anti-inflammatory effects; (2) Adenosine receptor antagonist — blocking A1, A2A, A2B receptors, additional bronchodilatory and anti-inflammatory effects. Clinical use: Theophylline was a primary bronchodilator for asthma from the 1930s–1980s. Its narrow therapeutic index (toxic/therapeutic plasma ratio ~2:1) and multiple drug interactions caused high toxicity rates. It has been largely replaced by safer inhaled bronchodilators (salbutamol, tiotropium) and inhaled corticosteroids but retains use for: COPD exacerbations, nocturnal asthma, and in low-income settings where inhaled therapy is inaccessible. Supplement status: Pharmaceutical drug; not a supplement. Tea-derived theophylline at dietary doses has no pharmaceutical bronchodilator effect.
Theophylline — Pharmaceutical Context
Bronchodilator mechanism: Theophylline relaxes bronchial smooth muscle via cAMP elevation (PDE inhibition) and adenosine receptor antagonism. At therapeutic plasma levels (10–20 µg/mL), it produces clinically meaningful bronchodilation and reduces inflammatory cell activation (mast cells, eosinophils, neutrophils). The anti-inflammatory activity at sub-bronchodilatory doses (5–10 µg/mL) is of interest for COPD management where inflammation is the primary pathological driver. Pharmaceutical evidence: High.
Narrow therapeutic index — toxicity profile: At plasma levels above 20 µg/mL: nausea, vomiting, cardiac arrhythmias (atrial fibrillation, supraventricular tachycardia), and seizures. Deaths from theophylline toxicity occurred frequently in the era of aminophylline IV infusions without rigorous monitoring. Multiple drug interactions (CYP1A2 inhibitors increase theophylline levels: ciprofloxacin, erythromycin, fluvoxamine; CYP1A2 inducers decrease levels: smoking). This narrow therapeutic index is the primary reason theophylline has been displaced by safer alternatives. Critical safety reference.
Neonatal apnoea — unique indication: Theophylline (as aminophylline) and caffeine are used for apnoea of prematurity — stimulating respiratory drive in premature infants via adenosine A1 receptor antagonism in the brainstem. Caffeine citrate (Cafcit) is now preferred over aminophylline for neonatal apnoea due to wider therapeutic index. This represents one of the few remaining non-adult theophylline applications. Pharmaceutical evidence: High.
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Frequently Asked Questions — Theophylline
How much theophylline is in tea and is it pharmacologically significant?
Brewed black tea contains approximately 0.8–2.8 mg theophylline per 100 mL. A typical cup (240 mL) provides ~2–7 mg theophylline. The therapeutic bronchodilator dose is 200–600 mg/day (targeting 10–20 µg/mL plasma levels). Tea provides approximately 1–3% of the minimum therapeutic daily dose per cup — not pharmacologically significant for bronchodilation. Tea theophylline contributes to the mild stimulant effect alongside caffeine, but this is not its major contributor (caffeine provides ~95% of tea’s xanthine content).
What replaced theophylline for asthma management?
Theophylline has been largely replaced by: (1) Inhaled short-acting β2 agonists (SABA: salbutamol/albuterol) for acute relief — faster onset, higher β2 selectivity, fewer systemic effects; (2) Inhaled corticosteroids (ICS: beclomethasone, fluticasone) for maintenance anti-inflammatory therapy; (3) Inhaled long-acting β2 agonists (LABA: salmeterol, formoterol) for sustained bronchodilation; (4) Biologics (mepolizumab, dupilumab) for severe eosinophilic asthma. Theophylline retains a role for COPD and nocturnal asthma where its unique mechanism complements ICS/LABA therapy.
Does smoking affect theophylline levels?
Yes — significantly. Cigarette smoking induces CYP1A2 (the primary theophylline-metabolising enzyme), reducing theophylline half-life from ~7–9 hours (non-smokers) to ~3–5 hours (smokers). Smokers require 50–100% higher theophylline doses than non-smokers to achieve equivalent plasma levels. When a patient quits smoking, CYP1A2 induction decreases over weeks, potentially causing theophylline toxicity at the dose that was previously appropriate for them. Theophylline dose reduction and plasma level monitoring when a patient stops smoking is standard care.
Is roflumilast (Daliresp) related to theophylline?
Both are PDE inhibitors but different in selectivity. Theophylline is a non-selective PDE inhibitor (inhibits PDE1, 2, 3, 4, 5). Roflumilast is a highly selective PDE4 inhibitor — PDE4 is the predominant PDE isoform in inflammatory cells (neutrophils, macrophages, eosinophils). This selectivity allows roflumilast to achieve anti-inflammatory effects in COPD at doses that avoid theophylline’s cardiac arrhythmia risk (PDE3 inhibition). Roflumilast represents the drug class that theophylline’s clinical experience helped inspire, with PDE4 selectivity as the key improvement.
Related compounds: Caffeine, Theobromine, Piperine, Vasicinone
Claim-strength scale – High = multiple human RCTs; Moderate = limited trials or strong preclinical convergence; Emerging = early-stage lab or animal data.
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