Theophylline Mechanism of Action (MOA), Clinical Uses, Side Effects, Toxicity, Therapeutic Range

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Theophylline

What is Theophylline?

Theophylline, also known as 1,3-dimethylxanthine, is a member of the xanthine family – methylxanthine group drug. It is commonly used in treatment of respiratory diseases such as chronic obstructive pulmonary disease (COPD) and asthma.
Theophylline is structurally and pharmacologically similar to theobromine and caffeine, and it is a commonly present in tea (Camellia sinensis) and cocoa (Theobroma cacao).

theophylline level toxicity side effects 3

Mechanism of action (MOA)

Theophylline has two different actions in the airways.

  1. Causes bronchodilation by relaxing the smooth muscles of the bronchial airways and pulmonary blood vessels.
  2. Causes non-bronchodilator prophylactic effects by reducing airway responsiveness to substances like histamine, methacholine, adenosine and allergens.

Bronchodilation is caused by the increase in of cyclic AMP inside smooth muscle cells . Cyclic AMP is degraded by type III and type IV phosphodiesterase (PDE).
Theophylline competitively inhibits two isozymes, type III and type IV phosphodiesterase (PDE), that causes increase in cyclic AMP, possibly resulting in bronchodilation.

Theophylline also binds to the adenosine A2B receptor and blocks adenosine mediated bronchoconstriction.
In inflammatory conditions, it causes activation of histone deacetylase in order to prevent transcription of inflammatory genes.

The main actions of theophylline involve:

  • Bronchodilation by Relaxing bronchial smooth muscle
  • Anti-inflammatory effects
  • Positive inotropic effects – Increases contractility and efficiency of heart muscle
  • Positive chronotropic effects – Increases heart rate (positive chronotropic)
  • Increases blood pressure
  • Increases renal blood flow
  • Stimulatory effect on central nervous system, mainly on the medullary respiratory center.

We’ve discussed the pharmacology of most common & essential drugs, & their Mechanism of actions, contraindications, cautions, side effects, use in pregnancy, use in breast feeding, adult dose, pediatric dose in our Pharmacology Made Easy eBook.

Medical uses

Theophylline is used in some common lung diseases such as:

  • Asthma
  • Chronic obstructive pulmonary disease (COPD)
  • Bronchitis
  • Emphysema
  • Infant apnea

Theophylline range in serum

Bronchodilation occurs within the serum concentration range of 5-20 mcg/mL. Most of the studies have shown, clinically important improvement in control of respiratory symptoms occurs in peak serum concentrations > 10 mcg/mL. However patients with mild disease may benefit from lower concentrations of theophylline. Theophylline has narrow therapeutic window, so at serum concentrations > 20 mcg/mL, both the frequency and severity of adverse reactions increase.  Theophylline overdose may cause seizures and potentially fatal arrhythmias.

So in most of the patients, maintaining peak serum concentrations between 10 and 15 mcg/mL will achieve most of the drug’s potential therapeutic benefit while minimizing the risk of serious adverse events.

Theophylline side effects

  • Anxiety
  • Arrhythmias
  • Diarrhoea
  • Dizziness
  • Gastrointestinal discomfort
  • Gastrooesophageal reflux disease
  • Headache
  • Hyperuricaemia
  • Nausea
  • Palpitations .
  • Seizure
  • Skin reaction
  • Sleep disorders
  • Tremor urinary disorders
  • Vomiting

Theophylline Toxicity/Overdose

Toxicity/overdose can cause severe and intractable vomiting, agitation, restlessness, dilated pupils, sinus tachycardia, and
hyperglycaemia.

More serious effects are haematemesis, convulsions, and life threatening supraventricular and ventricular arrhythmias. Severe hypokalaemia may develop rapidly.

Symptoms of acute overdose are:

  • Severe nausea and vomiting will occur with acute and chronic overdose, sustained-release preparations, immediate-release preparation that lasts for a long time.
  • Abdominal pain
  • Mild metabolic acidosis
  • Hypokalemia (↓K)
  • Hypophosphatemia
  • Hypomagnesemia (↓Mg)
  • Hypocalcemia and hypercalcemia (↓ and ↑ Ca)
  • Hyperglycemia
  • Tachycardia & arrythmia

Theophylline in Pregnancy

Neonatal irritability and apnoea have been reported when mothers use Theophylline during pregnancy. But it can be taken as normal during pregnancy as it is particularly important that asthma should be well controlled during pregnancy.

Theophylline in breast feeding

It is present in breast milk and causes irritability in infant when a pregnant mother takes Theophylline. But modified-release preparations are preferable to use. Theophylline can be taken as normal during breastfeeding.

Additional biochemical information

Chemical Names :

    • 1,3-dimethyl-7H-purine-2,6-dione
    • 1,3-dimethylxanthine
    • Teofilina
    • Theophyllin
    • Theophylline anhydrous

Product Ingredients : 

    • Theophylline sodium glycinate

Molecular Formula:

C7H8N2O2

     

IUPAC Name :

StartFragment1,3-dimethyl-2,3,6,7-tetrahydro-1H-purine-2,6-dione

Volume of distribution : 

    • 0.3 to 0.7 L/kg

Protein binding : 

    • 40% protein bound, primarily to albumin

Chemical structure of Theophylline : 

theophylline leven toxicity side effects
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