Talk:Propranolol
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||Modafinil ||Purpose ||Common names||Inderal ||Substitutive name||Propranolol ||Systemic name||1-(isopropylamino)-3-(1-naphthyloxy)-2-propanol ||Psychoactive class||Beta blocker ||Chemical class||Arylpropanolamine ||Bioavailability||25% (oral) ||Routes of administration||Oral, Intravenous ||Dosage (oral) ||Light||10-40 mg ||Common||40-80 mg ||Strong||80-160 mg ||Heavy||160+ mg ||Duration (oral) ||Onset||30-60 minutes ||Peak||1-2 hours ||Offset||4-6 hours ||Afterglow||None ||Addiction potential||Very low ||Toxicity||Low to moderate ||Categories||Depressants, Beta blockers, Pharmaceuticals
Summary
Propranolol is a non-selective beta blocker used primarily to treat hypertension, anxiety, migraine prevention, and essential tremor. It works by blocking beta-adrenergic receptors, reducing the effects of adrenaline and noradrenaline on the heart and blood vessels.
History and culture
Propranolol was discovered in the 1960s by James W. Black, who was awarded the Nobel Prize in Physiology or Medicine in 1988 for his work on propranolol and cimetidine. It was the first clinically successful beta blocker and revolutionized the treatment of cardiovascular conditions.
Propranolol is on the World Health Organization's List of Essential Medicines and is widely used for performance anxiety, situational anxiety, and various cardiovascular conditions.
Chemistry
Propranolol is a synthetic compound belonging to the arylpropanolamine family. Chemically, it is 1-(isopropylamino)-3-(1-naphthyloxy)-2-propanol. It is a racemic mixture of two enantiomers: (S)-propranolol and (R)-propranolol. The (S)-enantiomer is approximately 100 times more active as a beta blocker than the (R)-enantiomer.
Pharmacology
Propranolol is a non-selective beta-adrenergic receptor antagonist, meaning it competitively blocks both beta-1 and beta-2 adrenergic receptors.
- Beta-1 receptors are primarily located in the heart; blocking them reduces heart rate, force of cardiac contraction, and blood pressure. - Beta-2 receptors are found in smooth muscle (bronchi, blood vessels); blocking them can cause bronchoconstriction.
Propranolol crosses the blood-brain barrier, making it useful for situational anxiety and performance anxiety by reducing peripheral symptoms of anxiety (tremor, tachycardia, sweating).
It also inhibits renin release from the kidneys, further contributing to its antihypertensive effects.
Subjective effects
Propranolol is not psychoactive in the traditional sense. It does not produce euphoria, hallucinations, or altered states of consciousness. Its effects are primarily physiological:
- Reduced heart rate and blood pressure - Reduced tremor - Reduced physical symptoms of anxiety - Possible fatigue or drowsiness - Possible cold extremities due to reduced peripheral circulation
Toxicity and harm potential
Propranolol has a low toxicity when used as prescribed. However, it carries important risks:
- **Bronchospasm**: Can be dangerous in patients with asthma or COPD due to beta-2 blockade - **Bradycardia**: Excessively slow heart rate - **Hypotension**: Low blood pressure - **Rebound hypertension/tachycardia**: Abrupt discontinuation can cause dangerous rebound effects, especially in patients with coronary artery disease - **Masking hypoglycemia symptoms**: Can mask tremors and tachycardia associated with low blood sugar in diabetics
It should not be abruptly discontinued in patients with coronary artery disease due to risk of rebound effects.
Legal status
Propranolol is a prescription medication in most countries. It is not a controlled substance. It is widely available through legitimate medical channels and is on the WHO List of Essential Medicines.
See also
External links
Literature
- Black JW. (1962). A new beta-adrenoceptor antagonist. Lancet.
- Black JW. (1964). The pharmacology of propranolol. British Medical Journal.
- Black JW, Crowther WJ, Shanks RG, et al. (1964). The mode of action of propranolol in thyrotoxicosis and anxiety states.