title: The beta-adrenergic blockade withdrawal phenomenon.
abstract: Early trials of beta-blocking drugs in angina indicated an increase in symptoms above pretreatment levels when placebo was substituted for active drug. In addition there were reports of sudden death after beta-blockade withdrawal. There is evidence of increased beta-receptor sensitivity as demonstrated by increased responsiveness to isoprenaline after propranolol withdrawal. This may be due to increased beta-receptor population. Other factors may be a reversal of the reduced free triiodothyronine levels or of the favourable rightward shift of oxyhaemoglobin dissociation curve, or increased platelet aggregation when the beta-blocking drug is stopped. Also, progression of the disease process may have taken place during treatment which is unmasked on withdrawal. Studying different beta-blocking agents we have observed that in normal volunteers withdrawal of pindolol, which has partial agonist properties, was not associated with post blockade increase in response to isoprenaline. The beta-blocker withdrawal syndrome is a real phenomenon, although overall the incidence is probably not high. Exertion may be a prerequisite for the development of significant clinical sequelae, therefore exercise should be restricted on withdrawal of beta-blocking drugs. The dosage should be reduced gradually, particularly the final decrement.
mesh_terms: D000319:Adrenergic beta-Antagonists / Q000009:adverse effects*; D000818:Animals; D002395:Catecholamines / Q000378:metabolism; D006801:Humans; D010974:Platelet Aggregation; D011433:Propranolol / Q000009:adverse effects; D011943:Receptors, Adrenergic, beta / Q000502:physiology; D012083:Renin / Q000378:metabolism; D013375:Substance Withdrawal Syndrome / Q000378:metabolism / Q000503:physiopathology*; D013564:Sympathetic Nervous System / Q000502:physiology; D013963:Thyroid Hormones / Q000378:metabolism; D013997:Time Factors
chemical_list: D000319:Adrenergic beta-Antagonists; D002395:Catecholamines; D011943:Receptors, Adrenergic, beta; D013963:Thyroid Hormones; D011433:Propranolol; D012083:Renin