Coadministration with food appears to enhance bioavailability. Despite complete absorption, propranolol has a  variable bioavailability due to extensive first-pass metabolism. Hepatic impairment therefore increases its bioavailability. The main metabolite 4-hydroxypropranolol, with a longer half-life (5.2–7.5 hours) than the parent compound (3–4 hours), is also pharmacologically active. Most of the metabolites are excreted in the urine.Propranolol is a highly lipophilic drug achieving high concentrations in the brain. The duration of action of a single oral dose is longer than the half-life and may be up to 12 hours, if the single dose is high enough (e.g., 80 mg). Effective plasma concentrations are between 10 and 100 mg/L. Toxic levels are associated with plasma concentrations above 2000 mg/L. History
Scottish scientist James W. Black developed propranolol in the 1960s. It was the first beta-blocker effectively used in the treatment of coronary artery disease and hypertension. In 1988, Black was awarded the Nobel Prize in Medicine for this discovery. Propranolol was inspired by the early β-adrenergic antagonists dichloroisoprenaline and pronethalol. The key difference, which was carried through to essentially all subsequent beta blockers, was the inclusion of an oxymethylene group (-O-CH2-) between the aryl and ethanolamine moieties of pronethalol, greatly increasing the potency of the compound. This also apparently eliminated the carcinogenicity found with pronethalol in animal models. Newer, more cardio-selective beta blockers (such as bisoprolol, nebivolol, carvedilol, or metoprolol) are now used preferentially in the treatment of hypertension.
Xanthoma disseminatum is a rare cutaneous condition that preferentially affects males in childhood, characterized by the insidious onset of small, yellow-red to brown papules and nodules that are discrete and disseminated. : 717 It is a histiocytosis syndrome. See also
Non-X histiocytosis
List of cutaneous conditions

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