From the FDA Drug Label
In a study of 12 elderly (62 to 79 years old) and 12 young (25 to 33 years old) healthy subjects, the clearance of S-enantiomer of propranolol was decreased in the elderly. Additionally, the half-life of both the R- and S-propranolol were prolonged in the elderly compared with the young (11 hours vs. 5 hours)
The half-life of short-acting propranolol is approximately 5 hours in young healthy subjects, and 11 hours in elderly subjects 1.
- Key factors that influence the half-life of propranolol include:
- Age
- Renal function
- Hepatic function However, the half-life can vary depending on individual factors, such as age and renal or hepatic function.
From the Research
The half-life of short-acting propranolol is approximately 3-6 hours, as indicated by the most recent and highest quality study available 2. This means that after this time period, half of the active drug has been eliminated from the body. Due to this relatively short half-life, short-acting propranolol is typically dosed multiple times per day, usually 2-4 times daily, to maintain therapeutic blood levels. The medication is metabolized primarily in the liver through first-pass metabolism, which significantly reduces its bioavailability to about 25-35% of the ingested dose, as noted in 2. This pharmacokinetic property explains why propranolol doses may need adjustment in patients with liver disease. Some key points to consider when prescribing short-acting propranolol include:
- The short half-life distinguishes it from long-acting propranolol formulations (Inderal LA, Innopran XL), which are designed for once-daily dosing.
- Understanding propranolol's half-life is important for anticipating the duration of its beta-blocking effects, which include reduction in heart rate, blood pressure, and cardiac output through competitive inhibition of beta-adrenergic receptors, as discussed in 3.
- The half-life of short-acting propranolol can vary among individuals, ranging from 1.5 to 3 hours, as reported in 2.
- The drug's effects are related to its plasma concentrations, and individual differences in response are largely due to variations in plasma binding, as noted in 2. It is essential to consider these factors when determining the optimal dosing regimen for patients taking short-acting propranolol, and to prioritize the single most recent and highest quality study available, which in this case is 2.