From the Guidelines
The half-life of 5mg Buspar (buspirone) is not explicitly stated in the provided evidence, but based on the information given, it can be inferred that the medication has a relatively short half-life, given its recommended dosing schedule of 5mg twice daily, with a maximum of 20mg three times daily 1. This dosing schedule suggests that the medication needs to be taken multiple times a day to maintain its therapeutic effects, which is consistent with a short half-life. However, it's essential to note that the exact half-life of 5mg Buspar is not provided in the evidence, and therefore, it's crucial to consult the medication's prescribing information or other reliable sources for accurate information. The provided evidence does mention that Buspar may take 2 to 4 weeks to become effective 1, which could be related to its pharmacokinetics and half-life, but this information is not directly relevant to the half-life of a specific dose. In clinical practice, the half-life of a medication is an important consideration for dosing and efficacy, and healthcare providers should consult reliable sources to determine the exact half-life of Buspar and adjust the dosing schedule accordingly. Some key points to consider when prescribing Buspar include its relatively short half-life, which may require multiple daily doses, and its potential interactions with other medications or substances that affect the CYP3A4 enzyme system 1. Overall, while the exact half-life of 5mg Buspar is not provided in the evidence, its relatively short half-life and recommended dosing schedule suggest that it should be taken multiple times a day to maintain its therapeutic effects.
From the FDA Drug Label
The average elimination half-life of unchanged buspirone after single doses of 10 mg to 40 mg is about 2 to 3 hours The half-life of 5 milligrams (mg) of Buspar (Buspirone) is not directly stated, but based on the information provided for doses of 10 mg to 40 mg, it can be inferred that the half-life is likely around 2 to 3 hours 2.
From the Research
Half-Life of Buspar (Buspirone)
- The half-life of Buspar (Buspirone) is reported to be around 2-3 hours in several studies 3, 4, 5.
- One study found the mean elimination half-life of Buspirone to be 2.1 hours 3.
- Another study reported the elimination half-life of Buspirone to be around 2.5 hours 4, 5.
- However, the half-life of Buspirone can be affected by various factors such as renal or hepatic impairment, with the half-life being twice as long in patients with hepatic impairment compared to healthy individuals 4.
- The half-life of an extended-release formulation of Buspirone was found to be around 9 hours, which is significantly longer than the immediate-release formulation 6.
Factors Affecting Half-Life
- Food intake can affect the absorption of Buspirone, with administration with food increasing the peak plasma concentration and area under the plasma concentration-time curve (AUC) of Buspirone 4, 5.
- Renal or hepatic impairment can significantly affect the half-life of Buspirone, with the half-life being longer in patients with impairment compared to healthy individuals 4.
- Other medications, such as verapamil, diltiazem, erythromycin, and itraconazole, can substantially increase the plasma concentration of Buspirone, while rifampicin can decrease the plasma concentrations of Buspirone 4.
Metabolism and Elimination
- Buspirone is extensively metabolized, with less than 1% of an administered dose excreted as unchanged drug 5.
- The main metabolite of Buspirone is 1-pyrimidinylpiperazine (1-PP), which may contribute to the pharmacological activity of Buspirone 3, 4, 6.
- The elimination half-life of 1-PP is around 6.1 hours, which is longer than the half-life of Buspirone 3.