Half life metoprolol
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Understanding the Half-Life of Metoprolol
Introduction to Metoprolol Half-Life
Metoprolol is a selective β1-adrenoceptor antagonist commonly used to treat hypertension, angina, and arrhythmias. The half-life of a drug is a critical pharmacokinetic parameter that influences its dosing schedule and therapeutic efficacy. This article synthesizes research findings on the half-life of metoprolol, highlighting its pharmacokinetics in various populations and conditions.
General Half-Life of Metoprolol
The elimination half-life of metoprolol in healthy individuals typically ranges from 3 to 4.3 hours. Studies have shown that after a single dose, the half-life is approximately 4.3 ± 0.7 hours for an 80 mg dose and 3.8 ± 0.3 hours for a 50 mg dose2. This consistency is observed both in single-dose studies and during steady-state conditions2.
Impact of Liver Function on Metoprolol Half-Life
Liver function significantly affects the pharmacokinetics of metoprolol. In patients with hepatic cirrhosis, the elimination half-life is prolonged to about 7.2 ± 1.2 hours compared to 4.2 ± 1.1 hours in healthy controls3. This extension is due to impaired hepatic metabolism, which is the primary route of metoprolol elimination3.
Metoprolol in Dialysis Patients
In dialysis patients, the elimination half-life of metoprolol remains similar to that in healthy individuals, as its clearance is predominantly hepatic rather than renal. However, the half-life of its less active metabolite, α-hydroxymetoprolol, is prolonged, and the concentration of total radioactivity (sum of all metabolites) does not decline significantly during the dialysis interval4.
Genetic Factors Influencing Metoprolol Half-Life
Genetic variations can also impact the metabolism of metoprolol. Individuals who are poor hydroxylators of debrisoquine exhibit a significantly longer half-life and higher plasma concentrations of metoprolol. This genetic defect in drug oxidation leads to prolonged beta-adrenoceptor blockade and increased drug availability8.
Metoprolol in Geriatric Patients
In geriatric patients, the half-life of metoprolol averages about 3.5 hours, similar to younger populations. However, there is considerable variability in peak plasma concentrations, which may be attributed to differences in body weight, absorption, and first-pass metabolism9.
Sustained Release Formulations
Sustained release formulations of metoprolol succinate are designed to extend the drug's half-life and maintain therapeutic levels over a longer period. These formulations typically exhibit a half-life of 4-6 hours, allowing for once-daily dosing and improved patient compliance10.
Conclusion
The half-life of metoprolol varies depending on several factors, including liver function, genetic makeup, and patient age. Understanding these variations is crucial for optimizing dosing regimens and ensuring effective therapeutic outcomes. The standard half-life in healthy individuals is around 3-4.3 hours, but this can be significantly extended in patients with hepatic impairment or genetic differences in drug metabolism. Sustained release formulations offer a practical solution for maintaining consistent drug levels and enhancing patient adherence.
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Most relevant research papers on this topic
A comparison of a short half-life marker (low-dose isoniazid), a long half-life pharmacological indicator (low-dose phenobarbitone) and measurements of a controlled release 'therapeutic drug' (metoprolol, Metoros) in reflecting incomplete compliance by volunteers.
Phobarbitone measurements are more effective than isoniazid or metoprolol measurements in reflecting partial compliance over the previous 1 to 4 weeks.
Observational StudyPlasma levels and effects of metoprolol on blood pressure and heart rate in hypertensive patients after an acute dose and between two doses during long‐term treatment
Metoprolol effectively reduces systolic blood pressure and heart rate in patients with mild hypertension, with both doses showing a linear relationship to plasma concentrations.
Non-RCT
Highly CitedPharmacokinetics of Metoprolol in Patients with Hepatic Cirrhosis
Impaired liver function does not significantly affect the pharmacokinetics of metoprolol, with total body clearance and half-life related to galactose clearance and serum bilirubin.
Non-RCTThe Pharmacokinetics of Metoprolol and its Metabolites in Dialysis Patients
Metoprolol's pharmacokinetics in dialysis patients is similar to healthy volunteers, with hepatic metabolism playing a role in its elimination, and its elimination depends on dialysis technique.
Observational StudyBioavailability and disposition of metoprolol and hydrochlorothiazide combined in one tablet and of separate doses of hydrochlorothiazide.
Metoprolol and hydrochlorothiazide combined in a tablet do not significantly influence each other's bioavailability or time-course, making repeated doses unlikely to cause significant clinical interactions.
Non-RCTSulphasalazine induced selective IgA deficiency in rheumatoid arthritis.
Combining metoprolol and atenolol with ranitidine prolongs the elimination half life and increases the peak plasma metoprolol concentration by 33%, but does not significantly affect beta-blockade inhibition.
Non-RCTPharmacokinetic studies on the selectiveβ1-receptor antagonist metoprolol in man
Metoprolol is rapidly absorbed and excreted in the urine within 72 hours after oral administration, with a 3-hour elimination half-life for the parent compound and metabolites.
Non-RCTHighly CitedDefective metabolism of metoprolol in poor hydroxylators of debrisoquine.
Patients with a genetic defect in drug oxidation may have high plasma concentrations and prolonged effects when treated with metoprolol.
Non-RCTHighly CitedPlasma levels and effect on heart rate and blood pressure of metoprolol after acute oral administration in 12 geriatric patients.
Metoprolol's plasma levels in geriatric patients vary significantly, potentially due to body weight, absorption, and first-pass effects.
Non-RCT