Half life of albuterol
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Half-Life of Albuterol: Pharmacokinetics and Variability
Introduction to Albuterol Pharmacokinetics
Albuterol, a beta-2 adrenergic agonist, is widely used as a bronchodilator for the relief of bronchospasm in conditions such as asthma. Understanding its pharmacokinetics, particularly the half-life, is crucial for optimizing its therapeutic use and minimizing side effects.
Oral Administration of Albuterol
When administered orally, albuterol exhibits a two-compartment open model with first-order absorption kinetics. In a study involving healthy male volunteers, the elimination phase half-life of albuterol was determined to be approximately 6.5 hours1. This finding is consistent with other reports indicating similar half-life values following single-dose administration.
Comparative Bioavailability and Formulation Differences
The half-life of albuterol can vary slightly depending on the formulation. In a comparative study of three different oral formulations (two tablet forms and a syrup), the elimination phase half-life ranged from 4.8 to 5.5 hours2. This slight variation underscores the influence of formulation on the pharmacokinetics of albuterol.
Inhalation and Pulmonary Absorption
Inhaled albuterol, administered via a metered-dose inhaler, shows a different pharmacokinetic profile. The mean half-life of elimination for inhaled albuterol was found to be around 4.4 hours3. This shorter half-life compared to oral administration may be attributed to the rapid absorption and distribution phases associated with pulmonary delivery.
Enantiomer-Specific Pharmacokinetics
Albuterol exists as a racemic mixture of R- and S-enantiomers, each exhibiting distinct pharmacokinetic properties. The half-life of the R-enantiomer (R-albuterol) averages around 4 hours, while the S-enantiomer (S-albuterol) has a slightly longer half-life of approximately 6 hours6. These differences are important for understanding the drug's overall pharmacodynamic effects and potential side effects.
Urinary Excretion and Metabolism
Following inhalation, a significant portion of albuterol is excreted unchanged in the urine, with a half-life of approximately 3.8 hours5. This rapid excretion highlights the efficiency of the renal clearance mechanism for albuterol and its metabolites.
Pediatric Considerations
In children with asthma, the pharmacokinetics of albuterol administered via multidose dry powder inhaler (MDPI) and hydrofluoroalkane (HFA) inhaler were found to be comparable. The terminal half-life of elimination in this population was consistent with the values observed in adults, further supporting the use of these inhalation devices in pediatric patients7.
Conclusion
The half-life of albuterol varies depending on the route of administration and the specific formulation used. Oral administration typically results in a half-life of around 6.5 hours, while inhaled forms exhibit a shorter half-life of approximately 4.4 hours. The pharmacokinetics of albuterol's enantiomers also differ, with the R-enantiomer having a shorter half-life compared to the S-enantiomer. These variations are crucial for tailoring albuterol therapy to individual patient needs and optimizing its clinical efficacy.
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Most relevant research papers on this topic
Multiple‐Dose Albuterol Kinetics
Multiple-dose albuterol administration reaches steady-state plasma levels by the third day, with a elimination phase half-life of 6.5 hours.
Non-RCTComparative bioavailability and pharmacokinetics of three formulations of albuterol.
The bioavailability of albuterol from tablet and solution formulations is equivalent, with rapid absorption and comparable maximum drug concentrations.
RCTPharmacokinetics of (R,S)-Albuterol after aerosol inhalation in healthy adult volunteers.
Inhaled (R,S)-albuterol reaches maximum plasma concentrations in 12.6 minutes, with female subjects experiencing faster peak concentrations and higher mean peak concentrations than male subjects.
Non-RCTAlbuterol: An Adrenergic Agent for Use in the Treatment of Asthma Pharmacology, Pharmacokinetics and Clinical Use
Albuterol is an effective and safe treatment for acute asthma, with aerosolized inhalation being the best option for first-line management.
Highly CitedAbsorption, excretion and urinary metabolic pattern of 3 H-albuterol aerosol in man.
Albuterol aerosol is readily absorbed and excreted mainly in the urine as the free drug and at least two metabolites.
Non-RCTPharmacokinetic and Pharmacodynamic Characteristics and Safety of Inhaled Albuterol Enantiomers in Healthy Volunteers
Inhaled albuterol enantiomers show similar pharmacokinetics and safety, with no evidence of in vivo racemization and no interconversion between the two enantiomers.
Non-RCTPharmacokinetics and pharmacodynamics of albuterol multidose dry powder inhaler and albuterol hydrofluoroalkane in children with asthma.
Albuterol MDPI and HFA have comparable pharmacokinetics and pharmacodynamics in children with asthma after a single 180-g dose.
RCTA placebo‐controlled, double‐blind trial of the long‐term effects of albuterol administration in patients with cystic fibrosis
Albuterol maintenance therapy significantly improves spirometry in cystic fibrosis patients compared to placebo.
RCTComparison of inhaled albuterol powder and aerosol in asthma.
200 micrograms of albuterol powder is as safe and effective as 180 micrograms of albuterol aerosol for treating asthma in chronic reversible obstructive airway disease patients.
RCTThe effect of inhaled albuterol in moderate to severe asthma.
Four times daily dosing of albuterol did not lead to deterioration of asthma control in patients with moderate to severe asthma.
RCT