Terbutaline pharmacokinetics

S-terbutaline and R-terbutaline, respectively. The differences in clearance of enantiomers were primarily due to stereoselectivity in renal clearance. However, the nonrenal clearances of enantiomers were similar, suggesting a lack of stereoselectivity in the formation of sulfate conjugates in the liver. Indeed, urinary recoveries of conjugates after IV administration were similar for both enantiomers. After oral doses, the plasma concentrations of the R-enantiomer were approximately twice those of S-terbutaline. Intestinal metabolism in favor of the S enantiomer was considered to be the primary cause of stereoselectivity in terbutaline pharmacokinetics and bioavailability after its oral administration [117]. 

DS Davies. Pharmacokinetics of terbutaline after oral administration. Eur J Resp Dis Suppl 65 111-117, 1984. 

H-terbutaline sulfate In vivo—guinea pigs Pharmacokinetics, effect of lipid composition [86]... 

G. Hochhaus, and H. Moellmann, Beta-agonists terbutaline, albuterol, and feno-terol. Handbook of Pharmacokinetic/Pharmacodynamic Correlations (H. Derendorf and G. Hochhaus). CRC, New York, 1995, p. 299. 

S. Newman, K. Steed, G. Hooper, A. Kallen, and L. Borgstrom, Comparison of gamma scintigraphy and a pharmacokinetic technique for assessing pulmonary deposition of terbutaline sulphate delivered by pressurized metered dose inhaler, Pharm. Res. 72 231 (1995). 

Hochhaus, G., and Mollmann, H. (1992), Pharmacokinetic/pharmacodynamic characteristics of the beta-2-agonists terbutaline, salbutamol and fenoterol,Int.I. Clin. Pharmacol. Ther. Toxicol., 30, 342-362. 

Yuan, Y.-S. Shen, M. Study on pharmacokinetics and bioavailability of terbutaline by high-performance liquid chromatography with electrochemical detection. J. Chin. Pharm. Sci. 1994, 3, 152-156. 

TSP LC-MS in combination with coupled-column chromatography was used to separate and determine drag enantiomers of terbutaline (225 Da) in human plasma [76]. The (-)terbutaline enantiomer is pharmacologically active. The method was developed for single-dose pharmacokinetic studies to determine the plasma... 

Nyberg, L. (1984) Pharmacokinetic parameters of terbutaline in healthy man. An overview. European Journal of Respiratory Diseases Supplement, 134, 149-160. 

The major pharmacokinetic parameters of albuterol and terbutaline are listed in Tables 1 and 2. Irrespective of the route of administration, the pharmacokinetics of racemic albuterol are stereoselective with a faster disappearance of the active R enantiomer from plasma (Tables 1 and 2). This is due to stereoselective metabolism and renal clearance of albuterol in favor of the R enantiomer. Both the total body and renal clearances of R-albuterol are approximately 2 to 3 times higher than those of the distomer, resulting in a >3-fold higher maximum plasma concentrations of... 

In contrast to albuterol, plasma concentrations of R-terbutaline are significantly higher than those of its inactive S enantiomer (Table 1). Borgstrom et al. [117] investigated the plasma pharmacokinetics of terbutaline enantiomers after single IV and oral doses of single enantiomers or the racemate. The IV doses were 0.125 mg of S or R enantiomer or 0.5 mg of the racemate, and oral doses were 5 mg of R- or S-terbutaline or the racemate. Mean steady-state volumes of distribution of enantiomers were similar (1.9L/kg), although mean clearance was 0.19 and 0.13L/h/kg for... 

Borgstrom, L. Liu, C.X. Walhagen, A. Pharmacokinetics of the enantiomers of terbutaline after repeated oral dosing with racemic terbutaline. Chirality 1989, 1, 174-177. 

Oral terbutaline decreased serum theophylline levels by about 10% in 6 asthmatics, but the control of asthma was improved. Another study in asthmatic children, found that terbutaline elixir 75 micrograms/kg three times daily reduced steady-state serum levels of theophylline by 22%, but the symptoms of cough and wheeze improved. Yet another study found no changes in the pharmacokinetics of aminophylline in asthmatic children given terbutaline. ... 

Physicians often overlook pharmacodynamic and pharmacokinetic properties of aerosolized drugs. Differences in Pj-selectivity and the presence of a partial antagonistic activity make that salbutamol and terbutaline, are thought to be less associated with disturbing side effects and asthma mortality than fenoterol (54). 

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