Pseudoephedrine pharmacokinetics

The rate at which any of the enantiomers is eliminated depends upon the urinary pH. At high pHs, excretion time is prolonged. At low pH ranges, excretion is accelerated. In controlled laboratory studies, where volunteer subjects were given either bicarbonate or ammonium chloride, the higher the urine pH, the more slowly the ephedrine and pseudoephedrine were excreted. Conversely, when the urine pH is low, excretion is accelerated (71). The importance of these observations is hard to assess, because without the addition of bicarbonate, urine pH values in the general population rarely approach 8.0. A study of pseudoephedrine pharmacokinetics in 33 volunteers who were not treated with drugs to alter urine pH found that these parameters could not be... 

It is excreted in breast milk at concentration constantly higher than those in maternal plasma. The elimination of pseudoephedrine is reduced in renal impairment. Hepatic dysfunction is unlikely to affect the pharmacokinetics of the drug. 

Sun, J., Wang, G., Wang, W., Zhao, S., Gu, Y., Zhang, J., Huang, M., Shao, F., Li, H., Zhang, Q., and Xie, H. (2005). Simultaneous determination of loratadine and pseudoephedrine sulfate in human plasma by liquid chromatography-electrospray mass spectrometry for pharmacokinetic studies. J. Pharm. Biomed. Anal. 39 217-224. 

Dickerson J, Perrier D, Mayersohn M, Bressler R. Dose tolerance and pharmacokinetic studies of L(+) pseudoephedrine capsules in man. Eur J Clin Pharmacol 1978 14 239-259. 

Example Pseudoephedrine hydrochloride (Actifed, Sudafed), phenylpropanolamine (Allerest, Dimetapp), phenylephrine HCK (Neo-Synephrine, Sinex), and pseudoephedrine (Actifed, Sudafed) frequently combined with an antihistamine, analgesic, or antitussive (anticough) in oral cold remedies Route Tablet, capsule, liquid Pregnancy category C Pharmacokinetic Absorbed by the GI tract, metabolized in liver and excreted in urine. Not removed by hemodialysis... 

All ephedra plants contain phenylalanine-derived alkaloids. These include (-)-ephedrine, (+)-pseudoephedrine, (-)-norephedrine, (+)-norpseudo-ephedrine (also called cathine because it is a major alkaloid of Catha edulis or khat, a plant used as a stimulant in North Africa), (-)-A-methylephedrine and (+)-A-methylpseudoephedrine, (+)-pseudoephedrine, and (+/-)-norephedrine (phenylpropanolamine). Significant enantioselective differences with regard to both pharmacokinetic and pharmacodynamic effects of these agents are possible. All of these alkaloids have important effects on the cardiovascular and respiratory systems, but not to the same degree. 

Hendershot PE, Antal EJ, Welshman IR, Batts DH, Hopkins NK Linezolid pharmacokinetic and pharmacodynamic evaluation of coadministratic i with pseudoephedrine HCI, phenylpropanolamine HCI, and dextremethorphan UBt J Clin Pharmacol (2001) 41,563-72. 

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