Cardiovascular differences between phenylpropanolamine and its related norephedrine isomers in the rat.

Abstract

Various studies have confused the norephedrine and norpseudoephedrine isomers with phenylpropanolamine (PPA, d,l-norephedrine). This confusion has led us to investigate the pharmacological activity of the norephedrine (NOR) and norpseudoephedrine (NORP) isomers in the cardiovascular system of the urethane:chloralose anesthetized rat. Following intravenous administration, in a cumulative-dose fashion, l-NOR and PPA were the most potent compounds at increasing arterial blood pressure, while d-NOR, d-NORP, and l-NORP were relatively inactive at the doses tested (0.31-10 mg/kg). Prior reserpinization did not significantly shift the cumulative dose-response curves for l-NOR and PPA. Repetitive injections of PPA and l-NOR (1 mg/kg, 4 doses at 5-min intervals) failed to produce tachyphylaxis to the pressor response. On the other hand, when d-NORP was administered in a similar fashion, tachyphylaxis to the second and subsequent doses was observed. These studies demonstrate that significant mechanistic differences exist between these norephedrine isomers.

• Authors: F A Moya-Huff, P J Kiritsy, T J Maher
• Journal: Journal of pharmaceutical sciences (J Pharm Sci) Vol. 76 Issue 2 Pg. 114-6 (Feb 1987) ISSN: 0022-3549 [Print] United States
• PMID: 3572747 (Publication Type: Journal Article, Research Support, Non-U.S. Gov't)

Chemical References

• norpseudoephedrine
• Phenylpropanolamine
• Reserpine

Topics

• Animals
• Blood Pressure (drug effects)
• Dose-Response Relationship, Drug
• Male
• Optical Rotation
• Phenylpropanolamine (pharmacology)
• Rats
• Rats, Inbred Strains
• Reserpine (pharmacology)
• Stereoisomerism