Central nervous system ephedrine derivatives

Many alkaloids have pronounced biological properties, and a substantial number of the pharmaceutical agents used today are derived from naturally occurring amines. As a few examples, morphine, an analgesic agent, is obtained from the opium poppy Papaver somnifemm. Cocaine, both an anesthetic and a central nervous system stimulant, is obtained front the coca bush Erythroxylon coca, endemic to upland rain forest areas of Colombia, Ecuador, Peru, Bolivia, and western Brazil. Reserpine, a tranquilizer and antihypertensive, comes from powdered roots of the semitropical plant Rauwolfia serpentina. Ephedrine, a bronchodilator and decongestant, is obtained front the Chinese plant Ephedra sinica. 

Ephedrine is the predominant alkaloid of ephedra plants. Other phenylalanine-derived alkaloids found in ephedra plants are (+)-pseudoephedrine, (—)-norephedrine, (-l-)-norpseudoephedrine, (l)-A-methylephedrine and phenylpropanolamines. Ephedrine is a potent central nervous system (CNS) stimulant. Because ephedra is both an a- and p-adrenergic agonist, ingestion of quantities over 50 mg lead to a rise in blood pressure, heart rate and cardiac output. 

Almost all analogs of ephedrine and epinephrine have been synthesized and subjected to pharmacological evaluation. Some of them are used in medicine. The list includes amphetamine or benzedrine (XX), deoxy-ephedrine (XXI), vonedrine (XXII), propadrine (XXIII), paredrine (XXIV), veritol (XXV), suprifen (XXVI), and neosynephrine (XXVII). They are advocated as vasoconstrictors in otolaryngology. The marketed form of neosynephrine is the Z-isomer. Amphetamine and deoxyephedrine are now better known for their stimulating action on the central nervous system (78, 79) and are used by persons whose duties call for long periods of alertness. The d-forms of both amines are more effective than the Z-forms in this respect. The commercial names of cZ-deoxyephedrine and cZ-amphetamine are pervitin and dexedrine, respectively. Two catechol derivatives have been recommended as substitutes for epinephrine. They are epinine (XXVIII) and corbasil (XXIX). 

Central nervous system (CNS) stimulants are drugs that produce generalized stimulation of the brain or spinal cord which may lead to eonvulsion. They are of limited therapeutic value beeause of their convulsant activities. There are, however, some that are used as respiratory stimulants (e.g., Nikethamide) and others like the xanthine derivatives have many pharmacological actions and uses. Sympathomimetic amines like amphetamines and ephedrine, which are potent CNS stimulants, are discussed elsewhere. 

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