Ephedrine mydriasis

Sneddon JM, Turner P. Ephedrine mydriasis in h3 pertensiQn and the response to treatment. CtinPhanmcol Ther( 9 ) 10, 64-71. 

These results indicate that in these new ester mydriatics, the structural factors, which influence the development of this type of pharmacological action are similar to those made evident by the chemical investigations of Jowett and Pyman and the pharmacological work of Marshall, Dale, Laidlaw and Cushny on the tropeines. The nature of the basic component is obviously important since mydriasis is produced by simple bases such as ephedrine. As regards the nature of the esterifying acid, Jowett and Pyman drew the following conclusions — ... 

Ephedrine stimulates CNS and produces restlessness, insorrmia, anxiety and tremors. Ephedrine produces mydriasis on local as well as systemic administration. 

The phenomena of systemic cocaine poisoning are largely those of sympathetic stimulation but not as consistently as with epinephrine. The sympathetic stimulation is mainly central (midbrain) but partly peripheral. The chief manifestations of sympathetic stimulation are (1) sensitization to epinephrine (but antagonization to ephedrine) by peripheral action, (2) mydriasis and slight exophthalmos by central and peripheral action, and (3) cardiac acceleration (chiefly central). Other sympathetic symptoms are constriction of the blood vessels, erection of hair, and relaxation of the intestines. High concentrations of cocaine paralyze all smooth muscles. Procaine also produces... 

Ephedrine occurs in white, rosette, or needle crystals, or as an unctuous mass. It is soluble in water, alcohol, chloroform, ether, and in liquid petrolatum, the latter solution being turbid if the ephedrine is not dry. Ephedrine melts between 34 and 40°C, depending upon the amount of water it contains it contains not more than 0.1% of ash its solutions are alkaline to litmus it readily forms salts with acids and it responds to the usual tests for alkaloids. Ephedrine excites the sympathetic nervous system, depressing smooth and cardiac muscle action, and produces effects similar to those of epinephrine. It produces a rather long-lasting rise of blood pressure and mydriasis and diminishes hyperemia. The alkaloid may be used in 0.5 to 2% oil spray. 

Ephedrine produces mydriasis when applied locally to the conjunctiva, as well as upon systemic absorption. In humans, there is a striking disparity between the mydriatic effects of ephedrine in Caucasians and in Chinese or blacks. It is most active in the first, less active in the second, and almost completely inactive in the last. The reason for this differential effect on irides of different color has not yet been completely explained. 

Many of the adrenergic agents produce a transient, incomplete mydriasis when applied to the eye. Cycloplegia does not occur. Ephedrine sulfate in a 3% concentration has been used for this purpose. As has been indicated, the effect is most positive in Caucasians with light-colored irides. Ephedrine is not considered to be a good mydriatic, as it is none too reliable and its solutions are quite irritating to the cornea. Phenylephrine should probably be the adrenergic mydriatic of choice. 

Sympathomimetic syndromes include tachycardia, hypertension, hyperthermia, sweating, mydriasis, hyperreflexia, agitation, delusions, paranoia, seizures and cardiac arrhythmias. These are commonly caused by amphetamine and its derivatives, cocaine, proprietary decongestants, e.g. ephedrine, and theophylline (in the latter case, excluding psychiatric effects). 

Most sympathomimetics produce mydriasis that is abolished by light reflexes. The mydriasis produced by ephedrine is not abolished by the application of light. Accommodation is also not affected by ephedrine, unlike with other sympathomimetics. 

Trendelenburg (150) has reviewed some of the history concerning the isolation and pharmacological behavior of ephedrine, which was isolated by Nagai in 1887 and studied byMiura (151). The last author stated that ephedrine produced a respiratory arrest, decreased pulse rate, induced a cardiac arrest in diastole, and a mydriasis in the frog. With dogs and cats a stimulation of the respiration and pulse, clonic convulsions, and hyperthermia are noted. Airila (152) and Morita (153) observed an intense motor stimulation provoked by ephedrine in the rabbit (20 mg.). 

Comprehensive reviews about the chemistry and pharmacology of ephedra and its use in sports and weight loss products have recently been published.The pharmacological effects of maHUANG are generally attributed to ephedrine, which include central nervous system (CNS) stimulation, peripheral vasoconstriction, elevation of blood pressure, bronchodilatation, cardiac stimulation, decrease of intestinal tone and motility, mydriasis, and tachycardia, among others (zhou). The central stimulant action of ephedrine appears to be mediated by /-adrenoceptors and not by dopamine receptors. ... 

Local instillation of thymoxamine 0.1% eye-drops completely reversed the mydriasis produced by 5%) ephedrine, but not that produced by 5% cphedrinc together with 0.5% homatropine (21 ). 

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