4-Hydroxyamphetamine

Hydroxyamphetamine is used in eye drops to dilate the pupil (a process called mydriasis) so that the back of the eye can be examined. This is a diagnostic test for Horner's syndrome. Patients with Horner's syndrome exhibit anisocoria brought about by lesions on the nerves that connect to the nasociliary branch of the ophthalmic nerve. Application of hydroxyamphetamine to the eye can indicate whether the lesion is preganglionic or postganglionic based on the pupil's response. If the pupil dilates, the lesion is preganglionic. If the pupil does not dilate, the lesion is postganglionic. It also has the tendency to falsely localize lesions. False localization can arise in cases of acute onset; in cases where a postganglionic lesion is present, but the nerve still responds to residual norepinephrine; or in cases in which unrelated nerve damage masks the presence of a preganglionic lesion. while Paremyd consists of a combination of 1% hydroxyamphetamine hydrobromide and 0.25% tropicamide. ==Pharmacology==

Pharmacodynamics Hydroxyamphetamine acts as an indirect sympathomimetic and induces the release of norepinephrine which leads to mydriasis (pupil dilation). The drug produces the head-twitch response, a behavioral proxy of psychedelic effects, when it is given by intracerebroventricular injection in animals. It additionally decreases metabolism of serotonin and certain other monoamines by inhibiting the activity of monoamine oxidases (MAOs), particularly type A (MAO-A). The inhibition of MAO-A prevents metabolism of serotonin and catecholamines in the presynaptic terminal, and thus increases the amount of neurotransmitters available for release into the synaptic cleft. Pharmacokinetics Hydroxyamphetamine is a major metabolite of amphetamine and a minor metabolite of methamphetamine. In humans, amphetamine is metabolized to hydroxyamphetamine by CYP2D6, which is a member of the cytochrome P450 superfamily and is found in the liver. 4-Hydroxyamphetamine is then metabolized by dopamine β-hydroxylase into 4-hydroxynorephedrine or eliminated in the urine. ==Chemistry==

Hydroxyamphetamine, also known as 4-hydroxy-α-methylphenethylamine, 4-hydroxyamphetamine, or α-methyltyramine, is a substituted phenethylamine and amphetamine derivative. It is the 4-hydroxylated analogue of amphetamine, the N-demethylated analogue of pholedrine (4-hydroxy-N-methylamphetamine), and the α-methylated analogue of tyramine (4-hydroxyphenethylamine). Other analogues include α-methyldopamine, corbadrine (levonordefrin; α-methylnorepinephrine), and dioxifedrine (α-methylepinephrine). It has a predicted log P of 0.58 to 1.4. Hydroxyamphetamine is used pharmaceutically as the hydrobromide salt. ==History==

Hydroxyamphetamine was first synthesized by 1910. Around 1997, Akorn, Inc., obtained the rights to both Paredrine and Paremyd, and in 2002, the company reintroduced Paremyd to the market as a fast acting ophthalmic mydriatic agent. In 2004, hydroxyamphetamine appeared to remain marketed only in the Czech Republic. ==Society and culture==

Names Hydroxyamphetamine is the generic name of the drug and its and , while hydroxyamfetamine is its . In the case of the hydrobromide salt, its generic name is hydroxyamphetamine hydrobromide and this is its . It is also known by synonyms including methyltyramine, norpholedrine, and oxamphetamine. The drug is sold under brand names including Paredrine, Paredrinex, Paremyd, Pedrolon, and Mycadrine. ==Other drugs==

4-Hydroxyamphetamine is also a metabolite of amphetamine and certain other amphetamines. ==Notes==