Clonidine is a centrally acting α2 adrenergic agonist and imidazoline receptor agonist used to treat high blood pressure, attention deficit hyperactivity disorder, anxiety disorders, tic disorders, withdrawal (from either alcohol, opioids, or smoking), migraine, menopausal flushing, diarrhea, and certain pain conditions. Clonidine treats high blood pressure by stimulating α2 receptors in the brain, which decreases peripheral vascular resistance, lowering blood pressure. It has specificity towards the presynaptic α2 receptors in the vasomotor center in the brainstem. This binding decreases presynaptic calcium levels, thus inhibiting the release of norepinephrine (NE). It has also been proposed that the antihypertensive effect of clonidine is due to agonism on the I1 receptor (imidazoline receptor), which mediates the sympatho-inhibitory actions of imidazolines to lower blood pressure. Clonidines mechanism of action in the treatment of ADHD is to increase noradrenergic tone in the prefrontal cortex (PFC) directly by binding to postsynaptic α2A adrenergic receptors and indirectly by increasing norepinephrine input from the locus coeruleus. Clonidine indicated in the treatment of hypertension. Clonidine hydrochloride tablets may be employed alone or concomitantly with other antihypertensive agents. The US Food and Drug Administration (FDA) has approved clonidine for the treatment of attention deficit hyperactivity disorder (ADHD), under the trade name of Kapvay alone or with stimulants in 2010, for pediatric patients aged 6–17 years.

Phentolamine (trade name Regitine) is a reversible nonselective α-adrenergic antagonist used for the control of hypertensive emergencies, most notably due to pheochromocytoma. Phentolamine produces its therapeutic actions by competitively blocking alpha-adrenergic receptors (primarily excitatory responses of smooth muscle and exocrine glands), leading to a muscle relaxation and a widening of the blood vessels. This widening of the blood vessels results in a lowering of blood pressure. The action of phentolamine on the alpha-adrenergic receptors is relatively transient and the blocking effect is incomplete. The drug is more effective in antagonizing responses to circulating epinephrine and/or norepinephrine than in antagonizing responses to mediator released at the adrenergic nerve ending. Phentolamine also stimulates β-adrenergic receptors and produces a positive inotropic and chronotropic effect on the heart and increases cardiac output. Phentolamine is indicated for the prevention or control of hypertensive episodes that may occur in a patient with pheochromocytoma as a result of stress or manipulation during preoperative preparation and surgical excision. Phentolamine is indicated for the prevention or treatment of dermal necrosis and sloughing following intravenous administration or extravasation of norepinephrine. Phentolamine is also indicated for the diagnosis of pheochromocytoma by the Phentolamine blocking test. Acute and prolonged hypotensive episodes, tachycardia, and cardiac arrhythmias have been reported. In addition, weakness, dizziness, flushing, orthostatic hypotension, nasal stuffiness, nausea, vomiting, and diarrhea may occur.

Phentolamine (trade name Regitine) is a reversible nonselective α-adrenergic antagonist used for the control of hypertensive emergencies, most notably due to pheochromocytoma. Phentolamine produces its therapeutic actions by competitively blocking alpha-adrenergic receptors (primarily excitatory responses of smooth muscle and exocrine glands), leading to a muscle relaxation and a widening of the blood vessels. This widening of the blood vessels results in a lowering of blood pressure. The action of phentolamine on the alpha-adrenergic receptors is relatively transient and the blocking effect is incomplete. The drug is more effective in antagonizing responses to circulating epinephrine and/or norepinephrine than in antagonizing responses to mediator released at the adrenergic nerve ending. Phentolamine also stimulates β-adrenergic receptors and produces a positive inotropic and chronotropic effect on the heart and increases cardiac output. Phentolamine is indicated for the prevention or control of hypertensive episodes that may occur in a patient with pheochromocytoma as a result of stress or manipulation during preoperative preparation and surgical excision. Phentolamine is indicated for the prevention or treatment of dermal necrosis and sloughing following intravenous administration or extravasation of norepinephrine. Phentolamine is also indicated for the diagnosis of pheochromocytoma by the Phentolamine blocking test. Acute and prolonged hypotensive episodes, tachycardia, and cardiac arrhythmias have been reported. In addition, weakness, dizziness, flushing, orthostatic hypotension, nasal stuffiness, nausea, vomiting, and diarrhea may occur.

The isolation and naming of ergotamine by Stoll occurred in 1925 but the complete elucidation of structure was not achieved until 1951, with synthesis following some 10 years later. Current sources of ergotamine include the isolation from field ergot and fermentation broth, as well as synthesis via coupling of (+)-lysergic acid with the appropriate synthetic peptidic moiety. Ergotamine was introduced into world commerce in 1921, and is currently marketed as its water soluble tartrate salt. Ergotamine is a partial agonist at various tryptaminergic receptors (including the serotonin receptor [5-HT2]) and at various α-adrenergic receptors in blood vessels and various smooth muscles. It is likely that the major activity of ergotamine and related alkaloids is one of agonism at the 5-HT1B/1D receptors, just as with the “triptan” antimigraine compounds. FDA-labeled indications for ergotamine tartrate are in the abortion or prevention of vascular headaches, such as migraine, migraine variant, cluster headache, and histaminic cephalalgia.

DL-Methamphetamine (also known as +/- Methamphetamin) is a central nervous system stimulant and sympathomimetic with actions and uses similar to DEXTROAMPHETAMINE. The smokable form is a drug of abuse and is referred to as crank, crystal, crystal meth, ice, and speed. Methamphetamine is a mixture of two isomers. One isomer called Dextro, or D Methamphetamine, is active as a central nervous system stimulant and it is a DEA Schedule 2 controlled drug commonly called “Meth” or “Speed”. Desoxyn, a prescription drug also contains D Methamphetamine. The other isomer, Levo, or L Methamphetamine is not a DEA controlled drug. It is found in an over the counter medicine called “Vicks Inhaler” or as the prescription drug, Selegiline. (+)-methamphetamine is the more physiologically active isomer. In addition to some medications, L Methamphetamine can be produced in the illegal production of street Methamphetamine.

DL-Methamphetamine (also known as +/- Methamphetamin) is a central nervous system stimulant and sympathomimetic with actions and uses similar to DEXTROAMPHETAMINE. The smokable form is a drug of abuse and is referred to as crank, crystal, crystal meth, ice, and speed. Methamphetamine is a mixture of two isomers. One isomer called Dextro, or D Methamphetamine, is active as a central nervous system stimulant and it is a DEA Schedule 2 controlled drug commonly called “Meth” or “Speed”. Desoxyn, a prescription drug also contains D Methamphetamine. The other isomer, Levo, or L Methamphetamine is not a DEA controlled drug. It is found in an over the counter medicine called “Vicks Inhaler” or as the prescription drug, Selegiline. (+)-methamphetamine is the more physiologically active isomer. In addition to some medications, L Methamphetamine can be produced in the illegal production of street Methamphetamine.

DL-Methamphetamine (also known as +/- Methamphetamin) is a central nervous system stimulant and sympathomimetic with actions and uses similar to DEXTROAMPHETAMINE. The smokable form is a drug of abuse and is referred to as crank, crystal, crystal meth, ice, and speed. Methamphetamine is a mixture of two isomers. One isomer called Dextro, or D Methamphetamine, is active as a central nervous system stimulant and it is a DEA Schedule 2 controlled drug commonly called “Meth” or “Speed”. Desoxyn, a prescription drug also contains D Methamphetamine. The other isomer, Levo, or L Methamphetamine is not a DEA controlled drug. It is found in an over the counter medicine called “Vicks Inhaler” or as the prescription drug, Selegiline. (+)-methamphetamine is the more physiologically active isomer. In addition to some medications, L Methamphetamine can be produced in the illegal production of street Methamphetamine.

DL-Methamphetamine (also known as +/- Methamphetamin) is a central nervous system stimulant and sympathomimetic with actions and uses similar to DEXTROAMPHETAMINE. The smokable form is a drug of abuse and is referred to as crank, crystal, crystal meth, ice, and speed. Methamphetamine is a mixture of two isomers. One isomer called Dextro, or D Methamphetamine, is active as a central nervous system stimulant and it is a DEA Schedule 2 controlled drug commonly called “Meth” or “Speed”. Desoxyn, a prescription drug also contains D Methamphetamine. The other isomer, Levo, or L Methamphetamine is not a DEA controlled drug. It is found in an over the counter medicine called “Vicks Inhaler” or as the prescription drug, Selegiline. (+)-methamphetamine is the more physiologically active isomer. In addition to some medications, L Methamphetamine can be produced in the illegal production of street Methamphetamine.

DL-Methamphetamine (also known as +/- Methamphetamin) is a central nervous system stimulant and sympathomimetic with actions and uses similar to DEXTROAMPHETAMINE. The smokable form is a drug of abuse and is referred to as crank, crystal, crystal meth, ice, and speed. Methamphetamine is a mixture of two isomers. One isomer called Dextro, or D Methamphetamine, is active as a central nervous system stimulant and it is a DEA Schedule 2 controlled drug commonly called “Meth” or “Speed”. Desoxyn, a prescription drug also contains D Methamphetamine. The other isomer, Levo, or L Methamphetamine is not a DEA controlled drug. It is found in an over the counter medicine called “Vicks Inhaler” or as the prescription drug, Selegiline. (+)-methamphetamine is the more physiologically active isomer. In addition to some medications, L Methamphetamine can be produced in the illegal production of street Methamphetamine.

Ephedrine (l-form) is an alkaloid, which was initially purified from Ephedra plant. The extract form Ephedra has been used in China for medicinal purposes for several thousand years. Ephedrine acts as an agonist at alpha- and beta-adrenergic receptors and indirectly causes the release of norepinephrine from sympathetic neurons. The drug crosses the blood brain barrier and stimulates the central nervous system. Ephedrine products are now banned in many countries, as they are a major source for the production of the addictive compound methamphetamine. FDA has approved ephedrine only for the treatment of clinically important hypotension occurring in the setting of anesthesia.