Labetalol is a blocker of both alpha- and beta-adrenergic receptors that is used as an antihypertensive. It may be used alone or in combination with other antihypertensive agents, especially thiazide and loop diuretics. The capacity of labetalol HCl to block alpha receptors in man has been demonstrated by attenuation of the pressor effect of phenylephrine and by a significant reduction of the pressor response caused by immersing the hand in ice-cold water ("cold-pressor test"). Labetalol HCl's beta1-receptor blockade in man was demonstrated by a small decrease in the resting heart rate, attenuation of tachycardia produced by isoproterenol or exercise, and by attenuation of the reflex tachycardia to the hypotension produced by amyl nitrite. Beta2-receptor blockade was demonstrated by inhibition of the isoproterenol-induced fall in diastolic blood pressure. Both the alpha- and beta-blocking actions of orally administered labetalol HCl contribute to a decrease in blood pressure in hypertensive patients. Labetalol HCl consistently, in dose-related fashion, blunted increases in exercise-induced blood pressure and heart rate, and in their double product. The pulmonary circulation during exercise was not affected by labetalol HCl dosing. Single oral doses of labetalol HCl administered to patients with coronary artery disease had no significant effect on sinus rate, intraventricular conduction, or QRS duration. The atrioventricular (A-V) conduction time was modestly prolonged in two of seven patients. In another study, IV labetalol HCl slightly prolonged A-V nodal conduction time and atrial effective refractory period with only small changes in heart rate. The metabolism of labetalol is mainly through conjugation to glucuronide metabolites. These metabolites are present in plasma and are excreted in the urine and, via the bile, into the feces. Approximately 55% to 60% of a dose appears in the urine as conjugates or unchanged labetalol within the first 24 hours of dosing. Labetalol has been shown to cross the placental barrier in humans. Only negligible amounts of the drug crossed the blood-brain barrier in animal studies. Labetalol is approximately 50% protein bound. Neither hemodialysis nor peritoneal dialysis removes a significant amount of labetalol HCl from the general circulation.

Droxidopa (Northera, Chelsea Therapeutics) is a synthetic catecholamino acid precursor of norepinephrine indicated for the treatment of orthostatic dizziness or lightheadedness in adult patients with symptomatic neurogenic orthostatic hypotension (NOH) caused by primary autonomic failure, dopamine beta-hydroxylase deficiency, and non-diabetic autonomic neuropathy. Droxidopa was approved as oral therapy in February 2014 under the FDA’s accelerated approval program. Droxidopa is directly metabolized to norepinephrine by dopadecarboxylase. The specific mechanism of action of the drug is not known completely, but it is supposed to exert the pharmacological effects through norepinephrine and not through the parent molecule or other metabolites. It increases blood flow to the brain by stimulating peripheral arterial and venous vasoconstriction.

Racepinephrine or racemic epinephrine is a mixture of levo and dextro isomers of epinephrine act as a nonselective agonist at adrenergic receptors. It is a bronchodilator used in the temporary relief of mild symptoms of intermittent asthma including wheezing, shortness of breath. Inhaled racepinephrine became available in September 2012 as a nonprescription treatment for bronchospasm based on a 1986 US Food and Drug Administration rule. Besides, racemic epinephrine relieves respiratory distress in hospitalized infants with bronchiolitis and is safe but does not abbreviate hospital stay. Morbidity associated with bronchiolitis as identified by parents persists for at least one week after hospital discharge in most infants.

Epinephrine is a sympathomimetic catecholamine. It acts as a naturally occurring agonist at both alpha and beta-adrenergic receptors. Three pharmacologic types have been identified: alpha 1-, alpha 2-, and beta-adrenergic receptors. Each of these has three subtypes, characterized by both structural and functional differences. The alpha 2 and beta receptors are coupled negatively and positively, respectively, to adenylyl cyclase via Gi or Gs regulatory proteins, and the alpha 1 receptors modulate phospholipase C via the Go protein. Subtype expression is regulated at the level of the gene, the mRNA, and the protein through various transcriptional and postsynthetic mechanisms. Through its action on alpha-adrenergic receptors, epinephrine lessens the vasodilation and increased vascular permeability that occurs during anaphylaxis, which can lead to loss of intravascular fluid volume and hypotension. Through its action on beta-adrenergic receptors, epinephrine causes bronchial smooth muscle relaxation and helps alleviate bronchospasm, wheezing and dyspnea that may occur during anaphylaxis. Epinephrine also alleviates pruritus, urticaria, and angioedema and may relieve gastrointestinal and genitourinary symptoms associated with anaphylaxis because of its relaxer effects on the smooth muscle of the stomach, intestine, uterus and urinary bladder. Epinephrine increases glycogenolysis, reduces glucose up take by tissues, and inhibits insulin release in the pancreas, resulting in hyperglycemia and increased blood lactic acid.

Adenosine monophosphate (AMP) is a nucleotide, consisting of a phosphate group, the sugar ribose, and the nucleobase adenine. AMP is an activator of several enzymes in the tissues. In the glycolytic pathway, the enzyme phosphofructokinase is inhibited by ATP but the inhibition is reversed by AMP, the deciding factor for the reaction being the ratio between ATP and AMP. In medicine, AMP is used mainly as an alternative to adenosine for treatment of ischemia and as a tool compound to measure hyperresponsiveness of airways.

Mephentermine, an amphetamine-derived phenethylamine, is an alpha 1 adrenergic receptor agonist and a hypertensive drug. Mephentermine is mainly used as a vasopressor agent with a sympathomimetic action, primarily causing release of noradrenaline and increasing cardiac output due to positive inotropic effect on the myocardium. The injectable preparation of mephentermine is commonly used for the short-term treatment of various hypotensive states such as shock or hypotension accompanying myocardial infarction or spinal anesthesia or surgical procedures like cesarean section. There is evidence on the fetal metabolic effect and placental transfer of mephentermine. However, a few studies have shown that mephentermine is as effective as phenylephrine in preventing maternal hypotension after spinal anesthesia and has similar effect on neonatal outcome. It is being widely used in developing countries like India as it is much more economical than phenylephrine and offers ease of use as it does not necessitate multiple dilutions as injectable. It is also available in India as 10 mg oral tablets. Despite it was thought earlier to have a little stimulant effect its abuse potential has increased, especially in sports due to its stimulant properties. Like amphetamines, it has shown to increase athletic performance in strength exercises and endurance in a dose of 14 mg/70 kg body weight. It has been proposed that phentermine, which is the main metabolite of mephentermine, acts by inhibiting monoaminoxidases A and B. Mephentermine adverse effects has been related to CNS simulation, excessive rises in blood pressure, and arrhythmias. Wyamine Sulfate (brand name of mephentermine sulfate) approved by FDA in 1951 was discontinued in USA.

Hydroxyamphetamine is a derivative of amphetamines. Hydroxyamphetamine is intended mainly as local eye drops for diagnostic purposes. It is indirect sympathomimetic agent which cause dilation of the eye pupil before diagnostic test. Among the minor side effects from its use are: change in color vision, difficulty seeing at night, dry mouth, headache, increased sensitivity of eyes to sunlight, muscle stiffness or tightness and temporary stinging in the eyes. The main use of hydroxyamphetamines as eye drops is the diagnosis of Horner's syndrome which is characterized by nerve lesions. Hydroxyamphetamine hydrobromide is a component of FDA approved brand drug - Paremyd sterile ophthalmic solution (Hydroxyamphetamine hydrobromide, USP 1.0%, Tropicamide, USP 0.25%). Hydroxyamphetamine is an indirect-acting sympathomimetic, while tropicamide acts as a parasympatholytic.

Spiclomazine induces apoptosis associated with the suppression of migration and invasion in pancreatic carcinoma cells

Fosenazide (phosphabenzide, gidifen, hydiphen or hydrazide of diphenylphosphinylacetic acid) is a tranquilizer. It possesses the central N-cholinolytic, antiadrenergic and antiserotonin effects. Fosenazide is prescribed in Russia only for the treatment of alcohol withdrawal syndrome.

Fenproporex is a central and indirect-acting sympathomimetic. It was developed as an anorectic drug. Their anorectic effects are believed to be a result of adrenergic activation. Fenproporex has never been approved by the US Food and Drug Administration (FDA) for sale in the US due to lack of efficacy and safety data. There is a paucity of randomized, placebo-controlled trials on Fenproporex. These studies suggest that Fenproporex is modestly effective in promoting weight loss. Data from these studies are insufficient to determine the risk-benefit profile of Fenproporex. Abuse potential and amphetamine-like adverse effects are causes for concern. Adverse effect most frequently reported are: insomnia, anxiety, depression, irritability, dry mouth.