Xylometazoline, also spelled xylomethazoline, is a medication which is used to improve symptoms of nasal congestion, allergic rhinitis, and sinusitis. Xylometazoline was patented in 1956 and came into medical use in 1959. It is on the World Health Organization's List of Essential Medicines, the most effective and safe medicines needed in a health system. The drug works by stimulating adrenergic receptors on the lamina propria of blood vessels in the nose. The decongestant effect is due to constriction of large veins in the nose which swell up during the inflammation of any infection or allergy of the nose. The smaller arteries are also constricted and this causes the colour of the nasal epithelium to be visibly paler after dosage. The standard adult solution strength is 0.1% w/v xylometazoline (or 1 mg per 1 mL solution), and the dose for children under 12 is usually 0.05% (0.5 mg/mL).

Tetrahydrozoline is an alpha adrenergic receptor agonist, which is used in form of nasal solution or spray (Tyzin) for decongestion of nasal and nasopharyngeal mucosa.

Naphazoline is a direct acting sympathomimetic adrenergic alpha-agonist used to induce systemic vasoconstriction, thereby decreasing nasal congestion and inducing constriction around the conjunctiva. The sympathomimetic action of Naphazoline constricts the smaller arterioles of the nasal passages, producing a decongesting effect. Naphazoline ophthalmic causes constriction of blood vessels in the eyes. It also decreases itching and irritation of the eyes. aphazoline constricts the vascular system of the conjunctiva. It is presumed that this effect is due to direct stimulation action of the drug upon the alpha adrenergic receptors in the arterioles of the conjunctiva resulting in decreased conjunctival congestion. Naphazoline belongs to the imidazoline class of sympathomimetics. Naphazoline is a direct acting sympathomimetic drug, which acts on alpha-adrenergic receptors in the arterioles of the nasal mucosa. This activates the adrenal system to yield systemic vasoconstrction. In producing vasoconstriction, the result is a decrease in blood flow in the nasal passages and consequently decreased nasal congestion. The vasoconstriction means that there is less pressure in the capillaries and less water can filter out, thus less discharge is made. Naphazoline is primarily indicated in conditions like Corneal vascularity, Hyperaemia, Itching, Nasal congestion, and can also be given in adjunctive therapy as an alternative drug of choice in Sinusitis.

Glycine (Cly) is a natural amino acid neurotransmitter that acts as a co-agonist at Glutamate [NMDA] receptors in the brain and is an activator of glycine receptors, GLRA1-3, GLRB. The abnormal Gly levels have been implicated in neuropsychiatric disorders. Alterations in Gly levels are implicated in several diseases of the central nervous system. Glycine was studied in phase II of clinical trials in patients with schizophrenia. The results have shown that using of glycine was associated with reduced symptoms with promising effect sizes and a possibility of improvement in cognitive function. Besides, glycine was also studied in clinical trials phase II in children with cystic fibrosis. The clinical, spirometric and inflammatory status of subjects with cystic fibrosis improved after just 8 weeks of glycine intake, suggesting that this amino acid might constitute a novel therapeutic tool for these patients. In addition, Gly was proposed as a biomarker for brain tumor malignancy. Glycine is a component of a nutrients mixture for peripheral administration to well-nourished mildly catabolic adult patients who require only short-term parenteral nutrition.

Tiamenidine (also known as HOE 440) is a diazacycloalkene derivative patented by Farbwerke Hoechst A.-G. as 2 alpha-sympathomimetic antihypertensive agents. In preclinical models, tiamenidine induces hypotension and bradycardia in renal hypertensive cats and rats and in normal rats and dogs. Furthermore, Tiamenidine inhibits the liberation of norepinephrine from nerves leading to the heart and suppress sympathetic circulatory reflexes in dogs. In clinical trials, Tiamenidine exerts favor influences on systolic and diastolic blood pressure, and reduces plasma noradrenaline and adrenaline levels and suppresses plasma renin activity. Unfortunately, during the withdrawal of Tiamenidine, there is a rebound of blood pressure and plasma noradrenaline and adrenaline, overshooting baseline levels.

Efaroxan (RX 821037) is a potent and selective alpha(2)-adrenoceptor antagonist. Additionally, Efaroxan is a selective antagonist at the imidazoline I1 receptor. Efaroxan promotes insulin secretion, in the absence of exogenous agonists, by a mechanism that involves inhibition of ATP-regulated K+ channels. Efaroxan was in clinical trials for the treatment of diabetes mellitus however its development has been discontinued.

Cirazoline is an agonist of alpha1A adrenergic receptor, a partial agonist of alpha1B and alpha1D receptors, and an antagonist of alpha2 adrenergic receptors. Cirazoline was used to study the biologic function of adrenergic receptors. Injection of cirazoline into to the paravenricular hypothalamic nucleus of rats suppressed food and water intake. Cirazoline caused a large renal vasopressor response in rats. Systemic administration of cirazoline impaired spatial working memory in monkeys.