Phenylpropanolamine belongs to the sympathomimetic amine class of drugs and is structurally related to ephedrine. The effects of phenylpropanolamine are largely the result of alpha-adrenergic agonist activity resulting from both direct stimulation of adrenergic receptors and release of neuronal norepinephrine. Phenylpropanolamine is mainly used as a nasal decongestant. Phenylpropanolamine is also used as anorexiant in obesity and to treat urinary incontinence in veteranary. Phenylpropanolamine containing products has been withdrawn by FDA due to the association of phenylpropanolamine use with increased risk of hemorrhagic stroke.

Oxedrine (Sympatol, p-synephrine) is a naturally occurring alkaloid molecule first appeared in Europe towards the end of the 1920s being sold as a drug under the brand name Sympatol. Oxedrine was then being prescribed as a remedy for a number of respiratory conditions, which include asthma, whooping cough, colds, and hay fever. More recently, synephrine gained popularity as a weight loss aid and it has become a favored component in the more popular brands of weight loss supplement stacks. This popularity can be attributed in part to the ban imposed on ephedra, to which it shares similar mechanisms of action. Most, if not all of the synephrine being sold as a dietary supplement is extracted and synthesized from the Citrus aurantium plant, more commonly known as bitter orange. Just like ephedrine, synephrine has vasoconstrictive abilities, although at a lesser potency compared to ephedrine. There is no mention of synephrine in editions of Drill's Pharmacology in Medicine later than the 3rd, nor is there any reference to synephrine in the 2012 Physicians' Desk Reference, nor in the current FDA "Orange Book". One current reference source describes synephrine as a vasoconstrictor that has been given to hypotensive patients, orally or by injection, in doses of 20–100 mg.

Oxedrine (Sympatol, p-synephrine) is a naturally occurring alkaloid molecule first appeared in Europe towards the end of the 1920s being sold as a drug under the brand name Sympatol. Oxedrine was then being prescribed as a remedy for a number of respiratory conditions, which include asthma, whooping cough, colds, and hay fever. More recently, synephrine gained popularity as a weight loss aid and it has become a favored component in the more popular brands of weight loss supplement stacks. This popularity can be attributed in part to the ban imposed on ephedra, to which it shares similar mechanisms of action. Most, if not all of the synephrine being sold as a dietary supplement is extracted and synthesized from the Citrus aurantium plant, more commonly known as bitter orange. Just like ephedrine, synephrine has vasoconstrictive abilities, although at a lesser potency compared to ephedrine. There is no mention of synephrine in editions of Drill's Pharmacology in Medicine later than the 3rd, nor is there any reference to synephrine in the 2012 Physicians' Desk Reference, nor in the current FDA "Orange Book". One current reference source describes synephrine as a vasoconstrictor that has been given to hypotensive patients, orally or by injection, in doses of 20–100 mg.

Oxedrine (Sympatol, p-synephrine) is a naturally occurring alkaloid molecule first appeared in Europe towards the end of the 1920s being sold as a drug under the brand name Sympatol. Oxedrine was then being prescribed as a remedy for a number of respiratory conditions, which include asthma, whooping cough, colds, and hay fever. More recently, synephrine gained popularity as a weight loss aid and it has become a favored component in the more popular brands of weight loss supplement stacks. This popularity can be attributed in part to the ban imposed on ephedra, to which it shares similar mechanisms of action. Most, if not all of the synephrine being sold as a dietary supplement is extracted and synthesized from the Citrus aurantium plant, more commonly known as bitter orange. Just like ephedrine, synephrine has vasoconstrictive abilities, although at a lesser potency compared to ephedrine. There is no mention of synephrine in editions of Drill's Pharmacology in Medicine later than the 3rd, nor is there any reference to synephrine in the 2012 Physicians' Desk Reference, nor in the current FDA "Orange Book". One current reference source describes synephrine as a vasoconstrictor that has been given to hypotensive patients, orally or by injection, in doses of 20–100 mg.

Nicergoline is a semisynthetic ergoline derivative that has been used as a cerebral vasodilator and in peripheral vascular disease. Nicergoline seems to have an action: (i) as an alpha1-adrenoceptor antagonist, it induces vasodilation and increases arterial blood flow; (ii) it enhances cholinergic and catecholaminergic neurotransmitter function; (iii) it inhibits platelet aggregation; (iv) it promotes metabolic activity, resulting in increased utilization of oxygen and glucose; and (v) it has neurotrophic and antioxidant properties. Nicergoline has been suggested to ameliorate cognitive deficits in cerebrovascular disease.

Indoramin is an alpha-1 selective antagonist of adrenergic receptor, sold under trade names Baratol and Doralese, and now available as a generic. It has no reflex tachycardia and direct myocardial depression action and is used to treat benign prostate hyperplasia (as 20 mg tablets) or reduce blood pressure (as 25 mg strength tablets). It was also investigated as a treatment of a migraine and congestive heart failure.