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.