Racepinephrine

Racepinephrine is a racemic mixture consisting of d-Epinephrine and l-Epinephrine enantiomers. Epinephrine is a non-selective α- and β-adrenergic receptor agonist. It is a bronchodilator used in the temporary relief of mild symptoms of intermittent asthma including wheezing, tightness of chest and shortness of breath. It is an active ingredient in oral inhalation over-the-counter products as racepinephrine hydrochloride.

Racepinephrine is a bronchodilator used to treat intermittent asthma.

Indicated for temporary relief of mild symptoms of intermittent asthma.

• Asthma

Epinephrine acts on α- and β-adrenergic receptors. When given subcutaneously or intramuscularly, epinephrine has a rapid onset and short duration of action . Epinephrine induces bronchial smooth muscle relaxation to relieve respiratory distress in asthma. In a clinical trial of paediatric patients with bronchiolitis, administration of aerosolized racemic epinephrine via inhalation resulted in improved clinical symptoms such as wheezing and retractions . The clinical efficacy of racemic epinephrine was comparable to that of salbutamol or albuterol, which are commonly used bronchodilators .

Epinephrine is a non-selective agonist at α- and β-adrenergic receptors, which are all G-protein-coupled receptors. The main therapeutic effect of epinephrine arises from its agonist action on β2-adrenergic receptors, which activate adenylyl cyclase and increase intracellular cyclic AMP production. Epinephrine causes smooth muscle relaxation on various tissues, including bronchial smooth muscles . As a result, epinephrine serves to alleviate bronchospasm, wheezing and tightness of chest that may occur during asthmatic attacks . Via its relaxer effects on the smooth muscle of the stomach, intestine, uterus and urinary bladder, epinephrine may also alleviate pruritus, urticaria, and angioedema and may relieve gastrointestinal and genitourinary symptoms associated with anaphylaxis.

Epinephrine also acts on the α-adrenergic receptors on vascular smooth muscles, particularly in the skin and splanchnic vascular beds, to cause constriction. Epinephrine is thought to reduce capillary leakage by constricting precapillary arterioles, reducing hydrostatic pressure and consequently bronchial mucosal edema .

To refer to the pharmacokinetic data of L-epinephrine, refer to the drug entry for Epinephrine.

To refer to the pharmacokinetic data of L-epinephrine, refer to the drug entry for Epinephrine.

To refer to the pharmacokinetic data of L-epinephrine, refer to the drug entry for Epinephrine.

To refer to the pharmacokinetic data of L-epinephrine, refer to the drug entry for Epinephrine.

To refer to the pharmacokinetic data of L-epinephrine, refer to the drug entry for Epinephrine.

To refer to the pharmacokinetic data of L-epinephrine, refer to the drug entry for Epinephrine.

Oral LD50 of racepinephrine hydrochloride in mouse is 90 mg/kg .

Overdosage of epinephrine may cause extremely elevated arterial pressure, which may further lead to cerebrovascular hemorrhage, particularly in elderly patients. Peripheral vascular constriction in conjunction with cardiac stimulation may produce pulmonary oedema. Treatment consists of rapidly acting vasodilators or alpha-adrenergic blocking drugs and/or respiratory support. Transient bradycardia followed by tachycardia may also be observed, and may be accompanied by potentially fatal cardiac arrhythmias. remature ventricular contractions may appear within one minute after injection and may be followed by multifocal ventricular tachycardia (prefibrillation rhythm). Subsidence of the ventricular effects may be followed by atrial tachycardia and occasionally by atrioventricular block. In case of arrhythmias, treatment should involve administration of a beta­ adrenergic blocking drug such as propranolol. Overdosage may also produce extreme pallor and coldness of the skin, metabolic acidosis, and kidney failure, which should each be treated with suitable corrective measures .

• Avoid caffeine.

• Jet Nebulizer: Nebulisation for fifteen minutes every 3 to 4 hours. One 0.5 ml ampoule should be diluted to a volume of 3 to 5 ml with sterile 0.9% sodium chloride solution.
• Hand-held Bulb Nebulizer: 1 to 3 inhalations not more often than every 3 hours. The racepinephrine inhalation solution does not require dilution. Should not use more than 12 inhalations in 24 hours.