Levosalbutamol

Medical use

Levosalbutamol is indicated for bronchospasm treatment or prevention in people aged four and older with reversible obstructive airway disease. Evidence comparing its efficacy to salbutamol or combinations is inconclusive, though it is thought to have a better safety profile due to more selective β2 receptor binding. A systematic review found it not superior to albuterol for acute asthma and suggested it should not be used over albuterol.

Adverse effects

Levosalbutamol is generally well tolerated. Common mild effects include elevated heart rate, muscle cramps, and gastric upset such as heartburn or diarrhea. Overdose symptoms may include seizure, chest pain, fast or irregular heartbeat, hypertension or hypotension, nervousness, tremor, headache, dizziness, nausea, weakness, dry mouth, and insomnia. Rare allergic reactions include paradoxical bronchospasm, itching, rash, hives, and swelling of the face, throat, or extremities.

Pharmacology

Activation of β2 adrenergic receptors on airway smooth muscle stimulates adenylate cyclase, increasing intracellular cyclic AMP. This activates protein kinase A, which inhibits myosin phosphorylation and lowers intracellular calcium, causing muscle relaxation. Levosalbutamol relaxes smooth muscles from the trachea to terminal bronchioles and inhibits mast cell mediator release. It acts as a functional agonist against any bronchoconstrictor.

Although β2 receptors predominate in bronchial muscle, 10–50% of heart beta receptors are β2; all β-adrenergic agonists can cause cardiovascular effects. Levosalbutamol and salbutamol do not racemize significantly before elimination. Enantiomerically pure levosalbutamol is preferred over racemic salbutamol because S-salbutamol has negative side effects.

Society and culture

Levalbuterol, also known internationally as levosalbutamol, costs more than standard salbutamol. It was approved in the US as a nebulizer solution in March 1999, with a metered-dose inhaler version (Xopenex HFA) following in March 2005. The World Anti-Doping Agency bans this drug. In Bangladesh, it is sold as Purisal.