Montelukast (Singulair - Merck) is an oral cysteinyl leukotriene D₄ receptor antagonist originally marketed for treatment of asthma. It was approved by the FDA in 2003 for treatment of seasonal allergic rhinitis and recently for use in perennial allergic rhinitis in adults and children ≥ 6 months old. Intranasal corticosteroids have generally been considered the most effective drugs available for prevention and treatment of allergic rhinitis.

The FDA has approved a nasal spray fixed-dose combination (Dymista – Meda) of the H₁-antihistamine azelastine (Astelin, Astepro, and generics) and the corticosteroid fluticasone propionate (Flonase, and generics) for treatment of seasonal allergic rhinitis (SAR) in patients ≥12 years old who need both medications for symptomatic relief. It is the first nasal spray to be approved in the US that contains both an H₁-antihistamine and a corticosteroid.

The FDA has approved an inhaled fixed-dose combination (Breo Ellipta – GSK/Theravance) of the corticosteroid fluticasone furoate and the long-acting beta₂-adrenergic agonist (LABA) vilanterol trifenatate for once-daily treatment of chronic obstructive pulmonary disease (COPD).

Elafibranor (Iqirvo – Ipsen), a peroxisome proliferator-activated receptor (PPAR) agonist, has been granted accelerated approval by the FDA for treatment of primary biliary cholangitis (PBC) in adults. It is indicated for use in combination with ursodeoxycholic acid (ursodiol, UDCA; Urso, and others) in patients with an inadequate response to UDCA alone and as monotherapy in those unable to tolerate UDCA.

Fluticasone furoate nasal spray (Veramyst - GSK) is now available for once-daily treatment of seasonal and perennial allergic rhinitis in adults and children ≥2 years old. It is similar to fluticasone propionate nasal spray (Flonase, and others), which is now available generically.

Montelukast sodium (Singulair - Merck), a leukotriene receptor antagonist, has been approved by the US Food and Drug Administration (FDA) for oral prophylaxis and chronic treatment of asthma in adults and children at least 6 years old. It is the third 'leukotriene modifier' to become available in the USA; zafirlukast (Accolate - Medical Letter, 38:111, 1996) and zileuton (Zyflo - Medical Letter, 39:18, 1997) were marketed previously. Neither zafirlukast nor zileuton has been approved by the FDA for use in children less than 12 years old. Leukotriene modifiers are not recommended for...

The FDA has approved the marketing of the corticosteroid ciclesonide (Alvesco - Sepracor) in a hydrofluoroalkane (HFA) metered-dose inhaler formulation for maintenance treatment of asthma in patients >12 years old. Ciclesonide is also available in the US as a nasal spray for allergic rhinitis (Omnaris), and has been available for asthma in Europe since 2003.

The FDA has approved the over-the-counter (OTC) sale of Nasacort Allergy 24HR (Sanofi), a triamcinolone acetonide nasal spray previously available only by prescription as Nasacort AQ. The OTC product, which is scheduled to be marketed in the spring of 2014, will be the first corticosteroid nasal spray that can be purchased without a prescription in the US. Nasacort Allergy 24HR is approved for use in patients ≥2 years old with nasal allergy symptoms.

Changes caused by one drug in the absorption, distribution, metabolism or excretion of another may lead to a pharmacokinetic adverse drug interaction (DN Juurlink et al, JAMA 2003; 289:1652). Additive drug interactions, such as vasodilation caused by both sildenafil (Viagra) and nitrates, can also have adverse effects.

The ability of grapefruit juice to increase serum concentrations of drugs was first discovered during a study of the effect of ethanol on felodipine (Plendil) pharmacokinetics. Double-strength grapefruit juice used to disguise the taste of ethanol resulted in higher than expected serum concentrations of felodipine (DG Bailey et al, Clin Invest Med 1989; 12:357).