The FDA recently cleared the AmpliChip CYP450 Test (Roche), which analyzes blood-derived DNA to detect genetic variations in the activity of cytochrome P450 (CYP) enzymes CYP2D6 and CYP2C19 and determines the metabolizer status of the patient. The test is intended to help guide clinicians in prescribing individualized drug therapy. About 25% of all drugs, including many antidepressants and antipsychotics, are substrates of either CYP2D6 or CYP2C19. The test is being promoted initially to psychiatrists.

Pantoprazole, the fourth benzimidazole proton pump inhibitor to become available in the United States, has been marketed for short-term oral treatment of erosive gastroesophageal reflux disease (GERD).

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).

The FDA has approved the proton-pump inhibitor (PPI) dexlansoprazole (Kapidex - Takeda), a delayed release formulation of the R-enantiomer of lansoprazole (Prevacid - Takeda), for treating and maintaining healing of erosive esophagitis and for treatment of heartburn associated with non-erosive gastroesophageal reflux disease (GERD).

Anxiety disorders (generalized anxiety disorder, panic disorder, social anxiety disorder, and various phobias) are the most common form of psychiatric illness. They can be treated effectively with cognitive behavioral therapy (CBT) and/or pharmacotherapy.

The FDA recently approved the proton pump inhibitor omeprazole magnesium (Prilosec OTC) for over-the-counter use for treatment of frequent heartburn. It will be marketed in late September or early October. Five proton pump inhibitors, including omeprazole, are available by prescription in the US (Medical Letter 2001; 43:36).

An article published in the New York Times on May 1, 2015 listed the 10 drugs on which Medicare Part D spent the most in 2013. The most costly ($2.53 billion) was the proton pump inhibitor (PPI) Nexium (esomeprazole magnesium), which has recently become available generically.

Omeprazole (Losec - Merck), a new drug that suppresses gastric acid secretion, has been approved by the US Food and Drug Administration for short-term (four to eight weeks) treatment of severe or refractory gastroesophageal reflux and for long-term treatment of pathological hypersecretory conditions such as Zollinger-Ellison syndrome, multiple endocrine adenomas, and systemic mastocytosis. Although widely used abroad for treatment of peptic ulcers, it has not been approved for that indication in the USA.

Cisapride (Propulsid - Janssen), a piperidinyl benzamide prokinetic drug, is now available in the USA for symptomatic relief of nocturnal heartburn due to gastroesophageal reflux disease. In Canada, cisapride is also marketed for treatment of gastroparesis.