Methamphetamine, a highly addictive synthetic sympathomimetic, has again become important as a drug of abuse in the US. Its resurgence has been associated with unsafe sexual practices that have resulted in an increase in HIV transmission, particularly among men who have sex with men (SJ Semple et al, J Subst Abuse Treat 2002; 22:149; A Urbina and K Jones, Clin Infect Dis 2004; 38:890).

The FDA has approved istradefylline (Nourianz — Kyowa Kirin), an oral adenosine A_2A receptor antagonist, for use as an adjunct to carbidopa/levodopa in adults with Parkinson's disease (PD) who experience "off" episodes. Istradefylline is the first adenosine A_2A receptor antagonist to be approved in the US; it has been available in Japan since 2013.

Fenoldopam mesylte (Corlopam - Neurex), a peripheral dopamine-1 (DA₁) agonist, has been approved by the FDA for parenteral use in lowering blood pressure. The manufacturer claims that, unlike other parenteral antihypertensive agents, fenoldopam not only lowers blood pressure but also maintains or improves renal function.

Aripiprazole (Abilify - Bristol-Myers Squibb/Otsuka), a second-generation (atypical) antipsychotic drug, was approved by the FDA in 2002 for treatment of schizophrenia and more recently for bipolar disorder as well. It has been promoted as causing fewer adverse effects than other antipsychotics, without sacrificing efficacy.

Many fermented foods contain tyramine as a byproduct formed by the bacterial breakdown of the amino acid tyrosine; it can also be formed by para-hydroxylation of phenylethylamine or dehydroxylation of DOPA and dopamine. Tyramine and some other amines found in food can cause hypertensive reactions in patients taking monoamine oxidase (MAO)inhibitors.

The FDA has approved Gimoti (Evoke), a nasal spray formulation of the dopamine-2 (D₂) receptor antagonist metoclopramide, for relief of symptoms in adults with acute and recurrent diabetic gastroparesis. Metoclopramide (Reglan, and generics) has been available for years in conventional and orally-disintegrating tablets and in an injectable formulation. It is the only drug that is FDA-approved for treatment of diabetic gastroparesis.

Gamma hydroxy butyrate (GHB) sold in health food stores has recently caused outbreaks of gastrointestinal illness, central-nervous-system (CNS) depression, and seizures.

Asenapine (Saphris - Schering-Plough), a dibenzo-oxepino pyrrole, has been approved by the FDA in a sublingual tablet formulation for acute treatment of schizophrenia and manic or mixed episodes associated with bipolar disorder. It is the sixth second-generation antipsychotic approved by the FDA for use in bipolar disorder.

The FDA has approved cariprazine (Vraylar – Actavis), an oral, once-daily, second-generation antipsychotic, for treatment of schizophrenia and for acute treatment of manic or mixed episodes associated with bipolar I disorder.

Many readers have asked the Medical Letter to evaluate St. John's wort, an herbal extract now widely sold in health food stores and pharmacies, for its effectiveness and safety in the treatment of depression. St. John's wort is licensed in Germany for treatment of anxiety, depression and insomnia. In the USA, it is considered a dietary supplement and has not been evaluated by the FDA.