A reader expressed concern that a statement in our article Naloxone (Narcan) Nasal Spray for Opioid Overdose (Med Lett Drugs Ther 2016; 58:1) might be misleading. We stated that heroin has a half-life of 2-6 minutes, which is correct, but heroin is a prodrug that is rapidly metabolized to 6-acetylmorphine and morphine. The risk of respiratory depression is related to those active metabolites, and it may persist well beyond the clearance of heroin from the blood.

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 FDA has approved an extended-release fixed-dose combination of dextromethorphan and bupropion (Auvelity – Axsome) for treatment of major depressive disorder (MDD) in adults.

Many drugs can cause psychiatric symptoms, but a causal connection is often difficult to establish. Psychiatric symptoms that emerge during drug treatment could also be due to the underlying illness, previously unrecognized psychopathology, or psychosocial factors. The withdrawal of some drugs can cause symptoms such as anxiety, psychosis, delirium, agitation or depression.

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An oral nonopioid analgesic is often sufficient for acute treatment of mild to moderate migraine pain without severe nausea or vomiting. A triptan is the drug of choice for treatment of moderate to severe migraine in most patients without vascular disease. Treatment of pain when it is still mild to moderate in intensity improves headache response and reduces the risk of recurrence.

The FDA has approved a topical 8% patch formulation of capsaicin (Qutenza – NeurogesX), available only by prescription, for local treatment of postherpetic neuralgia. Postherpetic neuralgia occurs after herpes zoster in about one third of patients ≥60 years old and can persist for months or even years.

The FDA has approved ozanimod (Zeposia – Celgene), a sphingosine 1-phosphate (S1P) receptor modulator, for treatment of adults with relapsing forms of multiple sclerosis (MS), including clinically isolated syndrome (initial neurological episode), relapsing-remitting disease, and active secondary progressive MS (SPMS). It is the third oral S1P receptor modulator to be approved in the US for treatment of relapsing forms of MS; siponimod (Mayzent) is also indicated for use in adults, and fingolimod (Gilenya) is approved for use in patients ≥10 years old.

Alosetron hydrochloride (Lotronex - Glaxo Welcome), a selective serotonin receptor antagonist, has received FDA approval for treatment of irritable bowel syndrome (IBS) in women whose primary bowel symptom is diarrhea.

Odevixibat (Bylvay – Albireo), an oral ileal bile acid transporter (IBAT) inhibitor, has been approved by the FDA for treatment of pruritus in patients ≥3 months old with progressive familial intrahepatic cholestasis (PFIC). It is the first drug to be approved in the US for this indication.

Transdermal fentanyl (Duragesic, and others) offers a convenient delivery system for patients with chronic pain1 but it has some drawbacks. One is that exposing the patch to heat, either from an external source, increased exertion or possibly high fever, could increase release of the drug, which might lead to an overdose and fatal respiratory depression.2 A recent article in the NY Times about this problem may have aroused the concerns of some patients using the patches.3First approved for marketing by the FDA in 19914, transdermal fentanyl provides continuous delivery of the drug for about 3...