The FDA has issued new warnings about the use of the opioid analgesics codeine and tramadol in children, particularly those <12 years old, and in breastfeeding women due to concerns about the risk of respiratory depression and death. The FDA previously issued warnings about these drugs in 2013 and 2015.

Tramadol hydrochloride (Ultram - Ortho-McNeil), a centrally-acting analgesic marketed in Germany since 1977, was recently approved by the US Food and Drug Administration for oral treatment of moderate to moderately severe pain. Despite some opioid activity, tramadol has not been scheduled as a controlled substance.

The FDA has approved an effervescent tablet formulation of acetylcysteine (Cetylev – Arbor) to prevent or lessen hepatic injury after acetaminophen overdose. Acetylcysteine has been available for years in an IV solution (Acetadote, and generics) and an oral solution for the same indication; use of the oral solution has been limited by its unpleasant odor and taste.

Rimantadine hydrochloride (Flumadine - Forest), the alpha-methyl derivative of amantadine (Symmetrel, and others), was recently approved by the US Food and Drug Administration for prevention and treatment of influenza A virus infections in adults and for prevention of influenza in children.

With the removal of Vioxx from the market and concerns about cardiovascular toxicity with other selective COX-2 inhibitors, patients are looking for safe alternatives, and manufacturers of other drugs are looking for additional market share. The COX-2 inhibitors first became popular because they have less upper GI toxicity than older less selective NSAIDs, at least in the short term, in patients not taking aspirin.

Acetaminophen (paracetamol; Tylenol, and others) taken in overdosage can cause severe hepatic injury and death. Acetaminophen poisoning is treated with (N-)acetylcysteine. Available for many years in the US as a solution for inhalation therapy (Mucomyst, and others), it subsequently became available for oral use and was recently marketed in the US for intravenous (IV) use as Acetadote (Cumberland).

Diclofenac epolamine patch 1.3% (Flector Patch - Alpharma), a topical formulation of the nonsteroidal anti-inflammatory drug (NSAID) diclofenac, has been approved by the FDA for topical treatment of acute pain due to minor strains, sprains and contusions. It is the first topical NSAID patch approved in the US. A diclofenac patch has been used in Europe since 1993. Diclofenac sodium (Voltaren, and others) is available in the US as an oral tablet, in a 1% gel for treatment of osteoarthritis (to be reviewed in a future issue), in a 3% gel (Solaraze) for treatment of actinic keratoses, and in an...

immune globulin (human) has been available for many years in an intramuscular (IM) formulation for prevention of Rh isoimmunization in pregnant Rh-negative women (Medical Letter, 16:3, 1974). Recently, the US Food and Drug Administration (FDA) approved the first intravenous (IV) immune globulin preparation (WinRho SD - Univax), not only for preventing Rh isoimmunization, but also for treatment of immune thrombocytopenic purpura (ITP) in Rh-positive patients.

Gabapentin (Neurontin - Pfizer), which has been available in the US since 1994, is approved by the FDA only for treatment of partial epilepsy and postherpetic neuralgia, but is widely used off-label for a number of other indications, especially neuropathic pain syndromes. According to one report, among Medicaid recipients in Florida receiving gabapentin, 71% of prescriptions were for chronic pain and 8% for seizures and neuralgia ("The Pink Sheet" February 2, 2004; 66:30).

Warfarin sodium (Coumadin, and others) and other coumarin anticoagulants prevent thrombosis, but patient response is highly variable and overanticoagulation can lead to hemorrhage. Genotyping patients for single nucleotide polymorphisms (SNPs) that affect coumarin metabolism and sensitivity may help clinicians estimate the therapeutic warfarin dose. The FDA has added a note to warfarin labeling recommending lowrange doses for patients with such genetic variations. Commercial tests for these variants are now available and cost about $500 per test.