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Label Changes for:

Dilantin (phenytoin) Oral Suspension

November 2011

Changes have been made to the CONTRAINDICATIONS, WARNINGS, PRECAUTIONS and ADVERSE REACTIONS sections of the safety label.

Detailed View: Safety Labeling Changes Approved By FDA Center for Drug Evaluation and Research (CDER) – November 2011



Hypersensitivity to inactive ingredients
  • Coadministration of Dilantin is contraindicated with delavirdine due to potential for loss of virologic response and possible resistance to delavirdine or to the class of non-nucleoside reverse transcriptase inhibitors.


Drug Reaction with Eosinophilia and Systemic Symptoms (DRESS)/Multiorgan hypersensitivity
  • Drug Reaction with Eosinophilia and Systemic Symptoms (DRESS), also known as Multiorgan hypersensitivity, has been reported in patients taking antiepileptic drugs, including Dilantin. Some of these events have been fatal or life-threatening. DRESS typically, although not exclusively ….
Effects on Vitamin D and Bone
  • The chronic use of phenytoin in patients with epilepsy has been associated with decreased bone mineral density (osteopenia, osteoporosis, and osteomalacia) and bone fractures. ...


  • Phenytoin is extensively bound to serum plasma proteins and is prone to competitive displacement. Phenytoin is metabolized by hepatic cytochrome P450 enzymes and is particularly susceptible to inhibitory drug interactions because it is subject to saturable metabolism. Inhibition of metabolism may produce significant increases in circulating phenytoin concentrations and enhance the risk of drug toxicity. Phenytoin is a potent inducer of hepatic drug-metabolizing enzymes
  • Drugs that should not be used concurrently with phenytoin: Delavirdine.
  • Drugs which may increase phenytoin serum levels include: fluvoxamine,fluorouracil, omeprazole, sertraline, warfarin.
  • Drugs that may decrease plasma phenytoin concentrations include nelfinavir, ritonavir
  • Drugs whose efficacy is impaired by phenytoin include: azoles (ketoconazole, itraconazole, voriconazole),sertraline,teniposide,irinotecan,paclitaxel, warfarin
  • Phenytoin decreases plasma concentrations of certain HIV antivirals (amprenavir, efavirenz,Kaletra(lopinavir/ritonavir), indinavir, nelfinavir, ritonavir, saquinavir), and anti-epileptic agents (felbamate, topiramate, oxcarbazepine, quetiapine). Addition or withdrawal of phenytoin during concomitant therapy with these agents may require adjustment of the dose of these agents


  • Body as a Whole: Allergic reactions in the form of rash and rarely more serious forms (see Skin and Appendages paragraph below) and DRESS (see Warnings section) have been observed. Anaphylaxis has also been reported.
  • There have also been reports of coarsening of facial features, systemic lupus erythematosus, periarteritis nodosa, and mmunoglobulin abnormalities.
  • Central Nervous System: paresthesia, somnolence,
  • Digestive System: enlargement of the lips, gingival hyperplasia,
  • Skin and Appendages:There have also been reports of hypertrichosis.
  • Special Senses: Altered taste sensation including metallic taste.
  • Urogenital: Peyronie’s disease