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U.S. Department of Health and Human Services

Safety

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Calan (verapamil hydrochloride) tablets

Detailed View: Safety Labeling Changes Approved By FDA Center for Drug Evaluation and Research (CDER) -- July 2009 and June 2011
  

June 2011

Summary View  

 

PRECAUTIONS

Use in patients with attenuated (decreased) neuromuscular transmission
  • and causes a worsening of myasthenia gravis
Drug Interactions
  • Cytochrome inducers/inhibitors: In vitro metabolic studies indicate that verapamil is metabolized by cytochrome P450 CYP3A4, CYP1A2, CYP2C8, CYP2C9 and CYP2C18. Clinically significant interactions have been reported with inhibitors of CYP3A4 (e.g., erythromycin, ritonavir) causing elevation of plasma levels of verapamil while inducers of CYP3A4 (e.g., rifampin) have caused a lowering of plasma levels of verapamil.
  • Aspirin: In a few reported cases, co-administration of verapamil with aspirin has led to increased bleeding times greater than observed with aspirin alone.
  • Grapefruit juice: Grapefruit juice may increase plasma levels of verapamil.

ADVERSE REACTIONS

Nervous system
  • extrapyramidal symptoms

 

July 2009

Summary View

The detailed view includes drug products with safety labeling changes to the BOXED WARNING, CONTRAINDICATIONS, WARNINGS, PRECAUTIONS, ADVERSE REACTIONS, or PATIENT PACKAGE INSERT/MEDICATION GUIDE sections. Deletions or editorial revisions made to these sections are not included in this summary.

 

PRECAUTIONS

Drug interactions/Other agents
  • Telithromycin: Hypotension and bradyarrhythmias have been observed in patients receiving concurrent telithromycin, an antibiotic in the ketolide class.