Drug Interactions
"Definition
A drug interaction refers to the possibility that one drug may alter the pharmacological effects of another drug given concurrently. The net result may be enhanced or diminished effects of one or both of the drugs or a new effect that is not seen with either drug alone.
Commonly Described Drug Interaction
Alcohol
Cimetidine
Metoprolol
Molindone
Medicines for anxiety or sleeping problems, such as diazepam or alprazolam
Medicines for mental depression
Medicines for mental problems or psychotic disturbances
Phenytoin
Pimozide
Warfarin
How Common is it?
Estimates of the incidence of drug-drug interactions, prescription drug interactions and over the counter medications have been reported as high as 20% of patients, who are on more than 5 medications at a time (polypharmacy).
Factors Affecting Drug Metabolism
Prescription drug interactions involving drug metabolism can increase or decrease the amount of drug available for action by inhibition or induction of metabolism Interactions may occur among administered drugs, or between drugs, dietary substances, and industrial chemical exposures such as solvents used in degreasing, painting, and
metal processing.
What Drugs Are Most Likely to be Involved in Drug Interaction?
P450 Inhibitors (Location - Liver) HIV Protease inhibitors Macrolide antibiotics Azole antifungals Non-nucleoside reverse transcriptase inhibitors H2Antogonists
P450 Inducers (Location - Liver) Rifamycin antibiotics HIV Protease inhibitors Non-nucleoside reverse transcriptase inhibitors Anticonvulsants (that are P450 inducers)
Metabolized Drugs with Narrow Therapeutic Indices Non-sedating antihistamines Long-acting opiate analgesics Antiarrhythmics Long-acting benzodiazepines Ergotamines and dihydroergotamine Illicit drugs Coumarin anticoagulants Oral Contraceptives.For more details go to www.environmentaldiseases.com.
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About the Author
"Dr. Nachman Brautbar is a board-certified internist and nephrologist, with a specialization in toxicology. His list of past and present academic appointments include: Associate Professor of Pharmacology and Clinical Professor of Medicine at the University of Southern California, School of Medicine. He specializes in the toxicological and internal medicine aspects of injury in the workplace, product liability, personal injury, standard of
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