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. "