Term
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Definition
- An interference of a drug with the effect of another drug, nutrient, or laboratory test.
- Usually the result of taking more than one drug concurrently
- can occur during liberation, absorption, distribution, biotransformation, or excretion
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Term
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Definition
- Two or more drugs working together to produce a stronger effect than expected for each drug taken alone
- Ex. the combination of warfarin sodium with aspirin, which causes excessive risk of blood hemorrhage
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Term
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Definition
- one drug prolongs the effects of another drug
- Is often desirable in order to build up a sufficient drug level or to prolong its effect
- Ex. toxicity caused when cimetidine is combined with asthma medications containing theophylline
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Term
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Definition
- when two drugs decrease the effects of each other
- Ex. When ibuprofen and aspirin are taken together; they stop each other’s action
- Tetracycline and antacids should not be used together, tetracycline must be absorbed in the stomach and antacids inhibit absorption
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Term
| Multiple Pharmacological Effects |
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Definition
- Many drugs used in current therapy can influence many physiological systems
- Ex. combining antipsychotics, antidepressants, and antiparkisonians may cause an unanticipated additive anticholinergic effect
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Term
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Definition
- deliberately misuse drugs may experience increased drug interactions
- Opioids, barbiturates, analgesics, and amphetamines are among the agents most often abused
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Term
| Patient Variables Affecting Drug Interaction |
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Definition
- Age
- Genetic factors
- Diseases and conditions
- Diet
- Alcohol consumption
- Smoking
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Term
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Definition
- Young and elderly patients share an increased incidence of adverse drug reaction potential
- Cytochrome P-450 (enzymes) contribute to many drug interactions in newborns
- Elderly patients’ illnesses and slowing of renal function increases interactions
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Term
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Definition
- Impaired renal and hepatic function are the most important conditions that can alter drug activity
- Renal and hepatic diseases influence patient responses to certain drugs
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Term
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Definition
- Food can affect the absorption of drugs from the GI tract
- Ex. many antibiotics should be given at least 1 hour before, or 2 hours after meals, to achieve optimal absorption
- Grapefruit juice interacts with estrogens, cyclosporine, midazolam, triazolam, and all calcium channel blockers
- toxicity of some drugs (such as MAO inhibitors) increases when they interact with wine, cheese, or yogurt
- CNS-stimulating medications may cause toxicity if combined with caffeine
- Potassium-sparing diuretics and salt substitutes can cause dangerously high blood potassium levels
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Term
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Definition
- Chronic use of alcohol may affect metabolism of drugs such as warfarin, phenytoin, and tolbutamide
- Alcohol used concurrently with sedatives and depressants can result in excessive depressant response
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Term
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Definition
- Smoking increases the activity of drug-metabolizing liver enzymes
- This can decrease effects of diazepam, theophylline, chlorpromazine, and amitriptyline
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Term
| Reducing Risk of Drug Interactions |
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Definition
- Identify patient risk factors such as age, medical condition, diet, smoking, alcohol use
- Accurate patient drug history should be obtained
- Knowledge of drug actions is essential to assess drug interactions
- Consider therapeutic alternatives to using drugs that can interact
- Refrain from administering complex therapeutic regimens and keep number of medications to a minimum
- Educate patients about their illnesses and benefits and risks of their drug therapy
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