Adverse Drug Reactions in the Elderly

Can We Stem the Tide?

Shari J. Lynn


Am Nurs Journal. 2012;7(1) 

In This Article

Drug Interactions: Pharmacokinetic vs Pharmacodynamic

Drug interactions can be pharmacokinetic or pharmacodynamic.

  • With a pharmacokinetic interaction, one drug affects the other's absorption, distribution, metabolism, or excretion. An example occurs when a patient takes the antibiotic ciprofloxacin with olanzapine, a drug used to treat schizophrenia. Ciprofloxacin blocks the enzyme that breaks down olanzapine; this results in high blood levels of olanzapine, which in turn may cause muscle spasms and predispose the patient to falls.

  • In a pharmacodynamic interaction, two drugs have additive or antagonistic effects. For example, if ciprofloxacin is given with glibenclamide (an antidiabetic), it may increase the antidiabetic effects of glibenclamide, possibly causing profound hypoglycemia.


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