A common mechanism of drug interaction is altered drug pharma-cokinetics with a resultant change in drug concentrations. Many interactions are attributed to altered drug pharmacokinetics, primarily elimination. On the other hand, a pharmacodynamic drug interaction can occur without any changes in drug concentrations, as a result of changes to the pharmacological action of the drug affected. The change can be either an additive or synergistic pharmacological effect, or an antagonistic pharmacological effect.
The following case report describes a likely pharmacodynamic interaction between mirtazapine (Remeron) and clonidine (Catapres), resulting in a loss of blood pressure control.
Shortness of breath common
A 20-year-old patient …