Evaluation of therapeutic drug monitoring in a long-term care facility: a pilot project.

The need for a therapeutic drug monitoring service was evaluated in a 150-bed long-term care facility. Thirty blood samples from 28 residents (mean age 87.9 years) were assayed to determine trough drug concentrations. All subjects were examined to determine pharmacodynamic effect. Pharmacokinetic consultations were written for serum drug concentrations outside accepted ranges. Fifty percent (15 of 30) of serum drug levels measured were subtherapeutic; the remaining levels were in the normal therapeutic range. Based on this sample data, it could be concluded that a minimum of 32 percent and as many as 68 percent of serum drug levels would be subtherapeutic following drug analysis in similar nursing home populations. Of 12 consultations, recommendations for seven (58 percent) were accepted by the subject's primary care physicians. Four of the consultations (33 percent) resulted in dosage modifications. These results support the need for further study.