Psychotropic drug interactions in the patient with late-onset psychosis and mood disorder. Part 1.

We have discussed major drug interactions involving neuroleptics and MAOIs. Interactions in the older patients are probably more frequent owing to the larger number of medications used. When interactions do occur in the elderly, the effects may be more severe and of a longer duration than those seen in younger patients. Many (but not all) drug-drug interactions are predictable, given a basic knowledge of the pharmacologic effects of the agents in question. In a number of cases, there are therapeutic alternatives to agents that have been reported to interact with psychotropic medications. The clinician should consider the likelihood of adverse drug interactions to be a significant concern as the age of the patient and the number of concurrently administered medications increase.

Psychotropic drug interactions in the patient with late-onset depression or psychosis. Part 2.

We now conclude our discussion of psychotropic drug interactions in the late-life depression or psychosis patient. We have attempted to point out the more common drug interactions, while also mentioning less well-reported, yet potentially important interactions. The outcome of such adverse reactions as we have described herein is usually of greater concern in older patients. Accordingly, this population would benefit considerably from accurate reporting of any suspected drug interactions. Although most drug interactions are usually somewhat predictable, it is very important that those interactions that are not expected otherwise be well documented. As stated elsewhere in this review, a good basic knowledge of the pharmacology of the agents in question will serve the clinician and his or her patient well.

Evaluation of appropriateness and interpretation of serum theophylline assays.

A drug utilization review of serum theophylline assays was undertaken to: (1) evaluate the prescribers' usage and interpretation of serum theophylline levels (STLs), and (2) calculate the cost of inappropriate assays. Criteria for appropriate use and interpretation were defined by an audit committee and approved by the chief medical resident. STLs were evaluated on medicine patients for a one-month period. Results of 102 levels ordered showed that 47 percent were inappropriate. The reasons cited most often for inappropriateness were: (1) previously-known STLs with no reason to expect a change in subsequent levels (26 percent); and (2) STLs drawn prior to steady state (12 percent). None of the levels evaluated had a request entered for the sampling time to be recorded. STLs were interpreted with the same degree of accuracy regardless of whether they were ordered appropriately. Results from this study suggest significant cost savings can be realized if physicians' ordering habits are corrected.