PHARMACOKINETIC SCREENING METHODOLOGY FOR EVALUATING DRUGS IN ELDERLY PATIENTS COULD BE DEVELOPED BY FDA/INDUSTRY/ACADEMIA, WORKSHOP GROUP SAYS

A pharmacokinetic screening methodology for new drug evaluation in elderly patients should be developed cooperatively by the pharmaceutical industry, FDA, and academia, a workshop panel considering FDA proposed guidelines for testing of drugs in the elderly recommended. The American Society of Clinical Pharmacology & Therapeutics and FDA sponsored the meeting, held in Washington, D.C. Sept. 13-14. While concluding that "no definitive recommendations" for a screening methodology can be made at this time, a panel of specialists said: "Rather, it is recommended that the practical feasibility of the various pharmacokinetic extremes in new drug development be evaluated in a prospective fashion prior to possible implementation of any design into regulatory guidelines." "Whereas the scientific design of such an evaluation is readily definable, the means by which it could be accomplished may provide the development of new and imaginative relationships and interactions between the pharmaceutical industry, FDA and academia," the panel continued. "Indeed, it would be preferable if such feasibility testing were carried out as a cooperative venture involving design, analysis and evaluation" between the three groups. FDA's proposed guidelines, circulated as a discussion paper in September 1983, called for the addition of a pharmacokinetic screen -- "a small number of blood level determinations during steady state dosing" -- to NDA submissions. The agency explained that the screen would be a means of determining a drug's potential for "unanticipated problems." A separate panel, led by Gilbert McMahon, MD, Tulane University, made recommendations on the conduct of clinical trials. "Since many, if not most drugs are extensively used in patients in the geriatric age group, it is highly desirable, whenever possible, to include a reasonable sample of patients over 65 in Phase II and Phase III studies," the panel stated. "Depending on the early findings" of these studies, "it may be desirable to design intensive pharmacokinetic and pharmacodynamic studies aimed at specifically investigating age differences Such studies "may include healthy elderly volunteers as well as selected groups of geriatric patients, for example, patients with altered renal or hepatic or cognitive function," the panel explained. (NEW LINE) "Real World Protocol" Comparing Test v. Control Drugs In Elderly Proposed By Workshop Panel In an earlier discussion, the panel suggested that "a new type of study be undertaken routinely with all drugs that are preferentially used in elderly patients." McMahon said the study, characterized as a "real world protocol," would involve a comparison of 200 patients over 65 who were administered the test drug to 200 patients over 65 receiving a control drug. Duration of the study would be two to three months and include patients on concommitant medications with concurrent diseases. The panel did not include the protocol in their formal recommendations. A panel considering pharmacokinetic studies recommended that "prior to the enrollment of elderly patients in drug efficacy studies, the clinical pharmacokinetic profile of the drug should be determined in a comparably aged group of healthy volunteers." The results of the study "should be analyzed considering the expected decrease in renal elimination with decreased renal function," the panel said. "If unpredicted, clinically important differences are observed, then additional studies may be required to determine the appropriate regimen in this population." The recommendations are to be compiled by the society and formally submitted to FDA. The agency will consider the document in developing its draft guideline for clinical testing of drugs in the elderly.