Limited sampling strategy of partial area under the concentration-time curves to estimate midazolam systemic clearance for cytochrome P450 3A phenotyping.

OBJECTIVE: Intravenous (IV) midazolam is the preferred cytochrome P450 (CYP) 3A probe for phenotyping, with systemic clearance (CL) estimating hepatic CYP3A activity. A limited sampling strategy was conducted to determine whether partial area under the concentration-time curves (AUCs) could reliably estimate midazolam systemic CL during conditions of CYP3A baseline activity, inhibition, and induction/activation. METHODS: Midazolam plasma concentrations during CYP3A baseline (n = 93), inhibition (n = 40), and induction/activation (n = 33) were obtained from 7 studies in healthy adults. Noncompartmental analysis determined observed CL (CL(obs)) and partial AUCs. Linear regression equations were derived from partial AUCs to estimate CL (CL(pred)) during CYP3A baseline, inhibition, and induction/activation. Preestablished criterion for linear regression analysis was r(2) ≥ 0.9. CL(pred) was compared with CL(obs), and relative bias and precision were assessed using percent mean prediction error and percent mean absolute error. RESULTS: During CYP3A baseline and inhibition, all evaluated partial AUCs failed to meet criterion of r(2) ≥ 0.9 and/or percent mean absolute error <15%. During CYP3A induction/activation, equations derived from partial AUCs from 0 to 1 hour (AUC0-1), 0 to 2 hours (AUC0-2), and 0 to 4 hours (AUC0-4) were acceptable, with good precision and minimal bias. These equations provided the same conclusions regarding equivalency testing compared with intense sampling. CONCLUSIONS: During CYP3A induction/activation, but not baseline or inhibition, midazolam partial AUC0-1, AUC0-2, and AUC0-4 reliably estimated systemic CL and consequently hepatic CYP3A activity in healthy adults.

Evaluation of a Pharmacist-Managed Antidiabetic Deprescribing Program in an Integrated Health Care System.

BACKGROUND: In the elderly, use of medications may increase the propensity for adverse drug events due to alterations in pharmacokinetic and pharmacodynamic profiles from normal aging processes. Deprescribing is the planned and supervised process of dose reduction or discontinuation of medications that may lead to harm or are no longer beneficial. While there are studies detailing strategies to deprescribe medications such as benzodiazepines and antipsychotics in nursing homes or for patients with dementia, there is a lack of guidance to safely deprescribe chronic medications, such as antidiabetics, for older patients in the community setting. OBJECTIVE: To evaluate the risk of hypoglycemia and other outcomes of pharmacist-managed deprescribing on selected antidiabetic medications under the guidance of a standardized program compared with usual care within an integrated health care system. METHODS: This was a retrospective propensity score-matched cohort study. The pharmacist-managed deprescribing group included patients who were enrolled in the deprescribing program between July 1, 2016, and June 30, 2017. The usual care group included eligible patients who did not receive the deprescribing intervention and were matched to the deprescribing group using propensity score matching (PSM). Baseline demographics and clinical variables were used for matching. Patients were followed for 6 months or the end of membership or death, whichever occurred first. Primary outcome was the risk of hypoglycemia. Secondary outcomes included risk of hyperglycemia, proportion of patients at goal (A1c), change in A1c, change in monthly antidiabetic drug cost, and all-cause mortality. Outcomes were analyzed using descriptive statistics and multivariant regression or Cox proportional hazard models when appropriate. RESULTS: After PSM, 685 patients in the deprescribing group and 2,055 patients in the usual care group were similar in age, gender, weight, and comorbidity burden (mean [SD] age 82.4 [5.4] years, 48% female, mean [SD] weight 81.7 [19.2] kg, mean [SD] Charlson Comorbidity Index score 3.2 [1.6]). Compared with the usual care group, the deprescribing group had a lower risk of hypoglycemia (1.5% vs. 3.1%, P < 0.02; adjusted odds ratio 0.42, P < 0.01). As for the secondary outcomes, the deprescribing group had a greater change (SD) in A1c (0.3 [0.6] vs. 0.2 [0.7] P < 0.01) and lower all-cause mortality (2.3% vs 5.6%, P < 0.01; adjusted hazard ratio 0.35, P < 0.01). There were no differences observed in the risk of hyperglycemia, proportion of patients at goal A1c < 7%, and change in monthly antidiabetic drug costs between the 2 groups. CONCLUSIONS: There are currently no studies to our knowledge that evaluate the outcomes of a pharmacist-managed deprescribing program targeting antidiabetic medications. The results of our study showed that deprescribing of selected antidiabetics reduced the risk of hypoglycemia and may have mortality benefit in elderly patients with well-controlled type 2 diabetes, who are taking medications that can cause hypoglycemia. Further and longer studies are needed to validate these benefits. DISCLOSURES: No outside funding was provided to support this research study. The authors of this study have no actual or potential conflicts of interest to report. Parts of this study were presented in a nonreviewed resident poster at the Academy of Managed Care Pharmacy Managed Care and Specialty Pharmacy Annual Meeting; April 23-26, 2018; Boston, MA.