Carbamazepine dose-concentration relationship in elderly nursing home residents.

PURPOSE: To describe the dose-concentration relationships of carbamazepine (CBZ) in elderly nursing home residents and the effect of sex, age, and type of co-medications. RESULTS: This is a cross-sectional study of elderly (> or = 65 years) nursing home residents across the United States (N=92). Data collection was from 1 June 1998 to 31 December 2000. The mean CBZ dose was 9.2+/-5.4 mg/(kg day(-1)) (+/-Standard Deviation) and serum concentration was 5.9+/-2.2mg/L. The daily dose was significantly lower in the oldest-old age group (> or = 85 years, mean 476.9 mg/day (95% confidence interval CI) 326.5-627.3) as compared to the dose in the young-old (65-74 years, mean 724.4 mg/day (CI) 603.4-845.4) (p=0.016). Adjusted for body weight, doses were similar on a mg/(kg day(-1)) basis. The majority of observed CBZ serum concentrations were at the lower end (67.4%) or below (20.7%) the suggested therapeutic range for younger adult outpatients. CONCLUSIONS: Total daily CBZ doses and patient weight decreased with age. The average dose for elderly nursing home residents was approximately 9 mg/(kg day(-1)). Carbamazepine serum concentrations were lower than those used for younger adults, suggesting that these patients may be more sensitive to CBZ.

The validity of epilepsy or seizure documentation in nursing homes.

Recent studies have reported that epilepsy and seizures are common in nursing homes. Prevalence has been reported to range from 5 to 9% and antiepileptic drug (AED) use is even more common. Most of these studies have relied on various forms of nursing home records, but the validity of this source data, while assumed, has not been verified. This study evaluated the degree of agreement between the Minimum Data Set (MDS), both paper and electronic versions, and actual medical records available at the nursing home. Records of 144 residents were evaluated; agreement between paper and electronic versions of the MDS was 97.8%. Agreement between the paper version of the MDS and neurologists review of the nursing home record was 92.3%. However, the criteria for diagnosing epilepsy or seizure were not well documented. Nevertheless, the agreement among nursing home records, paper MDS and electronic MDS is great enough to allow the electronic MDS to be used as a research tool, but more investigation of the actual criteria used by nursing home physicians in diagnosing epilepsy and seizures is necessary.

Valproic acid doses, concentrations, and clearances in elderly nursing home residents.

VPA daily dose and total VPA concentrations for 146 elderly (> or =65 years) nursing home residents collected from June 1998 to December 2000 in homes located throughout the United States are presented. Average age was 78.5+/-8.0 years old. The mean VPA daily dose was 16.2+/-11.2mg/kg and mean total VPA concentration was 48.5+/-24.8 mg/L. The majority (56.2%) of the VPA residents are being maintained at total VPA levels <50mg/L. Mean daily dose (19.4+/-11.4, 16.3+/-12.1, and 11.3+/-7.6 mg/kg/day; p=0.003) and total VPA concentration (56.4+/-25.8, 47.7+/-22.6, and 38.7+/-23.1mg/kg/day; p=0.003) decreased by age groups (65-74, 75-84, and > or =85 years). Daily dose and total VPA concentration were not different in residents receiving inhibitory or inducing co-medications, between men and women, or by albumin level. Total VPA clearance was similar between men and women, among age groups, or according to inducing or inhibiting co-medications.

Phenytoin use in elderly nursing home residents.

BACKGROUND: Phenytoin (PHT) dosing regimens are often determined based on experience in those aged <65 years rather than in those aged >or=65 years. OBJECTIVE: The goal of this study was to determine the impact of sex, age, receipt of concomitant inhibitors or inducers of PHT metabolism, and albumin levels on doses and total serum concentrations of PHT in elderly nursing home residents. METHODS: Consulting pharmacists to nursing homes located throughout the United States collected data from June 1998 to December 2000. The mean daily dose per person and mean total serum PHT concentration were tested for statistical differences by sex, age group (6-74, 75-84, and >or=85 years), coadministration of PHT inhibitors or inducers, and albumin levels. RESULTS: Data were collected from 387 residents (259 women, 128 men) of 112 nursing homes in 19 states who received PHT and for whom PHT concentrations were available. The mean (SD) age of the study population was 79.4 (7.8) years; women constituted 67.0% of the study population. The mean (SD) total daily dose and total PHT concentration were 4.9 (1.8) mg/kg and 11.7 (6.4) mg/L, respectively. In general, women received higher mean (SD) daily doses of PHT compared with men (5.1 [1.8] vs 4.6 [1.6] mg/kg, respectively; P=0.017) to achieve similar total serum concentrations (11.6 [6.4] and 12.0 [6.6] mg/L). PHT doses and serum concentrations were similar between age groups. There were no differences in daily doses (mg/kg or mg/d) or total serum concentrations of PHT based on concomitant use of inhibitors or inducers of PHT metabolism or on albumin levels, CONCLUSIONS: In this study in elderly nursing home residents, women received higher doses of PHT than men to achieve similar total serum PHT concentrations. There were no differences in doses or total serum PHT concentrations by age group, use of concomitant inducers or inhibitors of PHT metabolism, or albumin levels.