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.