Lack of pharmacokinetic interaction between butorphanol nasal spray and cimetidine

ABSTRACT

The potential for a pharmacokinetic interaction between butorphanol nasal spray and cimetidine, under steady state conditions, was evaluated in 16 healthy male volunteers. Subjects received either a 1  mg butorphanol nasal spray every 6  h or a 300  mg cimetidine tablet every 6  h on days 1–4, the combination of two compounds every 6  h on days 5–8 and the original treatment as described in the first segment (days 1–4) on days 9–12. Serial blood and urine samples were collected on days 4, 8 and 12, and additional blood samples were taken immediately, prior to the morning dose on days 3, 7 and 11. Based on the analysis of the C_min samples, the plasma concentrations of cimetidine and butorphanol achieved steady state by the third day of dosing. No statistically significant differences were found in the plasma concentrations of butorphanol or cimetidine (except for t_½ and MRT) between any of the treatment phases. Butorphanol nasal spray and cimetidine can be co-administered without any adjustment of dosage for either drug.