Effect Of Pentazocine on Chlorpromazine Sedation in Dogs

Abstract

The sedative effects of intramuscular administration of chlorpromazine (4mg/kg) (CHL) and chlorpromazine-pentazocine (4 and 2 mg/kg) (CHL-PEN) and their effects on selected cardiorespiratory parameters were assessed in five Nigerian indigenous dogs comprising 3 males
and 2 females (weight 13.5 ± 3.7 kg; Means +/- SD). Dogs were subjected to both treatments at an interval of one week using simple randomized cross-over design. Sedation was scored with a simple descriptive scale (range 0-3) and cardiorespiratory parameters (heart and respiratory rates, temperature, systolic-, diastolic-, and mean arterial pressures) were obtained before drug administration and subsequently at 15-minute intervals over a period of 120 minutes with a multiparameter patient monitor. Data were analysed with student-t test and Analysis of Variance at α levels p ≤ 0.05.

Onset of drug effect was 21.4 ± 6.7 (CHL) and 17.6 ± 2.3 minutes (CHL-PEN) (p > 0.05). Time to sleep was significantly longer (p = 0.04) with CHL (36.6±12.9 minutes) than with CHL- PEN (21.4±6.0 minutes). Peak sedation occurred at 60 minutes with all dogs in the CHL group
moderately sedated while all dogs in the CHL-PEN group were deeply sedated. With CHL-PEN, there was mild analgesia of 86±18.8 minutes while there was none with CHL. Measured cardiorespiratory parameters fell insignificantly from baseline values with both treatments but were within reference ranges.

In conclusion, pentazocine addition to chlorpromazine enhanced the sedative potential of chlorpromazine, produced mild analgesia with minimal effect on cardiorespiratory function, and will be a useful phenothiazine sedative-opioid combination for sedation in canine practice in Nigeria.