Table 9.

Studies evaluating alfentanil in cats

Type of study	Dose and route*	Assessment	Results	Reference
Experimental	ALF 100 µg/kg	PK	Volume of the central compartment was 0.10 ± 0.01 (0.07–0.14) l/kg (mean ± SEM [range]); volume of distribution at steady state was 0.89 ± 0.16 (0.68–1.83) l/kg (mean ± SEM [range]); clearance was 11.6 ± 2.6 (9.2–15.8) ml/min/kg (harmonic mean ± pseudo-SD [range]); and terminal half-life was 144 (118–501) mins (median [range])	135
Clinical: OHE	PPF + ALF 10 µg/kg, 0.8 µg/kg/min IV, PPF + REMI 2.5 µg/kg, 0.2 µg/kg/min IV; PPF 0.3 mg/kg/h IV	Monitoring of cardiovascular parameters	In both groups, RT, RR, ETCO2 and SpO2 values were not significantly different when compared with baseline, with the exception that RT was lower at skin closure compared with baseline. In the ALF group, but not in the REMI group, HR was higher at some time points during the surgical procedure when compared with baseline. During ligation of the ovary, SAP was higher in the ALF group; from ligation of the ovary to skin closure, SAP was higher in both groups when compared with baseline. There were no significant differences between groups for RR, ETCO2, HR and SpO2. From coeliotomy until ligation of the ovaries, SAP was lower in ALF compared with the REMI group. Overall, the infusion rates of REMI and ALF were 0.24 ± 0.05 mg/kg/min and 0.97 ± 0.22 mg/kg/min, respectively	136
Experimental	PPF + SAL, PPF + SUF, PPF + FEN, PPF + ALF; PPF 7 mg/kg + 0.2 mg/kg/min IV, SUF 0.01 µg/kg/min IV, FEN 0.1 µg/kg/min IV, ALF 0.5 µg/kg/min IV	Interdigital skin clamp to detect MIR	In comparison with baseline values, the ALF group showed a decrease in HR from 30–90 mins of infusion; the decrease in HR was significantly greater 30 mins after anaesthetic induction in the ALF group than in other groups. In the ALF group diastolic blood pressure and mean blood pressure were significantly lower than baseline values from 30–90 and from 15–90 mins after induction, respectively. RR decreased from baseline from 30–90 mins of infusion; ETCO2 increased from 15–90 mins of infusion	41
Experimental	ALF administered IV in order to achieve estimated plasma concentration of 500 ng/ml	MAC determination	ALF reduced isoflurane MAC and caused a significant increase in body temperature, heart rate, mean arterial pressure, mean pulmonary arterial pressure, stroke index, cardiac index, haemoglobin, oxygen delivery index, dopamine, epinephrine, norepinephrine and cortisol values, and a significant decrease in arterial and venous pH	28
Experimental	ALF administered IV in order to achieve plasma concentrations of 50, 100, 250, 500, 750 and 1000 ng/ml		Isoflurane MAC reduction was estimated to be maximal (35.0 ± 6.6%) at a plasma ALF concentration of 500 ng/ml	20
Experimental	ALF 50 μg/kg IV	Tail clamp test	Harmonic mean for the half-life of the rapid distribution was 4.12 mins; slow distribution was 18.8 mins; and elimination phase was 119.2 mins. Analgesia lasted for 21.7 ± 14 mins. ALF caused a transient increase in blood pressure, and respiratory and metabolic acidosis	137

^*See footnote to Table 1

ALF = alfentanil; ETCO₂ = end-tidal carbon dioxide; FEN = fentanyl; HR = heart rate; MAC = minimum alveolar concentration; MIR = minimum infusion rate; OHE = ovariohysterectomy; PK = pharmacokinetics; PPF = propofol; REMI = remifentanil; RR = respiratory rate; RT = rectal temperature; SAP = systolic arterial pressure; SAL = saline; SpO₂ = oxygen saturation of haemoglobin; SUF = sufentanil