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  • Author or Editor: R. M. Bednarski x
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The effects of propofol on anesthetic induction were evaluated in 40 dogs anesthetized with isoflurane. Propofol is a rapidly acting, nonbarbiturate drug that induces anesthesia of ultrashort duration with iv administration. Four preanesthetic regimens were used: anesthesia without preanesthetic drugs; or with preanesthetic administration of acepromazine (0.1 mg/kg of body weight, im), diazepam (0.2 mg/kg, iv), or acepromazine (0.02 mg/kg) and butorphanol (0.4 mg/kg) im. Heart rate, systolic arterial blood pressure (sap), respiration, quality of induction and recovery, and adverse effects were recorded. Intravenous propofol administration induced a variable period of apnea in 34 of 40 dogs. Cyanosis (in 2 dogs) and signs of pain on injection (in 3 dogs) were infrequently observed during induction. One dog developed ventricular premature depolarizations after propofol administration. Venous CO2 tension increased and pH decreased immediately after propofol administration, regardless of preanesthetic regimen. The sap significantly (P < 0.05) decreased after propofol administration in dogs treated with acepromazine (sap, 178 mm of Hg before vs 128 mm of Hg after propofol) and with acepromazine/butorphanol (sap, 184 mm of Hg before vs 98 mm of Hg after propofol). When used for induction, propofol induces anesthetic-related adverse effects, some of which can be minimized by preanesthetic medication. Recovery characteristics varied with preanesthetic medication, independent of propofol administration.

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in Journal of the American Veterinary Medical Association


Objective—To determine pharmacokinetic and pharmacodynamic properties of midazolam after IV and IM administration in alpacas.

Animals—6 healthy alpacas.

Procedures—Midazolam (0.5 mg/kg) was administered IV or IM in a randomized crossover design. Twelve hours prior to administration, catheters were placed in 1 (IM trial) or both (IV trial) jugular veins for drug administration and blood sample collection for determination of serum midazolam concentrations. Blood samples were obtained at intervals up to 24 hours after IM and IV administration. Midazolam concentrations were determined by use of tandem liquid chromatography–mass spectrometry.

Results—Maximum concentrations after IV administration (median, 1,394 ng/mL [range, 1,150 to 1,503 ng/mL]) and IM administration (411 ng/mL [217 to 675 ng/mL]) were measured at 3 minutes and at 5 to 30 minutes, respectively. Distribution half-life was 18.7 minutes (13 to 47 minutes) after IV administration and 41 minutes (30 to 80 minutes) after IM administration. Elimination half-life was 98 minutes (67 to 373 minutes) and 234 minutes (103 to 320 minutes) after IV and IM administration, respectively. Total clearance after IV administration was 11.3 mL/min/kg (6.7 to 13.9 mL/min/kg), and steady-state volume of distribution was 525 mL/kg (446 to 798 mL/kg). Bioavailability of midazolam after IM administration was 92%. Peak onset of sedation occurred at 0.4 minutes (IV) and 15 minutes (IM). Sedation was significantly greater after IV administration.

Conclusions and Clinical Relevance—Midazolam was well absorbed after IM administration, had a short duration of action, and induced moderate levels of sedation in alpacas.

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in American Journal of Veterinary Research