Premedication

Use of premedication can decrease patient stress and anxiety, improve the ease of patient handling, improve muscle relaxation and decrease the requirements for the most potent anaesthetic drugs. As a result, a smoother anaesthetic induction, transition and recovery can be achieved.

Premedications

A range of medications are commonly used in the premedication period including;

  • Phenothiazines (acepromazine)
  • Benzodiazepines (diazepam, midazolam)
  • Alpha-2-adrenoreceptor agonists (medetomidine, dexmedetomidine)
  • Opioids (methadone, buprenorphine, morphine, butorphanol)
  • NSAIDS (carprofen, meloxicam)
  • (Anticholinergic agents (atropine))

Premedication effects on the anaesthesia

Successful premedication smooths the stages of anaesthesia – induction, transition, maintenance and recovery. The pre-anaesthetic period requires focus and the careful selection of the most appropriate premedication tailored to the individual patient.

Reducing stress for the patient (and clinic personnel) during the pre-anaesthetic period is essential. This may be achieved with a combination of a quiet, calm environment, considerate patient handling and the use of suitably selected sedatives and analgesics.

Some premedicants have greater or lesser effect on the anaesthetic. For example, alpha-2 agonists (medetomidine, dexmedetomidine) may decrease the required dose of Alfaxan and increase the circulation time. As a result it may be necessary to administer Alfaxan more slowly and a lower dose than calculated may be required to induce anaesthesia.

Analgesia is an important aspect of premedication. Selection of the most suitable analgesic should take into consideration the species and breed of animal, the type of procedure and degree of pain expected, the level of analgesia provided by the drug and the length of the expected analgesic effect from the drug.

Selecting the most appropriate route of administration is necessary to ensure maximum response to the premedicant. The intramuscular and intravenous routes, where licensed for the specific drug, are the ideal. As a component of best practice, Jurox encourages veterinarians to make placement of an intravenous catheter prior to anaesthetic induction a standard practice.

Allowing sufficient time for premedicants to take effect is essential for ensuring smooth anaesthetic induction.

Alfaxan® has been shown to be safe when used with a wide range of premedicant drugs. 26-35, 38, 39, 42-44, 53, 54

Veterinary surgeons should assess each patient’s individual requirements and tailor the selection of premedicant drugs to that specific animal thus avoiding ‘blanket’ premed regimes.

Premedication Agents

Veterinary surgeons have access to a wide range of premedicant drugs.
Alfaxan has safely been used with a wide range of premedicant drugs. 26-35, 38, 39, 42-44, 53, 54

DrugTime to peak sedaction or effectDuration of actionReversible?Analgesia?
*Note that the duration of action of many of these drugs will vary between species, the route and dose administered, the health status of the patient and any concurrent medication.  The times given are approximate guidelines only.
Reproduced with permission from the BSAVA Manual of Canine and Feline Anaesthesia and Analgesia, 3rd edition, © BSAVA
Acepromazine35-40 minutes i.m.
15-20 minutes i.v.
4-6 hoursNoNo
Medetomidine
Dexmedetomidine
15-20 minutes i.m.
2-3 minutes i.v.
Sedation: 2-3 hours
Analgesia: 1 hour
Yes – with atipamezoleYes
Midazolam10-15 minutes i.m.
5 minutes i.v.
1-1.5 hoursYes – with flumazenilNo
Diazepam10-15 minutes i.m.
5 minutes i.v.
2 hoursYes – with flumazenilNo
Atropine20-30 minutes i.m.
1-2 minutes i.v.
Vagal inhibition: 60-90 minutesNoNo
Glycopyrronium20-30 minutes i.m.
2-3 minutes i.v.
Vagal inhibition: 2-3 hoursNoNo
Methadone20-30 minutes i.m.
2-5 minutes i.v.
2-4 hoursYes – with naloxoneYes
Morphine20-30 minutes i.m.
Not recommended i.v.
2-4 hoursYes – with naloxoneYes
Pethidine20-30 minutes i.m.
Contraindicated i.v.
1-1.5 hoursYes – with naloxoneYes
Buprenorphine30-45 minutes i.m.
12-15 minutes i.v.
6 hoursYes – with naloxoneYes
Butorphanol20-30 minutes i.m.
2-5 minutes i.v.
1-1.5 hoursYes – with naloxoneYes