Common Anesthetic Drugs and Their Properties Flashcards
premedication
What are some indications and contraindications of anticholinergics? What are the most commonly used anticholinergics in small animal clinical practice?
increase heart rate, decrease bronchial and oral secretions, cause bronchodilation, cyclopegia, mydriasis and increases stomach pH.
should not be used with alpha 2 agonists
exception is when alpha 2 agonists are combined with acepromazine and an opioid for IM premedication.
atropine and glycopyrrolate
have dose dependent cholinergic effects: bradycardia and bradyarrythmias when low doses are administered.
premedication
What are the indications and contraindications for phenothiazines? What is the most common phenothiazine used in clincial small animal practice?
acepromazine
antagozines dopamine actions
reduces aggressive behaviors due to dominance (maybe not fear)
anti-emetic, anti-spasmodic, weal anti-histamine effects
used for standing sedation in horses
may exhibit prolonged effects in patients with compromised hepatic function (no antagonist available)
no analgesia
lowers seizure hreshold but also has been known to cause seizures with portocaval shunt
HYPOTENSION caused by VASODILATION: discouraged in hypotensive/hypovolemic patients
protective against catecholamine-induced dysrhythmias
premedication
What are the indications and contraindications for alpha 2 agonists? What are the common drugs used? Reversals?
excellent analgesic, hypnotic sedative
reversal agents available
each drug hs both alpha 1 and 2 effects:
xylazine, detomidine, romifidine, medetomidine, dexmedetomidine.
dexmedetomidine is used for standing sedation in horsesonyl use in healthy and young animals
significant effects on cardiovascular system: increase in peripheral resistance and decrease in heart rate, decrease in CO, second degree AV block and other bradyrhythmias.
clinical observations: cyanosis and pale MM.
concurrent use of anticholinergic not remmended as it increase myocardial work without increasing CO.
If combined with acepromazine, then add anticholinergic, anticholinergic may not be so bad.
REVERSAL: yohimbine, tolazoline, atipamezole
acepromazine and dexmedetomidine combination is favored by some faculty
premedication
What are some indications and contraindications of benzodiazepines? What are the most commonly used benzos in small animal clinical practice?
Diazepam, Midazolam, Zolazepam (in Telazol)
Midazolam: rapid and non-painful upon injection, advantage to SC and IM
Diazepam: pain on injection and unreliably absorbed through IM
benzos minimize excitement in horses following sedation when used duirng induction
For the very old, young, and sick
REVERSAL: Flumazenil
insignificant cardiovascular effects but arrhythmias and hypotension with rapid IV administration (not in Midazolam and has been safe in cardiac patients)
not an analgesic
treats seizures in all patients
premedication
What are some indications and contraindications of opioids? What are the most commonly used opioids in small animal clinical practice?
Morphine, sedative and longer duration of action, SC does not cause signifcant histamine release
Hydromorphone
Methadone, doesn’t cause vomitting, effective sedative when given IM (not SC)
Meperidine (histamione release) and fentanyl (cardio safety) short actng opioids
Buprenorphine
Butorphanol
bradycardia with opioid use can be mitigated with anticholinergics. respiratory depression is mild.
What are some indications and contraindications for propofol?
no analgesia
induction for anesthesia
Horses get excited on propofol alone but is now commonly being used in combination with ketamine
Viable choice for patients with intra-cranial pressure changes
short duration and clearance: suitable for patients with severe hepatic disease (not cardio!)
Cat: glucoronidtion thing, accumulation, and heinz body anemia
arterial hypotension, negative inotriopic effects (reduced by slower administration)
Premedication and benzoz reduce the dose requirement
What are some indications and contraindications for Alflaxalone?
no anlgesia
inducition agent
Sedation in patients that are hard to handle
hypotension, use in mild to moderate but not severely compromised cardio patients.
What are some indications and contraindications for etomidate?
sedative, induction
pain on injection, needs to be diluted
good for HCM cat and head trauma patients (minimal cardiopulmonary effects, mild decrease in HR, transient decrease in respiratory.
What are some indications and contraindications for ketamine?
cats more susceptible to prolonged effects upon repeated doses.
Given with Benzos to improve muscle relaxation (and guafenesin)
Given with propofol in horses to minimize hypertoxicity seen with ketamine
increases sympathetic tone, which increases HR, myocardial contractility and blood pressure.
AVOID in restrictive or hypertrophic cardiac disease patients (myocardial contractility may be depressed following drug administration in patients with depleted sympathetic nerve)
tiletamine similar to ketamine, usually found in Telazol
What are some indications and contraindications for opioids?
safe in compromised patients
Fentanyl, methadone, and hydromorphone do not release histamine
fentanyl most common opioid for anesthesia induction (hydromorphone and methadone can be similarly used)
