mild sedation in dogs... BUT! excitement/inc locomotor activity in cats and horses
how do opioids affect body temperature?
there can be hyperthermia in cats! (and horses) (hypothermia in dogs)
do opiates cause emesis or anti-emesis?
which opiates can be used as antitussives?
codeine, butorphanol (weak ones--horse with a cough)
how do opiates affect the resp. system?
resp. depression (dose dependent)
how do opiates affect the CV system?
MINIMAL effects on CV system! It will dec HR with high doses though (sympathetic tone dec)
how are histamine and opioids related? (explain what happens)
morphine and meperidine IV cause histamine release, which leads to hypotension and reflex tachycardia
what are the GI effects of opioids? (spp diffs)
(1) Small animals: nausea and vomiting (1) Large animals: decrease in GI motility, (Ileus and colic in horses, ruminal atony in ruminants)
which opioids are MOST LIKELY to cause emesis?
MORPHINE- chemoreceptive trigger zone affected. route of admin plays a role- IV usually worse than IM. HYDROMORPHONE, OXYMORPHONE
what is the theraputic window like for opioids? (sp diffs)
in DOGS there is a LARGE therapeutic window. In HORSES/CATs there is a SMALL therapeutic window
mu receptor, full agonists--> (read the) list (of) these
(basically the ones she cared about) morphine, methadone, meperidine (pethidine), hydromorphone, oxymorphone, fentanil, alfentanil, remifentanil, etorphine, carfentanil
mu receptor full agonists--> what is their affinity? intrinsic activity? does effect depend on dose? what schedule are they?
HIGH affinity and intrinsic activity, they are dose dependent, and they are schedule II drugs
two super awesome reasons we like to use opioids
(1) reduce amount of anesthetic needed to maintain better CV function (2) they provide WIND UP/ CENTRAL SENSITIZATION (remember, they dont percieve pain during anesthesia but they can still nocicept, which remodells pain perception in the CNS which will lead to increased pain perception while awake)
explain why pregnancy/babies and opioid use is tricky
can cross placental barrier and cause resp. depression in newborn if used for C-section. Also can go into milk to cause problems
do opiates cause miosis or mydriasis?
TRICK QUESTION-- miosis, except in cats, thats mydriasis
what should you be careful about when administering morphine via IV?
rapid IV injection can lead to histamine release (hypotension, reflex tachycardia) (morphine and meperidine are the histamine ones.. Marlyn Manson and his evil HISTAMINE band)
how do cats handle morphine in their system?
there is slow elimination and euphoria in cats (they cant glucoronidate so it takes longer) (cats make the worse kinda morphine addicts)
is methadone synthetic or natural? what is the analgesia like that it provides?
synthetic. It's analgesia is similar to morphine, BUT it has the additional analgesic mechanism of NMDA antagonism (good for producing analgesia also) (which is why methheads are still crazy on it :P)
is meperidine(pethidine) natural or synthetic? how long is it effective for? what other effects does it have? how do you administer it?
synthetic, short acting (1hr), with a mild anticholinergic effect. DO NOT GIVE IV--> HISTAMINE RELEASE (remember- more mep and you'll hiss the mean) (not really her first choice, she said) (this will MEP the floor with your shocked out cholinergically depleted body)
is fentanyl natural or synthetic? how strong is it? how long is it effective for? what are the uses for it?
synthetic. VERY potent, also fast and short acting (20min!!). Can use as CRI, intraoperative bolus, rapid onset sedative IV or IM, "Rapid sequence" induction. Can also use as patches!!
Fentanyl patches--> what are the average doses? who can you use it on? list some pros and cons
12.5-100 micrograms per hour. Avail for dogs, cats, horses, and sheep. CONS: variable time till onset (several hours), variable plasma concentration (unreliable), poor alternative to opioid CRI, potential for abuse. PROS: LONG duration (2-3 days), useful in practice
remifentanil--> what is the potency like? what is onset like? how long is it effective for? how is it metabolized? what is something it's useful for?
potentcy similar to fentanyl (effin strong), with a rapid onset. it is ULTRA SHORT ACTING! 3-4minutes which means you must give CRI. it also has a UNIQUE metabolism by plasma esterases*****NOT BY THE LIVER!!!**** so it is AWESOME for intraoperative use in patients with liver disease. (*BE SURE to administer posteroperative analgesics on time!)
which opioid is awesome for liver patients??
which receptor does buprenorphine work on? what is its affinity and intrinsic activity for it?
PARTIAL Mu agonist with high affinity and low intrinsic activity (high affinity--> slow disassociation from receptor)
what is onset of action like for buprenorphine? what is duration of action like?
SLOW onset of action (20-45min), but LONG duration of action 4-6hr)
longest duration opioid?
buprenorphine (lol longcat is long)
this opioid can be given orally for mucosal absorption in cats
what is the analgesia like for buprenorphine? side effects? what schedule is it?
MODERATE analgesia (it's only a partal mu agonist) so only use for moderate pain, it has minimal side effects (yay! rollie was safe!) and is a schedule III
what receptors does butorphanol work on? what is it's analgesia like? duration? side effect?
mu ANTAGONIST, KAPPA AGONIST. because of this it is only a weak analgesic. The duration is 2-3h. However, this also means minimal side effects
how is butorphanol as a sedative? can it be used for anything else? what schedule is it?
great sedation, good antitussive. It is a schedule IV drug.
what are the complete opioid antagonists? how long do they last?
naloxone and naltrexone. short duration of action.
what is the partial opioid antagonist? why might you wanna use a partial?
butorphanol (mu antagonist, kappa agonist)...useful because if you fully antagonize all the opioid, you also get rid of all the analgesic effects, so they is good for just a teensey weensie OD
what are the most commonly used opioids in horses?
#1 is butorphanol! (registered for use and less side effects). you can also use morphine, meperidine, and methadone (mmm, horse but)
what does neuroleptoanalgesia mean youre giving?
HUMANS: a neurolept (which is a phenothiazine or a butyrophenones along with a opioid). ANIMALS: any sedative+ opioid
what is neuroleptoanalgesia used for in vet med?
preanesthetic med (such as acepromazine+morphine), and for restraint for minor procedures
if adminstered, CANT BE CONTROLLED and are NOT IMMEDIATELY eliminated
dosing--> what do you do for obese patients?
calculate dose for ideal weight!
dosing--> what do you do for patients in shock?
they have reduced CO and centralization of blood, so SLOWLY TITRATE TO EFFECT and reduce dose
the ideal IV anesthetic will have high or low lipid solubility?
HIGH! THE BRAIN IS MADE OF FAT!
do you want active metabolites in a IV anesthetic?
no, or it can build up in system
which barbiturate is ULTRA SHORT ACTING???
Thiopental (theo is not so great in bed, then...)
what is the short acting barbiturate used for euthanasia?
what is the long acting barbiturate used as an anticonvulsant?
big caution with thiopentone/thiopental? what's something you really should do if you inject thiopental?
if extravascular, NASTY TISSUE NECROSIS!!(it is very alkaline) You should ALWAYS flush with saline BEFORE AND AFTER you admin thio.
thiopental comes as a yellow crystalline powder. what should and shouldn't you do in order to make it ready for administration? how good is it after you reconstitute it? how do you know when it isnt good anymore?
reconstitute with sterile water. DO NOT use LRS!!! IT PRECIPITATES OUT OF LRS!! prepared solution stable for approximately 1 week. If solution becomes turbid, it's lost it's efficacy.
what is the plasma protein binding like for thiopental? where is it metabolized? excreted?
65-85% plasma protein bound (considered highly protein bound). it is metabolized in the liver (slow metabolism, even though ultra short acting....) and excreted in the urine
what should you know about repeated injections of thiopental?
after repeated injections, metabolism follows zero-order kinetics, which means there will be a prolonged recovery
what is the MOA for thiopental??
GABA-A agonism. Cl- ion channel--> increasing the duration of the cl- ion channel gate being open! (theo stands in the door holding it open the whole time)
how long will a single dose of thiopental induce general anesthesia?
how does thiopental affect the resp system? CV system?
depresses resp. system, and decreases CO, and causes hypotension. Also causes tachyarrythmias (~VENTRICULAR BIGEMINY!)
which barbiturate can cause ventricular bigemeny, a special kind of tachyarrythmia?
THIOPENTAL (look at slide 20 for an example)
what are some of the CNS effects of thiopental?
species differences with anesthesia induction with thiopental? (any notes about admin in horses?)
can use as anesthesia induction in small animals, in horses can be used as anesthesia induction when in combination with guaifenisen. When using as maintainance in horses, do bolus admin
thiopental--> what percent solution is used in small animals? large animals?
SM: 1.25%-2.5%. LG: 5-10% solution
*how do you administer thiopental?
only use with IV catheter!! CHECK CATHETER BEFORE INJECTION-- TISSUE NECROSIS IF PERIVASCULARLY ADMINISTERED.
If you perivascularly administer thiopental what should you do?
inject the area with saline or lidocaine to dilute it (massage in), try NSAIDS and cooling in the local area affected, possibly parenteral NSAIDs
what is the dose of thiopental in small animals? how do you administer it?
dose is approximately 10mg/kg. you administer a third to a half of the dose, wait for max effect, and then give the rest for effect... FLUSH CATHETER BEFORE AND AFTER INJECTION
why can't you give thiopental to a pt with hepatic dz?
metabolism is in the liver...and the metabolism is slow
why can't you give thiopental to greyhounds?
they have a defect in their metabolic pathways, their low % body fat affects their redistribution, and they have an extremely long recovery because of these things
why can't you give thiopental to a cachexic patient?
no fat to redistribute to--> higher plasma levels--> higher risk of OD
why can't you use thiopental for performing a cesarean section?
mortality in fetus
why can't you use thiopental for anesthesia when you are doing a splenectomy?
barbiturates cause splenic relaxation and congestion, making the procedure more difficult.
6 quick n dirty things you need to know about thiopental
fast acting induction agent, accumulation (slow hepatic metabolism), MUST use IV catheter, respiratory depression, arrythmias (ventricular bigeminy), and avoid in hepatic dz pts/greyhounds
does thiopental provide analgesia?
how is duration of action affected in the body, for thiopental?
thio is redistributed to fat, which limits the duration of action. This means it can also accumulate in fat with repeated admin and lead to prolonged recoveries
(in long notes) how do you treat barbiturate overdose?
artificial ventilation (bc resp depression), maintain body temperature and try not to have the body stagnate in any one position for too long (move every 2hr), inc excretion in urine via alkalinizing urine with bicarb (Carefully) (thio is very alkaline so I'm not sure how this helps, but whatever)