Pharmacology II Exam 2 Review Flashcards

100 question and answer flashcards covering Opioid Analgesics, Sedatives & Tranquilizers, Local Anesthetics, Euthanizing Agents, Anticonvulsants, and Behavioral Drugs based on lecture notes.

What are natural alkaloids like morphine and codeine derived from the poppy plant called?

Opiates

What term refers to all synthetic and natural agents that act on opioid receptors?

Opioids

What are the primary clinical uses of opioid analgesics?

Analgesia, sedation, chemical restraint, antitussive, and antidiarrheal

Through which receptor is the primary dose-limiting toxicity of respiratory depression mediated?

$\mu$ (Mu) receptor

What are the effects of binding to the $\mu$ (Mu) receptor?

Excellent analgesia, respiratory depression, decreased GI motility, euphoria or dysphoria, and species-specific sedation or excitement

What are the effects of binding to the $\kappa$ (Kappa) receptor?

Moderate analgesia, sedation, decreased GI motility, and diuresis

What is the clinical significance of the $\delta$ (Delta) receptor in veterinary medicine?

Limited clinical significance, but it modulates $\mu$ and $\kappa$ activity and tolerance development

Which drugs are classified as Schedule II full $\mu$ agonists?

Morphine, Hydromorphone, Methadone, Fentanyl, and Hydrocodone

Which ultra-potent Schedule II opioids are used for wildlife and reversed by Naltrexone?

Etorphine ($M\text{-}99$) and Carfentanil

What is the control schedule and receptor activity of Buprenorphine?

Schedule III; $\mu$ partial agonist and $\kappa$ antagonist

What is the control schedule and receptor activity of Butorphanol?

Schedule IV; $\kappa$ agonist and $\mu$ partial antagonist

Which antidiarrheal agent is a Schedule V opioid?

Lomotil

What is the duration of action for Morphine?

$$1\text{--}4\text{ h}$$

What adverse effect can occur with IV administration of Morphine due to histamine release?

Hypotension

What are the species-dependent CNS effects of Morphine?

Dogs sedate well; cats and horses experience excitation

How does the potency of Hydromorphone compare to Morphine?

$\text{Approximately } 7 \times$ more potent

Why is Hydromorphone preferred in cats?

It requires limited glucuronidation

How does the potency of Fentanyl compare to Morphine?

$\text{Approximately } 100 \times$ more potent

What is the duration of a Fentanyl patch in dogs versus cats?

$3\text{ days}$ in dogs; $5\text{ days}$ in cats

Which opioid has NMDA antagonist activity, making it ideal for neuropathic and orthopedic pain?

Methadone

How does the potency of Hydrocodone compare to Morphine?

$\text{Approximately } 6 \times$ more potent

What is the primary clinical use of Hydrocodone?

Antitussive

How does the potency of Buprenorphine compare to Morphine?

$25 \times$ more potent

What is the duration of action for Buprenorphine?

$4\text{--}8\text{ h}$ (longest DOA of any opioid)

What form of Buprenorphine is administered q24h SQ to cats?

Simbadol

How does the potency of Butorphanol compare to Morphine?

$5\text{--}7 \times$ more potent

What is the duration of action for Butorphanol in horses?

$$30\text{--}90\text{ min}$$

Which non-controlled drug is a $\kappa$ agonist and $\mu$ antagonist used for mild-moderate pain?

Nalbuphine

What is the primary $\mu$, $\kappa$, $\delta$ antagonist used for opioid reversal?

Naloxone (Narcan)

Why is renarcinization typically required when using Naloxone?

Naloxone has a shorter duration of action than most agonists

What are the three mechanisms of action of Tramadol?

Weak $\mu$ agonist (active metabolite), serotonin reuptake inhibitor, and noradrenergic reuptake inhibitor

What is a major risk of combining Tramadol with SSRIs or SNRIs?

Serotonin syndrome

What is the most common opioid given via the epidural route, lasting up to $24\text{ h}$?

Morphine

How do opioids affect body temperature in dogs versus cats/horses?

Dogs pant (lower set point); cats/horses experience hyperthermia (higher set point)

How do opioids affect GI motility?

Initial defecation followed by decreased motility leading to constipation or ileus risk

Are there any FDA approved opioids for food animals?

No

What is the MOA of Phenothiazines like Acepromazine?

Dopamine ($D_2$) antagonist in the CNS

Does Acepromazine provide analgesia?

No

What cardiovascular side effect is caused by the $\alpha_1$ blockade of Acepromazine?

Vasodilation leading to hypotension

Why should Acepromazine be avoided in stallions?

Risk of paraphimosis

How does Acepromazine affect red blood cell count?

Decreases PCV via splenic sequestration

What is the MOA of Azaperone?

$D_2$ (also $D_1$, $5\text{-HT}$, $\alpha \text{-}1$, and histamine) receptor antagonist

What are the components of the 'BAM' protocol in wildlife?

Butorphanol, Azaperone, and Medetomidine

What is the MOA of Alpha-2 Agonists?

Presynaptic $\alpha_2$ receptor stimulation in the dorsal horn of the spinal cord, decreasing norepinephrine release

Rank the specific $\alpha_2$ agonists from most to least selective/potent.

Dexmedetomidine > Detomidine > Xylazine

What are the cardiovascular effects of Alpha-2 Agonists?

Decreased HR (reflex bradycardia) and CO; initial hypertension followed by hypotension

What is the effect of $\alpha_2$ agonists on blood glucose?

Hyperglycemia due to decreased insulin release

Why are ruminants highly sensitive to Alpha-2 agonists?

They have a higher percentage of $\alpha_{2D}$ receptor subtypes

Which Alpha-2 agonist is the small animal gold standard?

Dexmedetomidine (Dexdomitor)

Which Alpha-2 agonist is FDA approved in horses and causes significant ataxia?

Detomidine (Dormosedan)

What is the specific reversal agent for Dexmedetomidine?

Atipamezole (Antisedan)

What is the preferred reversal for Xylazine in ruminants?

Tolazoline

What are the target agonists for Yohimbine reversal?

Xylazine and Detomidine

What is the MOA of Benzodiazepines?

Potentiate $GABA\text{-}A$ receptor activity causing hyperpolarization

Do Benzodiazepines provide analgesia?

No

Which Benzodiazepine precipitates when mixed with other drugs due to its propylene glycol base?

Diazepam

Which water-soluble Benzodiazepine is preferred for smoother induction in small animals?

Midazolam

What is the components of Telazol?

Tiletamine and Zolazepam

What is the reversal agent for Benzodiazepines?

Flumazenil

What is the MOA of Guaifenesin?

Central-acting skeletal muscle relaxant

What are the three components of the 'Triple Dip' (GKX) for TIVA?

Guaifenesin, Ketamine, and Xylazine

What is the withdrawal period for Guaifenesin in food animals (meat and milk)?

$3\text{ days}$ for meat; $48\text{ hours}$ for milk

What is the MOA of Local Anesthetics?

Block voltage-gated $Na^+$ channels to prevent depolarization and action potential propagation

In what order are sensations lost during local anesthesia (differential blockade)?

Pain, then temperature, then touch, then pressure, then motor function

What chemical property of local anesthetics determines their onset of action?

$pKa$ (Closer to physiologic pH means faster onset)

Which class of local anesthetics includes Procaine and Tetracaine and has an increased allergy risk?

Esters

Which class of local anesthetics includes Lidocaine and Bupivacaine and undergoes hepatic metabolism?

Amides

What is the onset and duration of action for Lidocaine?

Onset: $1\text{--}2\text{ min}$; Duration: $1\text{--}2\text{ h}$

Which local anesthetic is also used as a Class IB anti-arrhythmic?

Lidocaine

What is the onset and duration of action for Bupivacaine?

Onset: $5\text{--}10\text{ min}$; Duration: $4\text{--}8\text{ h}$

What is the primary danger of administering Bupivacaine intravenously?

Cardiotoxicity (ventricular arrhythmias)

Which local anesthetic is similar to Lidocaine but produces less tissue irritation in horses?

Mepivacaine

Which local anesthetics are used for ophthalmic purposes?

Proparacaine and Tetracaine

What is the treatment for severe systemic toxicity (CNS/CV) from local anesthetics?

Supportive care and Intralipid therapy

Why is Epinephrine ($1:200,000$) added to local anesthetics?

Vasoconstriction decreases absorption and increases the duration of action

Why is Bicarbonate added to local anesthetic formulations?

It increases the percentage of non-ionized drug for faster onset (especially with Lidocaine)

What is the MOA of Pentobarbital sodium for euthanasia?

Potentiates $GABA\text{-}A$ activity leading to hyperpolarization and CNS shutdown

What are the primary target events in euthanasia following CNS depression?

Respiratory arrest followed by cardiac arrest

Which electrolyte is used to cause asystole only after deep anesthesia or unconsciousness?

Potassium Chloride (KCl)

What agent is acceptable for euthanasia in fish and amphibians?

MS-222 (Tricaine Methanesulfonate)

How is death confirmed after euthanasia?

Absence of heartbeat and respiration for more than $2\text{ min}$ with fixed dilated pupils

What are the common general targets for anticonvulsant drugs?

Increase $GABA$ activity, decrease $Na^+$ or $Ca^{2+}$ channel activity, and decrease glutamate release

Which drugs are used for acute seizure control or status epilepticus?

Diazepam and Midazolam

What is the drug of first choice for chronic seizure control in dogs and cats?

Phenobarbital

How long does it take Phenobarbital to reach steady-state plasma concentration?

$$2\text{--}3\text{ weeks}$$

What is the half-life of Phenobarbital in dogs versus cats?

Dogs: $2\text{ days}$; cats: $1\text{ day}$

What is the toxic risk to the liver with Phenobarbital use?

Hepatotoxicity and superficial necrolytic dermatitis (hepatocutaneous disease)

How many milligrams are in one grain of Phenobarbital?

$$65\text{ mg}$$

What is the MOA of Potassium Bromide (KBr)?

Hyperpolarizes neurons via chloride ($Cl^-$) channel competition

How is Potassium Bromide eliminated, and why is this useful?

Renal elimination; it is safe for pets with liver disease

Why is Potassium Bromide avoided in cats?

It can cause feline respiratory signs resembling asthma

What is the MOA of Levetiracetam (Keppra)?

Binds $SV2A$ (synaptic vesicle protein) to decrease neurotransmitter release

Why is Levetiracetam the drug of choice for hepatic or refractory epileptics?

It has minimal hepatic metabolism and rapid onset

What is the MOA of Zonisamide?

Blocks $Na^+$ and T-type $Ca^{2+}$ channels to decrease repetitive firing

What is a specific contraindication for Zonisamide?

Sulfonamide hypersensitivity (it is sulfa-based)

What is the MOA of SSRIs like Fluoxetine?

Selective serotonin ($5\text{-HT}$) reuptake inhibition

What are the clinical uses for Fluoxetine?

Separation anxiety, urine spraying, aggression, and compulsive behaviors

What is the MOA of TCAs like Clomipramine and Amitriptyline?

Block norepinephrine ($NE$) and serotonin ($5\text{-HT}$) reuptake; also provide anticholinergic and antihistamine effects

Which TCA is used for canine OCD and separation anxiety?

Clomipramine

Which TCA is used for urine-marking and feline interstitial cystitis?

Amitriptyline