Barbiturate Pharmacology Quiz

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Questions and Answers

Which barbiturate is commonly used for long-term seizure management?

Phenobarbital (correct)

Primidone

Pentobarbital

Thiopental

What is the primary mechanism of action of Primidone?

Prevents analgesia

Enhances neurotransmitter release

Acts as a potent sedative

Increases seizure threshold (correct)

At what dose does pentobarbital primarily exhibit general anesthesia?

High Dose

Moderate Dose (correct)

Ultra Low Dose

Low Dose

Which characteristic is true for high doses of barbiturates?

Provides poor analgesia Signup and view all the answers

Which drug is noted for having no hypnotic effects?

Primidone Signup and view all the answers

Which barbiturate is most commonly associated with significant cardiopulmonary depression?

Pentobarbital Signup and view all the answers

What is the relative potency of Primidone compared to Phenobarbital?

1/30 Signup and view all the answers

Which barbiturate is primarily used as an antidote to specific overdoses?

Pentobarbital Signup and view all the answers

Which opioid is indicated for its use in IV anesthesia in swine?

Oxymorphone Signup and view all the answers

What is the primary reason for using Methadone over Morphine?

Less sedation and vomiting Signup and view all the answers

Which opioid has the highest potency according to the order of potency mentioned?

Carfentanil Signup and view all the answers

Which opioid has a rapid onset of action but a shorter duration compared to Morphine?

Fentanyl Signup and view all the answers

What characteristic differentiates Hydromorphone from Oxymorphone?

Lower analgesic potency Signup and view all the answers

For which purpose is Fentanyl primarily used in veterinary medicine?

For chronic pain management Signup and view all the answers

Which of the following opioids is known for having 10 times more analgesic potency than Morphine?

Oxymorphone Signup and view all the answers

Which opioid derivative has the least potency in comparison to others listed?

Alfentanil Signup and view all the answers

What is a unique characteristic of fluphenazine?

Used in the treatment of schizophrenia. Signup and view all the answers

What is a contraindication for azaperone?

Should not be given intravenously in horses. Signup and view all the answers

What comparison is made regarding droperidol's potency?

1000 times more potent anti-emetic than chlorpromazine. Signup and view all the answers

Which drug was used as a performance-enhancing substance in racehorses but is now banned?

Fluphenazine. Signup and view all the answers

What is the role of droperidol when combined with fentanyl?

To produce neuroleptanalgesia. Signup and view all the answers

What should be done to pigs after receiving azaperone to avoid excitement?

Leave them undisturbed for 20 minutes. Signup and view all the answers

Which phenothiazine is known for its approval across multiple animal species?

Promazine. Signup and view all the answers

What is a common characteristic of butyrophenones as explained in the document?

They share a similar mechanism of action with phenothiazines. Signup and view all the answers

Study Notes

Drugs Acting on the Nervous System

Drugs acting on the nervous system are categorized to aid in understanding and treatment.
An unauthorized reproduction and/or distribution of this document is punishable by law.

Divisions of the Nervous System

Central Nervous System (CNS): Contains the brain and spinal cord;integrates control center.
Peripheral Nervous System (PNS): Consists of peripheral nerves, cranial, and spinal nerves; communication between the CNS and body.
- Sensory (Afferent) Division: Composed of sensory neurons; conducts signals from receptors to the CNS.
- Motor (Efferent) Division: Contains motor neurons; conducts signals from the CNS to effectors (muscles and glands).
  - Autonomic Nervous System: Controls involuntary responses.
    - Sympathetic Division: Mobilizes body systems (flight-or-fight).
    - Parasympathetic Division: Conserves energy (rest-and-digest)
  - Somatic Nervous System: Controls voluntary movement.

CNS Drugs

Organs: Brain and spinal cord
Goals: Develop drugs to elucidate and manipulate the normal CNS, to correct pathophysiological changes in abnormal CNS.
Functions:
- Anticonvulsive effects
- Tranquilization
- Analgesia
- Anesthesia

CNS Drug Classifications

Narcotics
Hypnotics
Tranquilizers
Anesthetics
Neuroleptics
Analgesics
CNS Stimulants
Sedatives
Dissociatives
Anticovulsants

Seizures vs. Convulsions

Seizures: A sudden, uncontrolled electrical disturbance in the brain.
Convulsions: Specific type of seizure characterized by involuntary muscle contractions. All convulsions are seizures but not all seizures are convulsions.

Anticonvulsants MOA

Mechanism of Action (MOA): Stabilization of neuronal membranes
- 1. Hyperpolarization of neuronal membranes through ion channels.
  - Blocks sodium channels.
  - Activates potassium channels.
  - Regulates calcium channels.
- 1. Hyperpolarization of neuronal membranes through GABA-gated chloride channels.

Anticonvulsants Indications & Adverse Effects

Indications: Reduce the incidence, severity, or duration of seizures.
Adverse Effects:
- Withdrawal symptoms, seizures, status epilepticus can follow rapid cessation or administration with other drugs
- Lowered seizure threshold when administered with other drugs.
  - Phenothiazines (e.g., Acepromazine).
  - Anthelminthics (e.g., Pyrantel, Levamisole).
  - Metoclopramide.
- Enzyme induction (Cytochrome P450)
- Hepatotoxicity

Barbiturates

Classification: Anticonvulsant
Subtypes: Phenobarbital, Primidone, Pentobarbital
Difference in Duration of Action: Ultra-short acting, Short acting, Long acting

Benzodiazepines

Classification: Anticonvulsants
Subtypes: Diazepam, Midazolam, Lorazepam, Zolazepam
Reversal Agent: Flumenazil (competitive antagonist)

Bromides

Classification: Anticonvulsants
Subtype: Potassium bromide (KBr)
MOA: Hyperpolarization of neuronal membranes through chloride channels.
Not to be used in Cats: Because it can cause severe asthma-like symptoms

Adjuncts

Levetiracetam
Zonisamide
Gabapentin
Felbamate
Phenytoin

Phenytoin

MOA: Sodium influx during action potential, Calcium influx during depolarization, delayed potassium efflux during action potential.
Unique Characteristics: Not recommended anti-convulsant due to short half-life, Tx/Mgt for digitalis-induced ventricular arrhythmias due to its lidocaine-like effects.

Tranquilizers, Ataractics, Neuroleptics, & Sedatives

Description: Drugs that calm the animal and promote sleep but do not necessarily induce sleep. Often used as pre-anesthetic medications.

Phenothiazines

Description: Tranquilizers that block dopamine, α-1, histamine, acetylcholine & serotonergic receptors, leading to a calming effect.
Pharmacological Effects: Tranquilization, hypotension, and epinephrine reversal.
Adverse Effects: Respiratory depression, hyperprolactinemia, hyperglycemia, decreased GIT motility, and impaired thermoregulation.
Extrapyramidal Symptoms: Can cause muscle tremors, rigidity, bradykinesia, dystonia, and dyskinesia.
Indications: Tranquilization, anti-emetic, pre-anesthetic.
Contraindications: Epilepsy, hypovolemic/hypotensive patients, liver dysfunction, anti-ChE, poisoning.
No Reversal Agent Available
Specific Phenothiazines: Acepromazine, Chlorpromazine, Promazine, Fluphenazine.

Butyrophenone

Description: Tranquilizers that are more potent than phenothiazines. Block dopamine receptors.
Pharmacological Effects: Same as phenothiazines, potentially more potent.
Specific Butyrophenones: Droperidol, Azaperone (often used with fentanyl or other anesthetics in animals).

α-adrenergic Agonists

MOA: Activate α-2 receptors and α-1 receptors (high doses), decreasing neurotransmitter release.
Pharmacological Effects: Sedation, analgesia, muscle relaxation, emesis, mild hypertension to hypotension, diuresis, and hypoxemia (in ruminants).
Specific α-agonists: Xylazine, Detomidine, Medetomidine, Romifidine.
Important Characteristics & Considerations for use:
- Xylazine, for example, has a prolonged effect and can be used pre-anesthetically.

Chloral Hydrate

MOA: Reduced to trichloroethanol in the body; causes CNS depression and sedation.
Pharmacological Effects: Marked hypnotic effect, and cerebral/respiratory depression as well as poor analgesic capability.
Indications: Primarily in horses, basal necrosis, and anesthesia.

Opioids

Description: Drugs that bind to opioid receptors.
Subtypes: Agonists, antagonists, and partial agonists.
Opiates: Derived from opium (poppy plant). These are typically opioid agonists.
Examples of Opioids: Morphine, Tramadol, Methadone, Oxymorphone, Hydromorphone, Fentanyl, Alfentanil, Sufentanil, Carfentanil, Buprenorphine, Nalbuphine, Naloxone, Naltrexone, and Butorphanol.
Important Considerations: Potency, duration of action, receptor affinity, safety margin.

Anxiolytics/Anti-depressants

Anxiolytics: Drugs designed to treat anxiety;
Anti-depressants: Used for depression, anxiety or other mood disorders.
- Tricyclic Antidepressants (TCAs): Amitriptyline, Clomipramine, Imipramine, Doxepin
- Serotonin Selective Reuptake Inhibitors (SSRIs): Fluoxetine, Paroxetine, Sertraline, Fluvoxamine
- Monoamine Oxidase Inhibitors (MAOIs): Selegiline
- Progestins: Medroxyprogesterone acetate (MPA), Megestrol acetate (MA). Most often progestins are used to treat more complex behavioral or medical conditions.

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Description

Test your knowledge on barbiturates, their mechanisms of action, and their clinical uses. This quiz covers aspects including seizure management, anesthesia dosage, and overdoses. Enhance your understanding of the pharmacological characteristics and effects of various barbiturates.