Drugs for anesthesia

Sedatives & Tranquilizers

Benzodiazepines

  • Types:
    • Diazepam
    • Midazolam
    • Zolazepam
  • Mechanism of Action:
    • GABA receptor agonist
  • Effects:
    • Sedation
    • Muscle relaxation
    • Anticonvulsant
    • Note: No analgesia provided.

Phenothiazines

  • Types:
    • Acepromazine
    • Propiopromazine
    • Methotrimeprazine
  • Indications:
    • Mild sedation
    • Reduce opioid-induced emesis
    • Antiarrhythmic
  • Adverse Effects:
    • Hypotension
    • Hypothermia

Alpha-2 Agonists

  • Types:
    • Xylazine
    • Medetomidine
    • Dex-medetomidine
    • Romifidine
  • Reversal Agents:
    • Yohimbine (for xylazine)
    • Antisedan (for others)
  • Effects:
    • Sedation
    • Hypnosis & anesthesia
    • Analgesia
    • Muscle relaxation

Cautions

  • Abortions:
    • Use of anesthetics may increase risk.
  • Cattle Sensitivity:
    • Caution advised due to potential adverse effects.

Anticholinergics

  • Types:
    • Atropine
    • Glycopyrrolate
  • Effects:
    • Inhibit parasympathetic nervous system
    • Increase heart rate (to treat or prevent preanesthetic bradycardia)
    • Reduce airway secretions
    • Decrease gastrointestinal motility
    • Bronchodilation
  • Contraindications:
    • Tachycardia
    • Congestive Heart Failure (CHF)/cardiac disease
    • Glaucoma

Analgesics

Opioids

Mu Receptor
  • Characteristics:
    • Produces strong analgesia and sedation
  • Examples of Pure Agonists:
    • Morphine
    • Hydromorphone
    • Methadone
    • Fentanyl
    • Oxymorphone
    • Heroin
    • Codeine
  • Indications:
    • Treatment of acute pain
    • Sedation
  • Adverse Effects:
    • Respiratory depression
    • Dysphoria
    • Hyperesthesia
    • Gastrointestinal disturbances
Kappa Receptor
  • Characteristics:
    • Provides weak analgesia, mild sedation, or dysphoria
Partial Agonists
  • Characteristics:
    • Partial stimulation of Mu receptor
  • Example:
    • Buprenorphine
  • Indications:
    • Treatment of mild to moderate pain
Mixed Action Agents
  • Example:
    • Butorphanol
  • Characteristics:
    • Agonist at Kappa receptor, antagonist at Mu receptor
  • Caution:
    • Do not mix with Mu opioids.
Pure Antagonists
  • Examples:
    • Naloxone
    • Naltrexone
  • Characteristics:
    • Fully antagonize Mu receptors
    • Used to reverse effects of opioids

Summary of Analgesics

  • Potency Effects vs. Dose Required:
    • Potency refers to the strength of a drug based on the dose required to achieve maximum effect.
  • Efficacy:
    • Compares strength among different drugs.

Anesthesia

Local Anesthesia

  • Use:
    • Used to block sensation in a specific area without affecting consciousness.

Regional Anesthesia

  • Use:
    • Targets larger areas of the body (e.g., epidurals).

Surgical Anesthesia

  • Use:
    • Induced for procedures that require complete unconsciousness and lack of sensation.