Veterinary Drugs: Atropine, Glycopyrrolate, Acepromazine

Drug Study Notes

• Atropine acts as an Ach inhibitor and antimuscarinic, resulting in increased heart rate and blood pressure, while decreasing salivary and bronchial secretions, administered via IV, IM, SQ, or ET tube, with a quick duration of around 60-90 minutes.
• Glycopyrrolate, also an Ach inhibitor and antimuscarinic, has similar effects to atropine, lasting 2-3 hours and administered through IV or IM.
• Acepromazine functions as a dopamine antagonist (phenothiazine) and α-1 adrenergic blocker, causes vasodilation and hypotension, provides tranquilization and antiemetic effects, and lasts for 4-8 hours with no reversal., with its administration occurring intravenously, caution should be exercised in cardiac patients.
• Xylazine, an α-2 agonist, provides sedation, muscle relaxation, and analgesia by reducing norepinephrine and catecholamines, and can lead to bradycardia, hypoventilation, and increased ETCO2 when administered IV, IM, buccally, or epidurally, with a fast onset and a duration of 20-40 minutes.
• Detomidine, another α-2 agonist, induces bradycardia, hypoventilation, and increased ETCO2, but has a longer onset and lasts 90-120 minutes; it is not FDA approved.
• Romifidine is an α-2 agonist with less ataxia than Xylazine, lasts for 45-90 minutes, and provides gastric analgesia by decreasing gastric secretions, but is not FDA approved.
• Medetomidine, an α-2 agonist, causes analgesia for 30 minutes and sedation for 2 hours.
• Dexmedetomidine, an α-2 agonist, is administered IV (1-3 min) or IM (5-10 min) and has the best α-2 selectivity with fewer negative α-1 effects, with a quick onset and a duration of 90-120 minutes.
• Zenalpha, a peripheral α-2 agonist, is a newer option better for cardiac patients for short procedures, quickly takes effect and lasts 30-45 minutes when given IM to dogs only.
• Atipamezole, an α-2 antagonist, is used to reverse the effects of α-2 agonists like Medetomidine and Dexmedetomidine, administered IM only.
• Diazepam, a GABAa receptor binder (Benzodiazepine), reduces CO, causes muscle relaxation, and has anti-seizure and anti-anxiety effects, administered IV only (given slowly) and lasts 1-4 hours.
• Midazolam, a GABAa receptor binder (Benzodiazepine), is preferred in sick, debilitated, and older patients due to its shorter duration lasting due to inactive metabolites, administered IM, IV, MM (intranasal, rectal).
• Flumazenil reverses benzodiazepines when administered intravenously.
• Morphine, a Mu receptor agonist (opioid), induces sedation, euphoria, bradycardia, vomiting, and defecation, administered IM, SQ or IV, with histamine release, and lasts 4-6 hours.
• Hydromorphone, a Mu receptor agonist (opioid), has effects similar to morphine, lasts 4-6 hours (3-4 hours for acute surgical pain) and administered IV or IM, SQ.
• Fentanyl, a Mu receptor agonist (opioid), is 100 times more potent than morphine, lasts 30 minutes, administered IV, and metabolized by nonspecific esterases.
• Remifentanil, a Mu receptor agonist (opioid), with ↓ potency, and is metabolized by nonspecific esterases.
• Methadone, a pure Mu receptor agonist (opioid), is least likely to cause vomiting and is more expensive, lasting 2-6 hours.
• Butorphanol acts as a Kappa receptor agonist and Mu antagonist, providing mild to moderate visceral pain relief for 30 minutes to 2 hours when administered IV, IM, or SQ.
• Buprenorphine acts as a partial Mu agonist, providing pain control to cats, lasts a LONG duration (4-12 hrs) when administered IV, IM, SQ, or oral transmucosal
• Simbadol is an injectable buprenorphine which lasts 24 hrs when administered SQ.
• Naloxone acts as an opioid antagonist and administered intravenously.
• Propofol, a GABAa receptor binder, induces CNS depression, and decreases blood pressure and respiratory rate, needs to be administered slowly over 60-90 seconds, and recovery should be monitored carefully in greyhounds, when administered IV,
• Ketamine, an NMDA antagonist, induces dissociation and a cataleptic state and rapidly takes effect and lasts 7-23 minutes when administered IV, IM, SQ, IN, or rectally.
• Tiletamine, an NMDA antagonist, is more common in dogs, induces dissociation, and lasts 7-23 minutes when rapidly administered IV, IM, SQ, IN, and rectally.
• Alfaxalone, a GABAa receptor binder, induces CNS depression, vasodilation, and muscle relaxation, and is schedule IV controlled, administered IV or IM.
• Etomidate, a GABAa receptor binder, induces CNS depression and adrenocortical suppression, with quick induction.
• NSAIDs block basal homeostatic function in the stomach, kidneys, and GI tract by blocking the COX enzyme (inhibits PG).
• COX-1 inhibitors block PGs in the brain, spinal cord, neural, repro, and renal systems and other homeostatic functions with a rapid onset of up to 24 hours,.
• COX-2 inhibitors block PGs rapidly effects in the brain, spinal cord, neural, repro, and renal systems and other homeostatic functions with a rapid onset of up to 24 hours.
• Carprofen selectively spares COX-1 while inhibiting COX-2, treats pain and inflammation in OA, ortho, & soft tissue sx, and administered PO or SQ.
• Deracoxib selectively spares COX-1 while inhibiting COX-2, treats pain and inflammation in OA, ortho post-operation, and dental issues, and administered PO
• Firocoxib selectively spares COX-1 while inhibiting COX-2, treats pain and inflammation in OA, administered PO or SQ..
• Meloxicam selectively spares COX-1 while inhibiting COX-2, treats pain and inflammation in OA, only used as a single dose in cats, and administered PO, transmucosally, and parenterally.
• Robenacoxib selectively spares COX-1 while inhibiting COX-2, treats pain and inflammation in OA, good for cats and only use it for 3 days , administered PO, SQ.
• Grapiprant is a non-COX-inhibiting PG antagonist that blocks the EP4 receptor and treats pain and inflammation in OA specifically, administered PO.
• Acetaminophen is not an NSAID, is an antipyretic, and is an analgesic.
• Dipyrone weakly inhibits COX-1 & COX-2, administered inj- equine, and caution is required in species with co-morbidities
• Flunixin meglumine is a non-selective NSAID for colic treatment and endotoxemia, administered PO or IV ONLY to equines or FA.
• Phenylbutazone is a non-selective NSAID, treats musculoskeletal pain and inflammation, and administered PO or injection in equines.
• Guaifenesin is a muscle relaxant with a sedative for co-administration with IV anesthetics, unclear mechanism, affects brain + spinal cord, and administered IV to equine or ruminants.
• Maropitant is a neurokini-1 receptor antagonist that treats motion sickness (vomiting & nausea), antiemetic, MAC sparing, and administered SQ, IV.
• Ondansetron is a 5HT3 receptor (serotonin) antagonist that prevents vomiting, is less effective than maropitant, administered PO or injection.
• Metoclopramide blocks dopamine D2 receptors, is antiemetic, and is prokinetic, increases gastric emptying and injection administered.
• Famotidine, an H2 antagonist, decreases stomach acid, and administered SQ, IV.
• Diphenhydramine, an H1 antagonist, counteracts histamine effects, given pre-removal of a mast cell tumor, IM administered.
• Omeprazole irreversibly blocks H+/K+ATPase, decreasing gastric acid production .
• Aminocaproic acid is an anti-fibrinolytic agent that reduces post-operative bleeding in greyhounds when clot strength is elevated.
• Desmopressin promotes vWF secretions by replacing vasopressin and reducing urine output, and administered as a nasal spray to mainly dobermans vWF deficiency.
• Dantrolene is a Ryanodine receptor antagonist that acts as a muscle relaxant and used for tx/prevent malignant hyperthermia & exertional rhabdomyolysis.
• Doxapram, administered as drops on the tongue of neonates, is a CNS stimulant used for arousal from sedation/anesthesia by unclear, unclear mechanism.
• Lidocaine CRI, at a dose of 50 ug/kg/min, acts as a local anesthetic, spares MAC, and provides anti-inflammatory and analgesic effects.
• Ketamine CRI, an NMDA antagonist, is used for chronic pain, neuropathies, and combined with an opioid or lidocaine.

Antibiotics

• Cefazolin fights gram positive and negative infections, administered IV slowly over 5 minutes.
• Unasyn- Ampicillin administered IV slowly over 15-30 min.
• Gentamicin fights gram negative bacteria, administered IV slowly.
• K-pen is suited for equine GI issues, administered IV slowly.
• PPG should NEVER be given IV
• Naxcel has a FA

Normal Receptors

• Dopamine is a neurotransmitter associated with the reward system, pleasure, and motivation.
• Ach action decreases Heart Rate and Blood Pressure + SLUDGE.
• α-1 action causes vasoconstriction and is water soluble, so administered IM, IV, MM.
• α-2 action causes vasodilation and muscle relaxation and decreases NE, insoluable, so must be administered IV.
• GABA opens chloride channels, leading to hyperpolarization; Benzos can cause paradox excitement & aggression can occur.
• Ryanodine antagonists ↓ Ca2+ release from SR into cytoplasm.

Overview of atropine and glycopyrrolate as Ach inhibitors and antimuscarinics, and acepromazine as a dopamine antagonist. Includes administration routes, durations, and cautions for cardiac patients.