Flashcards in Final Exam Drugs Deck (93):
Appetite stimulants. Cyproheptadine (Effective in cats, given orally, can cause sedation) and Mirtazapine (MOA: blocks 5HT1 and 5HT2 receptors, used more in dogs).
A Phenothiazine. Blocks dopamine receptors in the CNS. Effects: sedation, moderate muscle relaxation, no analgesia, hypotension. Reduced hematocrit and antihistamine (H1 antagonists).
Contraindicated with vasodilation. Boxers more sensitive to CV effects. Stallions can have penile prolapse and injury (paraphimosis). Not approved in food animals because can cause ruminal regurgitation. Aggressive dogs may startle easily. Excited patients may have reduced effect. Contraindicated in liver disease. Do not have concurrent administration of epinephrine.
MOA: Potentiates GABA receptors. Effects similar to propofol. Neurosteroid which is an analog of progesterone. Does not bind to usual "steroid" receptors (no glucocorticoid, mineralocorticoid, or sex hormones effects). Approved (class IV controlled substance). Labeled for IV usage only. Similar pharmacokinetics to propofol but no accumulation seen. Full anesthesia, no analgesia.
NMDA antagonist sometimes used as adjunctive analgesic in small animals. Also oral drug.
Amide Local Anesthetics
Metabolized by the liver - Lidocaine, Bupivacaine, Mepivacaine, Ropivacaine
Impair nucleic acid synthesis (DNA) in rapidly dividing immune cells and block T-cell signaling. Azothioprine, Mycophenolate mofetil, and Leflunomide.
Mostly used an an emetic in dogs. Considered another opioids. Stimulates dopamine receptors. Can be given by all routes. Used in dogs. Overdose can lead to respiratory depression. Can reverse with naxolone but this will not reverse emetic effect.
Natural tear is 3 layers (mucin, water, and lipid film). "Lacrimomimetic agents" provide lubrication but do not perfectly replicate natural tears.
COX-1 selective inhibitor aka Acetylsalicyclic acid
Atipamezole and Yohimbine
Reversal - Alpha-2 Antagonists. Atipamezole high alpha 2 selectivity. Match receptor affinity ratio to the alpha 2 agonist used. Usually to reverse sedation (small animal) or when adverse events occur. Analgesia will also be reversed!
Spontaneous degradation (no liver/kidney involvement). Non-depolarizing NM blockers. Competitive antagonism with Ach for nicotinic receptors at the motor end plate; causes flaccid paralysis. Given IV. Poor penetrators of membranes. More potent in horses.
Direct acting parasympatholytic (mydriasis). Causes cycloplegia (blurred vision), this can cause horses to panic. Indicated to reduce pain associated with corneal or iris disease (uveitis) or to break up synechiae in uveitis. DO NOT USED IN PRIMARY GLAUCOMA! Cats froth at the mouth due to bitter taste.
Antimetabolite used for immunosuppressive therapy. Use with prednisone. DO NOT USE IN CATS (toxicity for liver/bone marrow). Oral medication. Ester LA - Used topically. Allows for corneal and conjunctival manipulation. Rapid onset and short duration.
MOA: Act by stimulating GABA and inhibiting the satiety center to increase appetite. More effective in cats than dogs. Generally short term use only. Most common side effect is sedation. Diazepam and Midazolam.
Alpha agonists. Ophthalmic alpha agonist. Sometimes used in dogs to treat glaucoma. Not most likely choice.
Salt/chemical compounded into pills or liquid (KBr from most common). Unknown MOA but raises seizures threshold by competing with Cl- transport. Long half-life; once a day administration. Must use loading dose or it will take 8-9 weeks to reach effective levels. Dogs on high salt diet may need higher dose because high Cl- increases Br loss in urine and lowers serum concentration. Not metabolized by liver - good for patients with hepatopathies. As effective as phenobarbital. Avoid in cats (asthma). PU/PD, sedation, pancreatitis, ataxia, rear limb weakness, dysphagis, megaesophagus.
Frequently used. 0.5% solution for injection. Amide LA. Slow onset and long duration. MOST cardiotoxic of the LAs and more potent than lidocaine. Diazepam may increase cardiopressant effects.
Partial u agonists. Semi-synthetic opioid. Ceiling effect - more potent than morphine but less max effect because it is a partial agonist. Less negative effects than morphine. Slower onset and longer duration than morphine. IV, IM , SC, transmucosal. Useful for at-home analgesia, especially in cats.
Mixed agonist/antagonist. Synthetic k agonist and u antagonist. IV, IM, SC, PO. Analgesia in cats, dogs and horses. Antitussive in dogs. Better for visceral pain than somatic. Commonly used in equine. Used in small animals to "partially" reverse a full mu agonist. Lower ceiling effect.
Carprofen, Meloxicam and Deracoxib
COX-2 preferential. Commonly used in small animal medicine as analgesics and anti-inflammatory agents. Available in a variety of oral options (tablets, liquids, transmucosal oral spray) and injectable (SQ). Meloxicam is approved for SINGLE injection use in cats.
Antacid H2 blocker, inhibit gastric acid and pepsin secretion, competitive inhibition of H2 receptor. Low potency, short duration. Inhibits microsomal enzymes.
Serotonin 5HT4 agonists. Increases PNS input; Only available by compounding; used to treat megacolon and megaesophagus in cats.
COX-1 Selective Inhibitors
Aspirin/Acetylsalicyclic acid (ASA)
COX-2 Preferential Inhibitors
Deracoxib, caprofen, meloxicam
COX-2 Selective Inhibitors
Alpha-2 Agonists. Very good sedation, good muscle relaxation, mild analgesia, and mild respiratory depression. Emetics in cats (cats have more a2 and less D2 receptors). Used for dogs, cats and exotics. Highest alpha 2 selectivity.
Diazepam and Midazolam
Benzodiazepines. Bind to and activated benzodiazepine binding site on GABA receptors to cause hyperpolarization of neurons. Effects: Mild sedative, good muscle relaxation, no analgesia, minimal cardio respiratory effect, anticonvulsant, appetite stimulant.
Diazepam: Usually given IV, can be given orally. Can cause hepatic necrosis in cats. Painful IM injection because it contains propylene glycol.
Midazolam: can be given IM (or IV or orally).
Topical Carbonic Anhydrase Inhibitors. Reversible inhibition of CA - decreases aqueous humor. Dorzolamide + Timolol = Cosopt.
Ester Local Anesthetics
Hydrolyzed by plasma esterases - Procaine and Proparacaine
Antacid H2 blocker, inhibit gastric acid and pepsin secretion, competitive inhibition of H2 receptor. More potent, longer duration, less enzyme inhibition than cimetidine.
U agonist. Synthetic opioid, extremely potent. Rapid onset and short duration. Can give as transdermal patch. Lag time to onset, lasts a few days.
COX-2 selective. Oral paste for horses, chewable tablets for dogs. Commonly used in SA medicine as analgesics and anti-inflammatory agents.
Benzodiazepine antagonist. Used for reversal in the rare cases it is necessary.
Large animal NSAID (lots of adverse effects in SA). Used for soft tissue disease in horses. Only NSAID labeled for cattle (control of pyrexia associated with bovine respiratory disease, endotoxemia and acute mastitis). Muscle necrosis with IM administration. Anaphylaxis seen rarely after IV administration.
Flurbiprofen and Diclofenac
Topical NSAIDs. Use when a higher local concentration and lower systemic concentration is desired. Used in management of uveitis and some keratitis. May be used in patients to manage inflammation associated with cataracts. Contraindicated in corneal ulcerations, glaucoma, or coagulopathies.
Used for control of neuropathic pain (e.g. phantom limb pain). Alters Ca influx in neuronal cells. May cause sedation/ataxia, frequent dosing required. Do not use human oral liquid in dogs.
Antiviral agent. Most often used to manage feline viral infections (e.g. herpes) and generally reserved for more severe cases. Potential adverse effects (bone marrow, hepatic and renal toxicity). Greater risk with systemic antivirals.
Glucocorticoids (Dexamethasone and Prednisolone)
Avoid unless necessary for anti-inflammatory therapy. Use lowest effective dose. Use prednisone. First choice is high dose for immunosuppressive therapy. Taper over weeks/ months with monitoring once disease is under control. Side effects common. Contraindicated for corneal ulcers, infection, or diabetes. For Ophthalmics - Use when a higher local concentration and lower systemic concentration is desired.
Centrally acting muscle relaxant acting on the spinal cord. MOA: depresses nerve impulses in the spinal cord, brainstem and subcortical areas of the brain to cause centrally mediated muscle relaxation. Used during anesthesia in equine/bovine/swine. No significant effect on respiratory function.
Usually given IV to horses and cattle. Short onset and duration. Crosses placenta but does not harm fetus. "Triple dip"" - Guaifenesin + a2 agonist (Xylazine or Detomidine) + ketamine. 5% solution recommended because causes thrombophlebitis with 10% (cattle more sensitive than horses).
Other opioid. Antitussive, not usually used as an antitussive.
U agonist. Less histamine release, used IV in place of morphine, similar onset and duration as morphine. Semi-synthetic opioid.
New AED available in UK and Australia. MOA: partial agonist at benzobiazepine binding sites on GABA receptors. Similar to diazepam. Less tolerance and addiction potential than full benzodiazepine agonists. Fewer adverse effects than phenobarbitol.
Immunosuppressive Therapy - Cyclosporine
Blocks cyclophilin to reduce T-cell activation and response, inhibit production of cytokines and alters WBC function. Used topically on eye to treat keratoconjunctivitis sicca. Used systemically to treat perianal fistulas or as adjunct to glucocorticoids immunosuppressive therapy. Side effects - GI upset, gingival proliferation, nephrotoxicity and hepatotoxicity.
Immunosuppressive Therapy - Tacrolimus
Used for dermatologic disease such as perianal fistulas. Blocks cyclophilin to reduce T-cell activation and response, inhibit production of cytokines and alters WBC function.
Indirect Acting Parasympathomimetics
Physostigmine, Demecarium, Echothiopate. Increases uveoscleral drainage.
Dissociative anesthetic (dissociate thalamocortical and limbic systems resulting in a catatonic state where the eyes remain open and swallowing reflexes remain function). NMDA receptor channel blockade - inhibits activation by glutamate of these ligand-gated ion channels and may have other effects. Full analgesia, no muscle relaxation, can cause bronchodilation. Usually given IV or IM. Catalepsy, pain with IM injection, can have rough recovery if used alone. Respiratory depression at high doses. Can also cause muscle tremors and hypertonicity, CNS stimulation and convulsion and vomiting/hypersalivation.
Antifungal that inhibits steroid synthesis pathway. Questionable efficacy. Risk of hepatotoxicity.
Topical prostaglandin analogs. Increased uveoscleral outflow by stimulating FB (prostaglandin receptors). Topical to treat glaucoma and reduce IOP.
Antimetabolite used for immunosuppressive therapy. Oral drug, few side effects
Pyrrolidine derivative. Unknown MOA; thought to bind to pre-synaptic vesicle protein and alter release of neurotransmitters to inhibit seizure generation. Can be used as primary AED or add-on. 70-90% excreted unchanged in urine. Very safe with few side effects. Rarely can have sedation and decreased appetite. Little to no monitoring necessary. Short half life so more frequent dosing required expensive.
Most commonly used. Amide LA. Do not exceed 4-7 mg/kg (total dose). Sheep are most sensitive, cats more sensitive than dogs. Can be used for local analgesia as 1-2% solution for injection or as 4% solutions topically. EMLA cream - 2.5% lidocaine/2.5% prilocaine. Also class IB antiarrhythmic (used to control ventricular arrhythmias/ tachycardia), adjunctive analgesia, or GI prokinetic/anti-inflammatory.
Cause reversible blockade of transmission in peripheral nerves or spinal cord, usually to stop pain signals. Work through blockade of voltage gated sodium channels in nerve axons. Preferentially bind drugs in open or inactivated state, not in resting state.
Decreases GI motility. It is an opioid. Has a faster onset and longer duration of action in dog, but avoid in dogs with MDR-1/ABCB-1 mutation. MOA: Action central and peripheral opioid receptors to inhibit propulsive motility, increase segment motility and inhibit defecation reflex. Decreases GI motility.
Anti-emetic. NK receptor antagonist. Labeled for prevention of motion sickness in dogs or treatment of acute vomiting in dogs and cats. Stings on injection.
Amide LA. Used for diagnostic nerve blocks in horses. Similar to lidocaine but less irritating.
Also a muscle relaxant. Exact MOA not known; works centrally, used in dogs, cats and horses. Oral or injectable. IV or PO in cats and dogs. IV in horses.
Clinical uses: NOT WITH ANESTHESIA. Intervertebral disk disease. Functional urethral obstruction/urinary retention. Poisoning with tetanus, strychnine and other agents that cause spastic paralysis. Irritating with given IV (DO NOT GIVE IM/SC). Sedation/weakness/ataxia. May darken urine (incidental finding).
Anti-emetic, dopamine antagonist and also blocks 5HT3 at higher doses and is also a prokinetic. More potent anti-emetic than the phenothiazines. Antagonizes apopmorphine induced emesis. Available as oral or injectable (intermittent SC or IV CRI).
MOA: Inhibits cAMP resulting in decreased protein kinase activity and hydrogen ion concentration but less potent than H2 or PPI. Increase mucus and sodium bicarb secretion and stimulates ulcer healing (COX-1). Used to treat NSAID-induced gastric ulcers. Abortifacient; can stimulate uterine contraction. Can cause diarrhea.
Cytotoxic to adrenal glands. Narrow therapeutic index. Start with high dose (induction) and then reduce to lower dose (maintenance). Over treatment can cause Addison's. Monitor with ACTH stim test.
U agonist, natural opioid, pre-anesthetic and pain management. Risk of histamine release with IV (esp. in dogs). Prototypical analgesic, onset 5-15 mins and last several hours, used in epidurals (preservative free)
Antimetabolite used for immunosuppressive therapy. Less commonly used, often reserved for immune diseases that are unresponsive to other treatments. Given orally.
Phenylephrine - Perioperterative use in cataract surgery, diagnose and treatment of Horner's syndrome.
Full antagonists. Competitive receptor antagonist used for reversal of opioid induced adverse effects (e.g. respiratory, CNS depression). Rapid onset (minutes) and short duration (1-2 h) - repeated doses may be needed until the opioid is gone. Will reverse the analgesic effects as well!
Antivfungal agent. Less frequently used than antibiotics. Treatment of fungal keratitis, conjunctivitis. This is the human labeled product. Numerous compounded or extra-labeled products used.
Nonspecific COX Inhibitors
Flunixin, ketoprofen, phenybutazone
Non-Steroidal Anti-inflammatory drugs. Caprofen, flunixin meglumine, phenylbutazone, Firocoxib, Robenacoxib. COX-2 inhibitors. Special use: Aspirin, Piroxicam.
Proton Pump Inhibitor (PPI). MOA: Irreversibly inhibit H/K/ATPase proton pump resulting in decreased hydrocholoric acid production. More portent than H2 blockers. Raise gastric pH. Oral only. Labeled for equine.
Serotonin antagonists (5HT3 receptors). Anti-emetic. Act centrally and peripherally. Initially used for chemotherapy related nausea. More potent than metoclopramide, but more money. Usually given by injection but oral formula is available.
Ophthalmics - Cyclosporine
Topical immunomodulators ("Lacrimogenic agents"). Treatments of canine keratoconjunctivitis sicca. BID lifelong application. Monitor tear production with Schirmer test. Local immunosuppression.
Ophthalmics - Tacrolimus
Topical immunomodulators ("Lacrimogenic agents"). Decreases T-cell activation. Alternative to cyclosporine (works on different receptors). Potential cancer link - wear gloves).
Barbiturate. Used mostly for euthanasia. Given IV. Never give a product intended for euthanasia for any other indication because it may contain impurities.
Dopamine agonist --> decreased ACTH --> decreased cortisol. Used to treat pituitary pars intermedia dysfunction in horses.
Acute therapy to stop a seizure in progress. Slower onset and longer duration than benzodiazepines. May be used concurrently for longer duration of control (but caution of additive adverse effects). MOA: Potentiate GABA receptors. Enters CNS readily. Tolerance often develops; may need to increase dose. Cytochrome p450 induction. Can be loaded to achieve rapid blood levels. Safe, cheap, best choice drug for dogs and cat. PU/PD, sedation, hepatotoxicity, addiction possible. Dosage adjusted on the basis of history of seizure control and serum level.
Commonly used in horses to treat musculoskeletal pain. Given PO or IV. Do not give IM or SC, can cause sloughing and necrosis. Intracarotid injection can cause seizures/CNS stimulation. Can mask lameness; withdrawal time for racing animals.
Direct acting parasympathomimetics (miotics). Direct acting. Miosis lasts 2-6 hours. Treatment of glaucoma or for diagnosis of parasympathetic lesions. Sometimes used to treat keratoconjunctivitis sicca (Dry Eye).
Antineoplastic effect - COX-2 expressed by a number of cancers.
Ester LA. You won't use procaine as a LA, but it is in some penicillin G preparation. Toxic, can cause CNS stimulation - excitement, seizures - DON'T GIVE IV!
Ophthalic topical analgesia. Blocks Na+ channels to prevent axonal depolarization. Typically used to decrease corneal sensation to allow diagnostic evaluation (e.g. tonometry).
Considered a barbiturates (thiopental) that affects GABA (inhibitory neurotransmitter). Analgesia and AED. Used PO or IV. Management of seizures. Good oral bioavailability in dogs. Metabolized primarily in the liver. Hepatic microsomal enzyme inducer. MOA: Potentiates GABA receptors and inhibition of 5HT. Effect seen at sub-hypnotic doses. Full anesthesia, no analgesia. Decreases intracranial and intraocular pressure. Given IV - rapid onset and short duration of action. Widely distributed to all tissues (lipid soluble). Can cause Heinz body formation in cats with repeated dosing. Excitement at induction with some horses. Front leg stiffness and paddling sometimes seen.
Antacid H2 blocker, inihibit gastric acid and pepsin secretion, competitive inhibition of H2 receptor. Also have some prokinetic activity
COX-2 selective. The first NSAID approved for multiple doses (SID up to 3 days) in cats.
Non-depolarizing NM blocker. A special NMB that has a specific reversal agent. Very fast onset and can be terminated with sugammadex.
Amide LA. Less cardiotoxic S enantiomer
Increases dopamine --> decreased ACTH --> decreased cortisol. Labeled for treatment of canine cognitive dysfunction. Sometimes used to attempt to treat Cushing's.
Depolarizing (noncompetitive) NM blocker. Activates nicotinic Ach receptors at motor end plate but causes a prolonged depolarization. Muscle fasciculations are caused by repeated firing followed by flaccid muscle paralysis. Not metabolized by acetycholinesterase like ACh is but just diffuses away from the NMJ.
Give IV (poor oral absorption). DOA = 2-3 min. Hydrolyzed by plasma pseudocholinesterases in plasma and liver. Can also cause: transient bradycardia, increased IOP due to contraction of ocular muscles. Hyperkalemia due to K+ release from skeletal muscles. No specific reversal. If there is a problem give supportive care until metabolized.
MOA: Binds to ulcer site and protect it against acid, pepsin and bile. Requires acid environment to bind to mucosal blood flow. Poorly absorbed; few side effects. Can see constipation.
Used for immunosuppressive therapy. Cyclosporine and tacrolimus topical.
Non selective. Beta antagonist used to decrease formation of aqueous humor and help reduce intraocular pressure and manage glaucoma. Used to prevent glaucoma in contralateral eye. Some miosis.
Weak u agonist but also serotonin and NE reuptake inhibitor. Oral analgesic. May lower seizure threshold, avoid in epileptic patients.
Currently most commonly used to treat Cushing's. Competitive inhibitor of steroid synthesis. Narrow therapeutic index (minimal problems when used appropriately). Monitor ACTH stim test. Used to inhibit the enzyme that is part of the cortisol production pathway.
Direct acting parasympatholytic (mydriasis). Causes cycloplegia. Faster onset, shorter duration than atropine. Used to dilate pupil for ophthalmic exam. Used to prevent adhesion after cataract surgery. Less effective pain control than atropine. Less bitter but can still cause hypersalivation in cats. AVOID IN GLAUCOMA. May alter Schirmer's tear test in cats and horses.
Alpha-2 Agonists. Very good sedation, good muscle relaxation, mild analgesia, and mild respiratory depression. Emetics in cats. Species sensitivity: cattle > camelids > small ruminants > cat/dog/horse > swine > rodents. Not used in dogs/cats much (increased morbidity. Lowest alpha 2 selectivity.