Critical care drugs

Abstract

PHOTOS 1-3: Ampoules are small, hermetically sealed glass or plastic containers which may contain medication for parenteral administration or semen for insemination. Pramalon and Ondansetron are antiemetics that are available in ampoules. PHOTO 4: A suspension is a preparation of undissolved substance in a liquid vehicle. Lacson syrup is an oral suspension used for the relief of constipation. PHOTO 5: Sodium bicarbonate is used as a gastric antacid and a systemic and urinary alkalinizer. It can also be used locally to remove mucus, exudates and scabs. Sodium bicarbonate is used for the alkalinization of urine in carnivores as it increases the elimination rate of long acting barbiturates. Administration of sodium bicarbonate to animals with lactic acidosis may improve tissue perfusion but risks causing overshoot metabolic alkalosis. PHOTO 6: LAXETTE [Medpro Pharmaceutica (Pty)Ltd] is a sweet-tasting, colourless to yellow-brown solution that is presented in 150mL and 500mL amber glass bottles or 2,5L amber or white plastic containers. 5mL of LAXETTE contain 3,3g lactulose. Lactulose is an osmotic cathartic that is normally used to prevent and treat hepatic encephalopathy in dogs, cats and birds by reducing blood ammonia concentration. It can also be used to treat chronic constipation in dogs, cats and reptiles. It is a synthetic derivative of lactose and cannot be digested by enzymes of the mammalian and probably not by the avian digestive tract. Upon reaching the colon, lactulose is metabolized by the gut bacteria forming organic acids and CO2.These acids cause a laxative effect by increasing osmotic pressure and drawing water into the intestinal lumen. Furthermore, it causes acidification of the colon content that in turn cause ammonia to migrate from the blood to the colon where it is excreted with the faeces. Adverse effects of the drug include flatulence, gastric distension, cramping and diarrhoea. This drug must be used cautiously in patients with pre-existing fluid and electrolyte imbalances and water should be made freely available to patients treated with this drug. Cats dislike the taste of lactulose making administration difficult. The drug is not readily absorbed by the gastrointestinal tract and most of it is excreted unchanged in the urine within 24 hours. Lactulose may also be known by the synonym lactulosum. PHOTO 7: Atropine (0.5 mg/mL and 10 mg/mL, Centaur) is a muscarinic receptor antagonist. Muscarinic receptor antagonists block the binding of acetylcholine to muscarinic receptor cholinergic receptors on smooth and cardiac muscle, gland cells, peripheral ganglia and the central nervous system. Atropine is a naturally occurring substance that can be found in the plants Atropa belladonna (deadly nightshade) and Datura stramonium (jimsonweed). It generally causes relaxation of bronchial, biliary and urinary tract smooth muscle but also has excitatory effects on the central nervous system. Effects of the substance are dose dependant. Small doses of atropine inhibit salivary and bronchial secretion and sweating. Increased doses cause pupils to dilate and blocks vagal effects to the heart leading thereby to increased heart rate. Larger doses inhibit micturition and decrease tone and motility of the gut and may even completely inhibit gastric motility and secretion. Atropine is often used as an addition to anaesthesia to increase heart rate and decrease respiratory and gastro-intestinal secretions. It can also be used as an antidote for organophosphate poisoning. Atropine should not be used in patients with glaucoma, intestinal ileus, gastroparesis or tachycardia. Certain species like the rabbit have an enzyme, atropine esterase, which allows these animals to rapidly metabolize the drug. PHOTO 8: SYNULOX® RTU is a schedule 4 broad spectrum antibiotic [Pfizer Laboratories (Pty)Ltd]. In vitro it is active against a wide range of clinically important gram-positive and gram-negative bacteria and it has been clinically shown to be effective in treating a wide range of disease conditions of cattle and small mammals. SYNULOX® RTU injection contains 35mg/mL clavulanic acid and 140mg/mL amoxicillin. Clavulanic acid is naturally produced by Streptomyces clavuligerus and competitively and irreversibly binds to beta-lactamases and penicillinases. Amoxicillin is penicillin that inhibits mucopeptide synthesis in the cell wall resulting in a defective barrier. After shaking the vial to suspend the active ingredients, it can be injected by the subcutaneous or intramuscular route. Clavulanic acid is moisture sensitive, so dry syringes must be used for injection. It is contra-indicated in known cases of hypersensitivity to penicillins and other related compounds and should not be used in rabbits, guinea pigs, hamsters or gerbils. SYNULOX® RTU injection is a smooth, off-white to pale buff coloured fluid presented in 50mL or 100mL clear glass vials. PHOTOS 9-11: The active ingredient found in Flagyl® Suspension (Aventis Pharmaceuticals) is metronidazole, an antibacterial and antiprotozoal agent. It is active against most obligate anaerobes and can be used to treat both enteric and systemic anaerobic infections. It does however, have no effect on aerobic bacteria. Metronidazole has been used extensively by veterinarians in the treatment of Giardia in dogs and cats. In addition, metronidazole has therapeutic activity against Entamoeba histolytica, Trichomonas and Balantidium coli. This drug is also effective against anaerobic osteomyelitis and can be used as preventive treatment for lower gastro-intestinal surgery. Although adverse effects of the drug are uncommon, vomiting, nausea and inappetence may occur. Cats often salivate profusely after administration. Metronidazole is also a potential teratogen and should therefore not be used during pregnancy, especially during early pregnancy, unless the benefits outweigh the potential risks to the foetus. This drug must be used with caution in animals with hepatic dysfunction. PHOTO 12: Intravenous administration of antibiotics may be necessary when a patient becomes critically ill or when an infection becomes life-threatening. PHOTO 13: Ulsanic suspension is used to relieve and prevent gastritis, reflux, oesophagitis and peptic ulcers in humans. Each 5ml contains 1g sucralfate, a compound used to prevent and treat gastric and intestinal ulceration and gastritis in animals. It is also commonly used by veterinarians to treat non-steroidal anti-inflammatory drug (NSAID) induced ulcers. Ulsanic suspension must be stored in a cool (below 25°C), dry place. PHOTO 14: The active ingredient found in Kortico is dexamethasone. Dexamethasone is a synthetic adrenal steroid with glucocorticoid activity and little mineralcorticoid activity. Dexamethasone can be used to induce parturition in many domestic species by administering it intramuscularly or subcutaneously during late gestation. Dexamethasone mimics the foetal cortisol and action on the placenta in the same fashion. Adverse effects are associated with long-term administration and are generally manifested as symptoms of hyperadrenocorticism. It can also retard growth in young, growing animals. PHOTO 15: Ropivicaine is a long acting local anaesthetic with a high efficacy and potency but lower central nervous system and cardiovascular system toxicity than other local anaesthetics. Ropivicaine is vasoconstrictive if injected at low concentrations and has vasodilating effects at higher concentrations.

REFERENCES: PHOTOS 1-3: King, L & Hammond, R (eds) 1999, ‘BSAVA manual of canine and feline emergency and critical care’, British Small Animal Veterinary Association, Cheltenham, pp.303-304. PHOTO 4: Blood, DC, Studdert, VP & Gay, CC 2007, ‘Saunders comprehensive veterinary dictionary’, 3rd ed., Saunders Elsevier, New York, pp. 1734. PHOTO 5: 1. Adams, HR (ed) 2001, ‘Veterinary pharmacology and therapeutics’, 8th ed., Iowa State University Press, Ames, pp.520-521. 2. Blood, DC, Studdert, VP & Gay, CC 2007, ‘Saunders comprehensive veterinary dictionary’, 3rd ed., Saunders Elsevier, New York, pp. 1661. PHOTO 6: 1. South African Electronic Package Inserts 1996-2009, Laxette solution, viewed 9 July, 2010, http://home.intekom.com/pharm/cipla/laxette.html 2. Adams, HR (ed) 2001, ‘Veterinary pharmacology and therapeutics’, 8th ed., Iowa State University Press, Ames, pp. 1056-1057. 3. Maddison, JE, Page, SW & Church DB (eds) 2008, ‘Small animal clinical pharmacology’, 2nd ed., Saunders Elsevier, Philadelphia, pp. 495-496. 4. Plumb, DC 2005, ‘Plumb’s veterinary drug handbook’, 5th ed., Blackwell Publishing, Ames, Iowa, pp. 450-451. PHOTO 7: 1. Brunton, LL, Lazo, JS & Parker, KL (eds) 2006, ‘Goodman & Gillman’s the pharmacological basis of therapeutics’, 11th ed., McGraw-Hill Medical Publishing Division, New York, pp. 1748-1749, 1763. 2. Rang, HP, Dale, MM, Ritter, JM & Flower, RJ 2007, ‘Rang and Dale’s pharmacology’, 6th ed., Churchill Livingstone, Edinburgh, pp. 153-154. 3. Katzung, BG (ed) 1995, ‘Basic and clinical pharmacology’, 6th ed., Appleton & Lange, Norwalk, pp. 102-107. 4. Papich, MG 2007 ‘Saunders handbook of veterinary drugs’, 2nd ed., Saunders Elsevier, St. Louis, pp. 49-50. PHOTO 8: 1. Pfizer South Africa 2006, Synulox® RTU, viewed 9 July, 2010, http://www.pfizer.co.za/Knowledge/pkDownloadDocument.aspx?docid=2988 2. Plumb, DC 2005, ‘Plumb’s veterinary drug handbook’, 5th ed., Blackwell Publishing, Ames, Iowa, pp. 41, 45. 3. Hardman, JG, Limbird, LE, Molinoff, PB, Ruddon, RW & Gilman, AG (eds) 1996, ‘Goodman & Gilman’s the pharmacological basis of therapeutics’, 9th ed., McGraw-Hill, New York, p. 1097. 4. Maddison, JE, Page, SW & Church DB (eds) 2008, ‘Small animal clinical pharmacology’, 2nd ed., Saunders Elsevier, Philadelphia, pp. 164-165. 5. Giguére, S, Prescott, JF, Baggot, JD, Walker, RD & Dowling, PM (eds) 2006, ‘Antimicrobial therapy in veterinary medicine’, 4th ed., Blackwell Publishing, Ames, Iowa, pp. 162-163. PHOTOS 9-11: 1. Plumb, DC 2005, ‘Plumb’s veterinary drug handbook’, 5th ed., Blackwell Publishing, Ames, Iowa, pp. 228-232. 2. Maddison, JE, Page, SW & Church DB (eds) 2008, ‘Small animal clinical pharmacology’, 2nd ed., Saunders Elsevier, Philadelphia, p. 183. 3. Barragry, TB 1994, ‘Veterinary drug therapy’, Lea & Febiger, Philadelphia, p. 481. PHOTO 13: Riviere, JE & Papich, MG (eds) 2009, ‘Veterinary pharmacology and therapeutics’, 9th ed., Wiley Blackwell, Ames, Iowa, pp.1258-1259. PHOTO 14: 1. Maddison, JE, Page, SW & Church DB (eds) 2008, ‘Small animal clinical pharmacology’, 2nd ed., Saunders Elsevier, Philadelphia, pp. 527. 2. Barragry, TB 1994, ‘Veterinary drug therapy’, Lea & Febiger, Philadelphia, p. 481. 3. Plumb, DC 2005, ‘Plumb’s veterinary drug handbook’, 5th ed., Blackwell Publishing, Ames, Iowa, pp. 228-232. PHOTO 15: Riviere, JE & Papich, MG (eds) 2009, ‘Veterinary pharmacology and therapeutics’, 9th ed., Wiley Blackwell, Ames, Iowa, pp. 395.