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Contraindicated antibiotics in small animals
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Antimicrobials contraindicated in Antimicrobials contraindicated in canines and felines, reasons and canines and felines, reasons and
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K. Karthik, 1689
Introduction
• Antimicrobials may not act in the same way in all species of animal
• Antimicrobials- the remedy for many infectious agents- can cause serious damage at times
• Choice of antibiotic is critical• Dogs and Cats- companion animals- can over
react to certain antimicrobials.
Antimicrobials and associated problems
Antimicrobials Associated problems
Tobramycin, spectinomycin, Gentamicin
Neuromuscular & renal toxicity, oto toxicity
Chloramphenicol and griseofulvin, cefachlor/ cefadroxil/ cephalexin/ cepharadine
Diarrhoea and vomiting
Enerofloxacin/ ciprofloxacin/ norfloxacin
Nephrotocity, diarrhoea
Erythromycin/ clindamycin/ lincomycin
Vomiting, diarrhoea and hepatotoxicity
Nitrofurans and rifampin Hepatotoxic, discolour tears and urine
Ketoconazole, itraconazole Anorexia, depression, dirrhoea, vomiting
SulphonamidesCrystalluria – Sulphathiazole • Sulpha metabolized by acetylation mainly
• Acetylation reduce solubility
• Leads to Crystalluria
• More common in dehydrated animals, acidic urine (carnivores)
• Dogs- lack acetylation mechanism so problem is less.
• Counter act: urinary alkalizers, enough intake of water
Triple sulpha powder ( Sulphapyridine, sulphamerazine, sulphadiazine)- more solube
Hypersensitivity• Sulphadiazine- produce reversible
immune mediated sterile polyarthritis – Doberman
• Can occur 8-20 days after start of treatment
• Backs to normal within 5 days after halt of therapy
Sulfasalazine- for chronic colitis treatment
Colon
Hydrolyzed by bacteria
Sufapridine (Antibiotic) + 5 amino Slicylic acid (anti inflammatory)
Dose – 25 mg/ kg/day
This dose can cause salicylate poisoning in cats
Keratoconjunctivitis sicca – Dogs more prone
• Sulphasalazine, sulphadiazine and sulphamethoxazole
• Nitrogen containing pyridine ring acts on lachrymal acinar cells – cause dryness
• Lacrimation may not return to normal after discontinuation
NN44
Hemorrhagic syndrome
• Sulfaquinoxaline – as anti malarial• Vitamin K antagonist - similar to that
of coumarin anticoagulants• Rapid hypoprothrombinemia occur in
dogs • Hypoprothrombinemia can occur
within 24 hours of treatment
Cephalosporin• Cats – superinfection or anaemia• Ceftiofur in dogs - Anemia and
thrombocytopenia• Vomiting, Diarrhoea• Cephaloridine – most nephrotoxic Is a Zwitter ion
Enters proximal tubules
Affects S2 segment- renal failure
AminoglycosidesNephrotoxicity• Aminoglycosides are +ve charged
• Attracted to –ve charge of lipid layer of kindney
• Transported by pinocytosis, related to phosphotidyl inositol ( high in renal and cochlear)
• Acidic pH increase interaction and divalent cations reduce it.
• Reduced prostaglandin synthesis – low glomerular filtrate
• Initial stage- reversible; prolonged usage- irrversible
Neomycin˃ Tobramycin ˃ Gentamicin < Neomycin˃ Tobramycin ˃ Gentamicin < DihydrostreptomycinDihydrostreptomycin
Lysosomes
Mitochondria
Rupture of lysosome
Brush border cells
Ototoxicity- irreversible• Vestibular and cochlear dysfunction• Accumulates in peri and endolymph of
inner ear- elimination slow• Streptomycin> GentamicinStreptomycin> Gentamicin –
Vestibulotoxic• Neomycin>Kanamycin>amikacinNeomycin>Kanamycin>amikacin –
ototoxic• Cats more susceptible than dogs
Fanconi’s syndrome
• Defective transport of water, salts, bicarbonate, and amino acids from the kidneys; impaired tubular reabsorption.
• Common in Basenji breed of Dogs
Neuromuscular blockade• Interfere with Ach release from motor ending• Not commonly seen in therapeutic dosage• When administered with general anaesthesia
and neuromuscular blocking agents.Neomycin, Streptomycin>kana>amika>gentaNeomycin, Streptomycin>kana>amika>genta• Tobramycin least
Thought on aminoglycosideThought on aminoglycosideAminoglcosides- reserved for G(-)ve infections,
used only when benefit overpowers adverse effects
TetracyclineGI upset• Anorexia, abdominal pain, diarrhoea,
nausea and vomiting (Doxycycline)• Super infection with fungi and bacteria• Cardiovascular dysfunction-
Tetracycline chelates calcium. Rapid infusion in i/v causes hypotension and collapse.
• Cats- Fever• Discoloration of teeth
Chloramphenicol
• Cats- dose-related blood dyscrasias• If treatment is nearly 14 days• Longer elimination half-life in the cat• Hypersensitivity reaction in dogs and
cats –Aplastic anemiaReversible bone marrow depression• Kittens – deficient microsomal
enzymes- inadequate drug metabolism- lead to bone marrow suppression.
• Avoided to nursing bitches, queens.
Macrolides
• GI effect• Dogs – i/v erythromycin- increase in
the electrical and motor activity of the stomach
• Increases gastric motility• Diarrhoea, Vomiting
Quinalones
Arthropathy• Common in pups and kittens• Heavy dog breeds- permanent damage to
joints• Due to chelation of Mg2+ in cartilage • Enroflaxacin @5 to 25 mg/kg for 30 days-
pupps and kittens - splitting of the articular cartilage
• Marbofloxacin, Orbifloxacin- large breeds of dogs- cats resistant to Orbifloxacin effect
Retinal degenerationAcute blindness, mydriasis- enro - 20 mg/kg a day in cats
• Difloxacin and orbifloxacin- Anorexia, decreased appetite, diarrhea, or vomiting
• Enrofloxacin and orbifloxacin- ataxia, seizures
• Orbifloxacin- hypersensitivity
Lincosamide
Anorexia, diarrhea, vomiting• Local irritation of abdominal mucosa
by oral dosing• Lip smacking and excess salivation in
cats with clindamycin
Metronidazole
Neurological disturbances- ataxia, nystagmus, seizures, tremors, weakness
• Rifampin and nitrofurans- colours urine red
Antifungal
Amphotericin –nephrotoxic• Causes renal vasoconstriction, binds to
membrane cholesterol in renal tubules• Cats more sensitiveGriseofulvin:• Hepatotoxic, CNS disturbances,
hemolytic alterations• Kittens commonly affected- inadequate
glucuronyl conjugation
Cats- terato and carcinogenic in high doseCats- terato and carcinogenic in high dose
Ketaconazole:• Hepatotoxic. Cats> dogs• Decrease libido in males-
suppression of testosterone
Renal failure Hepatic Pregnancy Neonates
Aminoglcosides Chloramphenicol Aminoglcosides Aminoglcosides
Amphotericin B Clindamycin Amphotericin B Chloramphenicol
Chloramphenicol- cats
Griseofulvin- cats Azithromycin Quinalones
Quinalones Ketaconazole Chloramphenicol Metronidazole
Lincomycin Lincomycin Fluconazole Nalidixic acid
Nitrofurantoine Macrolide Flucytosine Rifampin
Polymyxin Metronidazole Quinalone Polymyxin
Sulphonamides Rifampin Griseofulvin Sulpha
Tetracycline except doxy
Sulphonamides Ketaconazole Trimethoprim
Tetracycline Sulpha Tetracycline
Polymyxin
Trimethoprim
Metronidazole
Nitrofurantoine
Antimicrobials Antimicrobials contraindicated in contraindicated in different conditionsdifferent conditions
Safer antibiotics
Kidney disorder- Penicillin, tetracycline, cephalosporin
• Reduce the dose of drug and increase frequency
Hepatic damage- Amox, Ampicillin• Cephalosporin- next choice• Metronidazole- can be given at lower dose
Neonates- beta lacatm safe
Pregnancy safe
• Drugs safe in pregnancy- betalactam antibiotics (penicillin G, ampicillin, amoxicillin, amoxicillinclavulanic, carbenicillin, ticarcillin, and cephalosporins)- I choice
• Macrolides, and lincosamides (clindamycin, erythromycin, and lincomycin) – used in allergic patient
Fluroquinalone- not in the line of Fluroquinalone- not in the line of treatment of pregnant animalstreatment of pregnant animals.
Conclusion
• Every antibiotic has their own benefits and problems
• Selection of antibiotic according to the state of disease, species, status of the animal
• Beta lactams are safer compared to all other antibiotics in most of the situations
Thank youThank you
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