Drug therapy Flashcards
Hartmanns
Balanced, isotonic, buffered solution
Hypertonic saline (7%)
Very high osmolarity
Used for rapid fluid resuscitation
(Can use colloids - stay in vascular compartment, keep fluids in vascular)
Shock dose
90ml/kg/hour over 15 min (dogs)
60-70ml/kg/hour over 15 min (cats)
Case by case adjustment
Reassess
Glucocorticoid
Specific group of corticosteroids that act on inflammatory system and will have other metabolic effects
Glucocorticoid mechanism
Bind to specific intracellular receptors Alter gene expression Alter regulation of many cellular processes Increase their own metabolism Decrease cortisol proudction
Why are glucocorticoids better at suppressing inflammation than NSAIDS?
Suppress T-lymphocyte functions
Inhibit monocyte - macrophage activities
Suppress fibroblast functions and collagen deposition
Reduce histamine release from mast cells
Decreased synthesis of lymphokines
Metabolic duration
Short acting 48h): flumethasone, dexamethasone, betamethasone
Fluticasone proprionate
Inhalant therapy for asthmatic inflammation
Inhaler, face-mask, deep constant flow
Atypicals
Rickettsia Mycoplasma Chlamydia Borrelia Bartonella Mycobacterium
Minimum inhibitory concentration
Lowest concentration of drug that will inhibit bacterial growth
MIC90 - therapeutic dose to kill 90% of a bacteria
Inhibition of cell wall synthesis
Penicillins
Cephalosporins
Bacitracin
Inhibition of cell membrane function
Polymyxins
Amphotericin B
Imidazoles
Nystatin
Inhibition of protein synthesis
Chloramphenicol Macrolides Lincosamides Tetracyclines Aminoglycosides
Inhibition of nucleic acid synthesis
Sulphonamides Trimethoprim Quinolones Metronidazoles Rifampin
Bacteriostatic
Chloramphenicol Lincosamides Macrolides Tetracyclines Non-potentiated sulponamides
Bacteriocidal
Time dependent vs Concentration dependent
Penicillin Cephalosporins Aminoglycosides Fluoroquinolones Potentiated sulphonamides (TMPS) Metronidazole
Time dependent
Time above MIC over 24h period predicts therapeutic success
Penicillins, cephalosporins, TMPS
Bacteria must be multiplying (don’t combine with bacteriostatic)
Concentration dependent
Peak concentration achieved or area under the curve predicts therapeutic success
Aminoglycosides, fluoroquinolones, metronidazole
Effective against dormant bacteria (can combine with bacteriostatic)
Red antibacterial
No useful activity against the vast majority of bacteria i a quadrant
Green antibacterial
Excellent activity against most bacteria in this quadrant
Blue antibacterial
Good activity against many bacterial species in this quadrant but some important species resistant
Brown antibacterial
Moderate activity against bacterial species in a quadrant - some susceptible, some resistant
1st gen cephalosproins, cefovicin and amoxycillin (no clav) against gran negatives aerobes and obligated anaerobes
Lincosamides other than clindamycin against anaerobes
TMPS in all quadrants
Tetracyclines in all quadrants (except gram positive) - excellent activity against atypicals
Gram-positive aerobes
Penicillin G Aminopenicillins Cephalosporins Lincosamides/Macrolides Tetracyclines Rifampin Fluoroquinolones
Gram negative aerobes
Fluoroquinolones Aminoglycoside 2nd/3rd generation cephalosporins (not cefovicin) Ticarcillin-clavulanate Amoxy-clav
Obligate anaerobes
Penicillin G Amoxy-clav Clindamycin Metronidazole Chloramphenicole Rifampin
Penicillinase-producing Staph
Amoxy-clav 1st/2nd gen Cephalosporins (and cefovicin) Cloxacillin Fluoroquinolones Rifampin Clindamycin
Intracellular bacteria
Bartonella Brucella Chlamydophila Mycobacterium Rickettsia Staphlococcus
How well do antimicrobials penetrate?
Poor: pencillin, cephalosporins, beta lactamase inhibitors, polymixins, aminoglycosides
Good: Suphonamides, trimethoprim, lincoasmides macrolides, tetracycline
Great: Chloramphenicol, fluoroquinolones, lipophilic tetracyclines (moxycycline, doxycycline), metronidazole, rifampin
Environmental conditions affected anti-microbials
Haemoglobin - decrease pencillin efficacy
TMPS - inactivated by pus
Erythromycin, clindamycin, fluoroquinolones - low pH causes reduced activity
Urinary infections
Which antibiotic?
Usually gram negative or mixed infection
If prostate involved (usually in entire) - need good penetration
TMPS good option - excreted in urine
Amoxycillin(-clav) good option in bitches
Kennel cough with systemic signs
Causative agent: Bordetella - Gramnegative
Amoxy-clav, tetracyclines, TMPS
Strangles
Causative agent: Streptococcus equi equi - Gram positive
Quarantine livery yard
Penicillin - good against early signs - treat all mildly affected/exposed horses
Once developed submandibular abscesses, don’t use penicillin!
- Flush abscesses
- Supportive care
- No antibiotics
- Quarantine for at least 4 weeks
Complicated form:
- Bacteria spread through other lymph nodes
- Long term antibiotics (penicillin or TMPS)
Systemic inflammatory reponse
H
Stabilise
Septicaemia
Peritoneal tap +/- ex lap and lavage
Fluroquinolone + metronidazole to cover all four quadrants until results back from culture and sensitivity
Bacterial meningitis (calf) Which antibiotic?
Florphenicol
- Good penetration
- Good against gram negatives
- Safe to use in young production animals
PLACE
Small Mammals
Penicillin Lincosamides Aminoglycosamides Cephalosporins Erythrofloxacin
FINE TO MEDICATE
Small Mammals
Fluoroquinolines (Baytil)
TMPS
Metronidazole
Mare - salmonella
Aerobic gram negative - aminoglycoside
Penicillin can lead to overgrowth of clostridium
Cat bite abscess
Open, flush, close with drain
Gram negative anaerobes most likely in an abscess but consider contamination from skin (gram positives)
Clindamycin, metronidazole, amoxy-clav
Deep pyoderma
Can be Pseudomonas or Staphylococcus
Should take skin scrape and look for rods and send for culture and sensitivity
Topical therapy?
Amoxyclav, 1st/2nd generation cephalosporin, fluoroquinolone
Toxic mastitis
E. coli - gram negative (or Strep uberis, Staph aureus)
Need systemic treatment
- Cephalosporins 2nd/3rd - not great penetration, intramammary?
- Amoxy-clav?
Carprofen (and flunixin) have effects against endotoxaemia
Drugs not to use in production animals
Enrofloxacin in layers
Chloramphenical
Metronidazole
Mucolytics
Bromhexine - alters mucus viscosity
Dembrexine - alters secretory activity of glands
Assist the removal of mucus plugs
Expectorants
Said to be of limited therapeutic value
Oral e.g. ipecacuana and squill - irritate mm and caused increased clearance of mucus
Inhaled e.g. eucalyptus oil - increase secretion of watery mucus
Nasal decongestants
Pseudoephedrine:
- Indirectly acting sympathomimetic
- Decreases blood flow to secretory glands, reducing mucus production
Use: URT conditions associated with profuse secretion e.g. allergic rhinitis in cats
Bronchodilators
Muscarinic receptor agonists
Atropine, ipratopium
Inhibition of vagally-induced contraction of airway smooth muscle
Adverse effects: inhibition of mucociliary clearance, inhibition of GIT function, CNS stimulation
Bronchodilators
Beta-adrenoreceptor agonists
Beta2-selective drugs (Beta2-agonists):
- Clenbuterol (horses, cattle)
- Terbutaline (cats and dogs)
- Salbutamol, salmeterol (horses - inhaled)
Relaxation of airway smooth muscle by activate of beta2 receptors
Other properties:
- Inhibition of vascular permeability and swelling
- Inhibition of cell activation
- Improve mucociliary clearance
Adverse effects: tachycardia, hypotension, sweating, restlessness/excitation, muscle tremors, hyperkalemia
Non-selective drugs: Epinephrine, emergency treatment, isoprenaline
Bronchodilators
Methylxanthines
Theophylline, etamiphylline Unclear mechanism: - Phosphodiesterase inhbition - Adenosine antagonism - Anti-inflammatory effects - Direct stimulation of respiratory centres in CNS
Renal and circulatory effects may improve respiratory function in some conditions
Adverse effects: tachycardia, restlessness/excitability, vomiting
Bronchodilators
Uses
Infection/inflammation of the respiratory tract
Allergic respiratory disease
Chronic obstructive pulmonary disease (COPD)
Airway inflammation drugs
Anti-inflammatory:
- Glucocorticoids
- NSAIDs
- Methylxanthines
- Histamine, serotonin, leukotriene
- (Prophylactic) sodium cromoglycate and nedocromil
Prokinetics
Metoclopramide
Carbachol etc.
Laxatives
Liquid paraffin: lubricate
Stimulant: senna
Bulk forming: wheat bran, methylcellulose
Osmotic: lactulose, magnesium sulphate, sodium sulphate, enema
