Pharmacology

drugs that kill or inhibit growth of microorganisms such as bacteria, protozoa, viruses, and fungi

kills microorganism

inhibits growth of microorganism

(basically starving the microorganism to death)

antimicrobials produced by a microorganism

synthetic, toxic to bacteria

kill microorganism without killing patient

• Minimum Inhibitory Concentration
• lowest concentration at which growth of the bacterium is inhibited 

(how susceptible is a bacterial strain?^)

• low #-strong antibiotic
• high #-weak antibiotic

(ex:MIC for Penicillin may be higher than MIC for Amoxicillin. the MIC changes as time goes on and the bacteria become more and more resistant to the antibiotic)

• antibiotics in feed over long periods (ex: Strongid T)
• failure to admin for appropriate period of time (never use antibiotics less than 5 days)
• failure to consider pharmacokinetics of drug (ex: renal infections, drug have to be admin for extended periods of time)

• cell wall- lyse wall&kill bacteria. effective only in growing bacteria
• cell membrane permeability-penetrates cell wall and membrane by bringing about death inside the cell once entered (but does not destroy cell wall)
• ribosomes-block protein synthesis by interfering with sequence of amino acids and thus protein development
• critical enzymes- drug attach to enzymes needed in the conversion of food&growth products thus starving to death (ex:bacteriostatic)

• nucleic acids
• these drugs damage the nucleic acid production of a bacteria, preventing it from normal division
• these drugs usually take longer to work/kill
• ex: antiprotozoan/antifungal products

• penVK
• ampicillin
• amoxicillin
• hetacillin
• cloxacillin

• cell wall lysis
• effective against gram + bacteria (not beta-lactamase)
• procaine&benzathine- vehicles
• broad&narrow spectrum
• belongs to group B-Lactam Drugs

either intensify or lengthen effect of drug

kills gram+ and -

(narrow kills one or the other)

act by disrupting bacterial cell wall synthesis

inclues penicillins, cephalosporins, etc.

most common mechanism of bacterial resistance to B-lactams is production of B-lactamase enzymes which damages the B-lactam ring of these compounds and renders them ineffective.

these organisms are classified as methicillin-resistant types and compromise a majority of nosocomial isolates from human&some animal hospitals

infections inside an otherwise sterile area

(infection at hospital)

beta-lactamase (penicillinase)

beta-lactamase-resistant/penicillinase resistant penicillins: some penicillins are more resistant to beta-lactamase-hydrolysis

gram-positive bacteria

but gram-negative bacteria have an outer membrane around the cell wall that limits permeability (ex: methicillin, cloxacillin, dicloxacillin, oxacillin)

• Penicillin G sodium
• Penicillin G potassium
• Penicillin G procaine
• Penicillin G benzathine

Penicillin V

• Methicillin
• Cloxacillin
• Dicloxacillin
• Oxacillin

• Ampicillin
• Hetacillin
• Amoxicillin
• Carbenicillin

Amoxicillin

tetracyclines & chloramphenicol

tetracylines & chloramphenicol

methicillin, cloxacillin, dicloxacillin- tetracyclines& chloramphenicol

oxacillin- sulfonamides

chloramphenicol, erythromycin, tetracyclines, cephalosporins

chloramphenicol, erythromycin, tetracyclines, cephalosporins

chloramphenicol, erythromycin, tetracyclines, cephalosporins

anti-emetics like apomorphine or syrup of ipeca

kidney

therefore, kidneys BUN and Creatinine must be checked in geriatric animals

Penicillins are excreted through the milk in small amounts

Staphlococcus agalactiae

Epinephrine 1:10,000 IV

comes 1,000 mg per mL--reconstitute to 1 mL of epi per 10 mL water (will kill by IV if not)

long acting (48-72 hrs)

not normally approved for use in dairy animals

• polyflex (ampicillin injection)
• penicillin G procaine or benzithine injection
• ambi-pen injection
• amoxi-tabs&clavamox tabs for dogs&cats

• ceph/cef prefix
• similar to penicillins
• bacteriocidal
• susceptible to beta-lactam
• broad spectrum, more effective against gram+ bacteria
• classified by generations

higher the generation=more gram neg. effectiveness

• major risk- allergy to penicillin also allergic
• minor risk- nephrotoxic

Cephalexin (Keflex)

Cefaclor (Ceclor)

Cefixime (Suprax)

Ceftazidime (Fortaz)

Cefepime (Maxipime)

*IV only*

any product containing gentamicin

tetracycline

• cefa-drops
• cefa-tabs
• cefa-lak (mastitis treatment)
• naxcel powder for injection
• excenel injectable suspension

adverse side effects: nausea, vomiting, diarrhea, lethargy

• proteus
• pseudomonas (most resistant-use polymyxin B, Gentamicin)
• pastuerella
• klebsiella

Polymyxin B

• antimicrobial effective against gram+ bacteria
• topical--dissolves well into dermis
• often combined with other antibiotics for broad spectrum effect (ex: triple antibiotic ointment contains bacitracin, polymyxin B, neomycin)OTC

bacteriostatic unlike penicillin&cephalosporin

• developed from gram neg bacteria
• broad spectrum
• bacteriocidal
• includes: gentamicin, amikacin, neomycin, streptomycin, dihydrostrep, apramycin, kanamycin, tobramycin
• nephrotoxic&ototoxic in felines
• to prevent nephrotoxicity in animals other than feline, IV fluids must be admin simultaneously
• combine with ribosomes interfering with amino acid sequence
• be careful with--very toxic!

sulfonamides

• erythromycin
• tetracycline
• cephalosporins
• chloramphenicol

because they are not readily absorbed through GI tract

neomycin administered orally bc it is not absorbed at all. thus, can be accurately administered by weight for infections of GI tract&be assured that 0% is lost in the tissues surrounding the tract (ex: Neo-pectalin--oral absorbant)

• bacteriostatic
• one of oldest antibiotics
• binds to ribosomes disturbing amino acid
• first antibiotic broad spectrum (gram+&-, as well as mycoplasmas, spirochetes, chlamydia)
• precautions: chelates with minerals of developing tooth enamel&bones imparting a yellow discoloration, use cautiously with impaired liver function

• permanent staining of teeth if received in utero or as juvenile
• drug is also deposited in growing bones, slowing their development

presence of food, milk products, antacids 

• Oxytetracycline
• Chlortetracycline
• Doxycycline
• Minocycline

diuretics, antacids, milk, penicillins (DAMP)

(shock&diarrhea can occur if given IV in horses)

diuretics, antacids, milk, penicillins (DAMP)

• diuretics, antacids, milk, penicillins (DAMP)
• same as barbituates

diuretics, antacids, milk, penicillins (DAMP)

• bacteriostatic in low doses
• bacteriocidal in high doses (unique)

penetrates CNS (blood-brain barrier), prostate gland, globe of eye, etc due to the fact that in high doses it exceeds the MIC

• precautions: anorexia in cats
• banned in food animals
• gray babies in humans
• vehicle with barbituates

blood dyscrasias in cats after prolonged treatment

• penicillin
• streptomycin
• cephalosporins

• Lincomycin
• Clindamycin

chloramphenicol

• gram-positive
• anaerobic

dentals (ex: Antarobe)

• Erythromycin
• Tylosin (Tylan)

• binds to ribosomes with no aa sequencing
• will penetrate many tissues but not CNS

Erythromycin

sulfanomides 

interfere with formation of folic acid, so effective against bacteria that form their own folic acid

• gram-positive
• gram-negative
• coccidia

yes

animal has ample amounts of water bc will precipitate out in kidneys and cause dryness of cornea and keratoconjunctivitis

Fluoroquinolones

damage nucleic acid production of bacteria preventing bacterium from normal division

Fluoroquinolones

(especially in gram-positive rods in dogs,cats,fowl,cattle--not horse)

• Enrofloxacin (Baytril)
• Orbifloxacin (Orabax)
• Ciprofloxacin (Cipro)-for anthrax ppl only

• gram-positive
• gram-negative
• pseudomonias (gn)
• aeromonas
• beta-lactam bacteria

(good broad spectrum)

fluoroquinolones

enrofloxacin

• ciprofloxacin
• enrofloxacin
• difloxacin hydrochloride
• orbifloxacin
• sarafloxacin
• marbofloxacin
• norfloxacin
• pradofloxacin

ciprofloxain

difloxacin

Marbofloxacin

norfloxacin

pradofloxacin

Veraflox (pradofloxacin)

formation of lesions in joint articular cartilage during rapid growth phase of dogs

Metronidazole

(commonly prescribed with corticosteroids for IBD and periodontal disease)

Metronidazole

an antibacterial/antiprotozoal agent commonly used to treat protozoal infections and anaerobic bacterial infections. also has marked antiinflammatory effect on bowel.

fungal infection

• topical (superficial)- affecting skin and mm
• systemic- affecting blood, lungs, or CNS

Amphotericin B

• antifungal drug
• fungistatic or fungicidal
• mixed with D5W to decrease nephrotoxicity
• IV
• breaks down membrane wall for early death

• used for yeast to systemic funguses
• can effect testosterone production in male

topical application to treat dermatophytes and yeast

• low dose-fungistatic
• high-cidal

• "Exelderm"
• better than miconazole
• effective topically against ringworm (Microsporum canis)

• oral&topical
• most commonly used for Candidas albicans infections of the skin

• oral
• antifungal effective against dermatophytes
• easily absorbed in skin/nails especially with oils/fats in diet
• should never be given to pregnant-monsters and cleft palates can result

more of "immuno stimulants"

include: amantadine, ganciclovir, idoxuridine, azidothymidine