Fundamentals of Pharmacology for Veterinary Technicians Chapter 14

Home , Orbifloxacin, Sulfadimethoxine

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Table 14-1 Mechanisms of Action of Antibiotic Drugs

Action Effect Drug Examples

Inhibition of cell wall Bactericidal effect by inhibition of an enzyme penicillins, cephalosporins, bacitracin, synthesis vancomycin, carbapenems, monobactams, aminocoumarins

Alteration in cell membrane Bacteriostatic or bactericidal effect; as the polymyxin B permeability membrane permeability is increased, the loss of cellular substances causes cell lysis

Inhibition of protein Bacteriostatic or bactericidal effects due to aminoglycosides, tetracyclines, interference interference with bacterial protein synthesis, chloramphenicol, ﬂ orfenicol, macrolides, but not animal cell protein synthesis or lincomycins, aminocoumarins, diterpines inhibition of the steps of protein synthesis

Interference with metabolism Bacteriostatic effects due to the deprivation of sulfonamides essential material for bacterial metabolism

Nucleic acid impairmentBactericidal effects due to inhibition of nucleic quinolones, ﬂ uoroquinolones acid enzymes

Table 14-2 Classes of Antibiotics and Their Effectiveness

Class of Action of Considerations Examples Antibiotic Antibiotic

penicillins • Inhibit cell wall synthesis • Oral and injectable forms • penicillin V (V-Cillin K®), penicillin G • Bactericidal • Given orally, most procaine (Crystacillin®), penicillin G • Mainly work on gram+ absorption occurs in benzathine with penicillin G procaine bacteria; some gram– with stomach and small intestine (Dual Pen®) amoxicillin, ampicillin, • Rapidly distributed • amoxicillin (Amoxi-tabs®, Amoxi-drops®, ticarcillin, and carbenicillin • Give 1–2 hours before Biomox®, Robamox-V®) • Carbenicillin, ticarcillin, and eating • ampicillin (Polyﬂ ex®, Omnipen®) piperacillin are effective • ampicillin with sulbactam (Unasyn®) against Pseudomonas • amoxicillin with clavulinic acid bacteria (Clavamox®) • ticarcillin (Ticar®) • carbenicillin (Pyopen®, Geocillin®) • cloxacillin (Dari-Clox®, Orbenin-DC®) • dicloxicillin (Dynapen®, Pathocil®) • oxacillin (Add-Vantage®) • piperacillin (Pipracil®) • piperacillin with tazobactam (Zosyn®) • ticarcillin with clavulanate (Timentin®) • hetacillin (Hetacin-K®) • nafcillin (Nafcil®)

cephalosporins • Inhibit cell wall synthesis • Oral and injectable forms • First generation: cephapirin (Cefa-Dri®, • Bactericidal • GI absorption not good; Cefa-lak®), cefadroxil (Cefa-drops®, Cefa- • First generation mainly usually administered tabs®), cefazolin (Kefzol®), cephalexin work on gram+ bacteria, parenterally (Keﬂ ex®) second through fourth • Well distributed to tissues, • Second generation: cefoxitin (Mefoxin®), generation work on gram+ except CNS cefaclor (Ceclor®), cefotetan (Cefotan®), and gram– bacteria with • Vomiting and diarrhea may cefuroxime (Ceftin®) fourth generation having occur when given on empty • Third generation: ceftiofur (Naxcel®, the broadest spectrum stomach Spectramast®, Excenel®), cefovecin (including Pseudomonas) • If animal is allergic to (Convenia®), cefoperazone (Cefobid®), • Can cross placenta penicillin, it may be allergic cefotaxine (Claforan®), cefpodoxine to cephalosporin (Simplicef®), ceftriaxone (Rocephin®) • Fourth generation: cefepime (Maxipime®)

polypeptides • Inhibit either cell wall or • Absorption is poor; used for • polymyxcin B (found in Optiprime® cell membrane synthesis topical infections or wound ophthalmic ointment) • Bactericidal lavage • bacitracin (found in Mycitracin® and Trioptic® ophthalmic ointment)

glycopeptides • Inhibit cell wall synthesis • Treats drug-resistant • vancomycin (Vancocin®) • Bactericidal Staphylococcus spp • Injectable form used in veterinary medicine (Continued )

Class of Action of ConsiderationsExamples Antibiotic Antibiotic

carbapenems • Inhibit cell wall synthesis • Injectable form only • imipenem-cilastatin (Primaxin®) • Bactericidal • Broadest spectrum • meropenem (Merrem®) beta-lactam antibiotic • Used to treat resistant bacteria

monobactams • Inhibit cell wall synthesis • Injectable form only • aztreonam (Azactam®) • Bactericidal • Gram-negative spectrum of activity

aminoglycosides • Inhibit protein • Injectable form only (except • gentamicin (Gentocin®, Garacin®) synthesis[en] neomycin which is topical) • neomycin (Biosol®, Mycifradin®) • Bactericidal (concentration • Not absorbed readily from • amikacin (Amiglyde-V®, Amikin®) dependent) GI tract; usually given • tobramycin (Nebcin®) • Work mainly on gram– parenterally • dihydrostreptomycin (Ethamycin®) bacteria • Nephrotoxicity and • spectinomycin (Adspec®, Spectam®) • Can cross placenta ototoxicity concerns • Do not mix with penicillin in the same syringe (makes penicillin inactive)

tetracyclines • Inhibit protein synthesis • Oral and injectable forms • tetracycline (Panmycin Aquadrops®, • Bacteriostatic • Once given, quickly Oxy-Tet 100® injectable, Tetracycline • Work on gram+ and distributed, sometimes to HCl® soluble powder) gram– bacteria, as well CNS • oxytetracycline (Terramycin®, as rickettsial bacteria, • Very little metabolism Liquamycin®) spirochetes, and some • Bind to calcium, causing • chlortetracycline (Aureomycin®) protozoa side effects (do not give • doxycycline (Vibramycin®, Doxirobe® Gel) with dairy products or • minocycline (Minocin®) antacids/antidiarrheal drugs) • demeclocycline (Declomycin®) • Can cause yellow discoloration of teeth due to calcium binding

chloramphenicol • Inhibits protein synthesis • Oral, injectable, and • chloramphenicol (Chloromycetin®, • Bacteriostatic ointment forms Viceton®, Amphicol®) • Works on gram+ and • Readily absorbed into tissues gram– bacteria as well as • Side effect of bone marrow rickettsial bacteria suppression makes use not recommended

fl orfenicol • Inhibits protein synthesis • Injectable form • fl orfenicol (Nufl or®) • Bacteriostatic • Well distributed in body; can achieve therapeutic levels in the CNS

macrolides • Inhibit protein synthesis • Well distributed to most • tilmicosin (Micotil®) • Bactericidal or body tissues, but not the • tylosin (Tylan®) bacteriostatic CNS • erythromycin (Erythro-100®, Erythro-Dry®) • azithromycin (Zithromax®) • tulathromycin (Draxxin®)

(Continued )

Table 14-2 (Continued ) Class of Action of ConsiderationsExamples Antibiotic Antibiotic

lincosamides • Inhibit protein synthesis • Recommended for • clindamycin (Antirobe®) • Bactericidal or abscesses and dental • pirlimycin (Pirsue®) bacteriostatic infections • lincomycin (Lincocin®)

aminocoumarins • Inhibit protein and nucleic • Used as a combination • novobiocin/tetracycline/prednisolone acid synthesis; also product in dogs (Delta Albaplex®) interferes with cell wall • Used as a mastitis • novobiocin/penicillin G procaine (Albadry synthesis treatment in dry dairy cattle Plus®) • Bactericidal • novobiocin (Biodry®) • Works mainly on gram+ bacteria

diterpines • Inhibit protein synthesis • Premix, solution, and • tiamulin (Denagard®) • Bacteriostatic powder formulations • Works on gram+ cocci • Used to treat pneumonia in and limited gram– swine bacteria

sulfonamides • Inhibit folic acid synthesis • Can have anti-infl ammatory • sulfadiazine/trimethoprim (Tribrissen®) • Sulfonamides are effects • sulfadimethoxine (Albon®) bacteriostatic • Well distributed through the • sulfadimethoxine/ormetroprim (Primor®) • Trimethoprim and ormetro- body, including eye and CNS • sulfasalazine (Azulfi dine®) prim are bactericidal and and synovial fl uid • sulfamethoxazole with trimethoprim used to potentiate sulfas • Can cause increased (Bactrim®) • Potentiated sulfas are salivation in cats bactericidal

fl uoroquinolones • Inhibit DNA function • Readily absorbed into • enrofl oxacin (Baytril®) • Bactericidal tissues and body fl uids • orbifl oxacin (Orbax®) after oral and parenteral • difl oxacin (Dicural®) administration • marbofl oxacin (Zeniquin®) • sarafl oxacin (SaraFlox®) • ciprofl oxacin (Cipro®) • danofl oxacin (Advocin®)

nitrofurans • Inhibit bacterial enzyme • Eliminated from body • nitrofurazone (Furazone®, NFZ Puffer®) systems quickly; usually used in • nitrofurantoin (Macrodantin®) • Bactericidal urinary tract infections • furazolidone (Topazon®, Furox®) • Banned for use in food- producing animals

nitroimidazoles • Disrupt DNA and nucleic • Well absorbed after oral • metronidazole (Flagyl®) acid synthesis administration • Bactericidal • Use with caution in pregnant animals

rifampin • Disrupts RNA synthesis • Relatively well absorbed • rifampin (Rifadin®, Rimactane®) • Bactericidal or from GI tract bacterioistatic depending • Can cause red urine, tears, on dose sweat, and saliva • Usually used in combination with other antibiotics

Table 14-3 Classes of Antifungals and Their Effectiveness

Class Mechanism of Considerations Examples Action

polyenes Bind to fungal cell membrane Not well absorbed; fairly toxic• amphotericin B (Fungizone®) • nystatin (Panalog®)

imidazoles Cause leakage of fungal cell Less toxic; used for systemic • ketoconazole (Nizoral®) membrane mycotic infections and some • miconazole (Monistat,® Conofi te®) dermatophyte infections • itraconazole (Sporanox®) • fl uconazole (Difl ucan®) • voriconazole (Vfend®)

antimetabolics Interfere with RNA and Used mainly in combination • ﬂ ucytosine (Ancobon®) protein synthesis with other antifungals to treat Cryptococcus infections

superﬁ cials Disrupt fungal cell division Used for dermatophyte • griseofulvin (Fulvicin-U/F®, Grifulvin V®) infections • terbinaﬁ ne (Lamasil®)

Table 14-4 Types of Disinfectants and Antiseptics

Disinfectant Product Use ActionComments Group Examples

phenols and • ortho-phenylphenol Laundry, Moderately • Action not affected by organic phenolics (Lysol®, Amphyl®, ﬂ oors, walls, bactericidal, material Tek-Trol®, 1 Stroke equipment virucidal, and • Used as a 2–5% solution on Environ®) fungicidal contaminated objects • hexachlorophene (Phisohex®)

quaternary • didecyl dimethyl Instruments, Moderately • Action not affected by hard water ammonium ammonium chloride rubber, bactericidal, compounds (Roccal®-D) inanimate virucidal, and • benzalkonium chloride objects fungicidal (Zephiran®) (Continued )

Disinfectant Product UseActionComments Group Examples

aldehydes • gluteraldehyde Instruments Highly bactericidal, • Action not affected by organic (Cidex®, Glutarol®) virucidal, and material or hard water fungicidal

• ortho-phthalaldehyde Instruments Highly bactericidal, • All items processed with aldehydes (Cidex-OPA®) virucidal, need to be rinsed with water prior to use tuberculocidal

• formaldehyde Tissue biopsies Highly bactericidal, • Use in areas of good ventilation and footbaths virucidal, • Avoid skin and eye contact and inhalation of vapors tuberculocidal

alcohols • 70% isopropyl Instruments Highly bactericidal, • 70% solution usually used some virucidal •A 50% ethyl alcohol Thermometers action, and • ffected by organic material and dirt action

halogens • chlorines: (Chlorox®) Chlorines: Moderately • Corrosive to surfaces; ﬂ oors, cages to highly • Vapors can be irritating • Iodine tincture is about 2% virucidal, • iodophors: Iodophors: moderately to • Iodine tincture is about 2% ® ® (Betadine , Povidine ) presurgical highly fungicidal, scrub, and some sporicidal thermometers activity

biguanide • chlorhexidine Skin wounds, Highly bactericidal, • Residual action of about 24 hours (Nolvasan®, presurgical moderately due to binding to skin Hibiclens®, Virosan®) scrub, oral virucidal, and poorly cleaning fungicidal solutions, and cages

ethylene oxide Rubber goods, Highly bactericidal, • “Gas sterilization” for objects blankets, virucidal, and that cannot withstand and lensed fungicidal heat instruments • Carefully read MSDS prior to handling • Keep away from ﬂ ames and sparks

oxidizing agents • hydrogen peroxide Cleaning Moderately to • Causes oxygen release, which kills • peracetic acid wounds and highly bactericidal, anaerobic bacteria (Virkon®S) ﬂ oors, foot virucidal, and • Action not affected by organic bath fungicidal matter or hard water