Michael Walzer y sus contradicciones nacionalistas

a. To improve growth rato and/or feed conversion-efficiency b. Widely used in poultry, swine, intensively-reared cattle 2. Virginiamycin

a. One of the depsopeptide group of antibiotics b. Isolated from Streptomyces virginiae

c. MOA: Interferes with protein synthesis by distorting the ribosomal A site to inhibit the binding of aminoacyi tRNA and the peptidyltransferase reaction

d. Mainly active against gram positive anaerobic and aerobic bacteria? also vs, Leptospira, Treponema hyodysenteriae, Haemophilus, Mycoplasma

e May exhibit cross-resistance with macrolides and lincosamides f. Used in pig and poultry

3. lonophore antibiotics a. MOA:

1) It complexes with sodium in the cell membrane to cause the passive transport of potassium ions out of the cell in exchange for hydrogen ions 2) The low intracellular pH kills the cell

b. Monensin

1) Fermentation product of Streptomyces cinnamonensis 2) Active primarily against gram positive bacteria and coccidia 3) Primarily used as an anticoccidia in poultry

4) Used to improve feed conversion efficiency in ruminants 5) Fatal when used with tiamulin

6) Horses are susceptible to toxic effects of ionophores c. Salinomycin

1) Anticoccidial activity

2) Improves efficiency of ruminal fermentation

3) Used as growth promoter in swine 4) Fatal when combined with tiamulin d. Others: Lasalocid, Maduromycin, Narasin 4. Tiamulin

a. A pleuromutilin

b. Used as growth promoter in swine 5. Macrolidae antibiotics

a. Brythromycin - growth promotion in cattle and swine b. Spiramycin - growth promotion in calves

c. Tyiosin - promote growth and improve weight gain in swine; poultry and ruminants

6. Quinoxalines

a. Quinoxaline NN dioxide derivative existing DNA (similar to that of nitrofurans) b. MOA: Inhibit bacterial synthesis an denature pre-existing DNA (similar to that of nitrofurans)

c. More effective in anaerobic condition

d. Active vs. Clostridia and Treponema, Chlamydia, and protozoan q. Examples: Carbadox, Olaquindox

7. Bacitracin Zinc - growth promotion and disease prophylaxis in cattle and swine 8. Lincomycin - used in pig and poultry

9. Hitrofurans a. Nitrofurazone

1) Poorly soluble and not absorbed after oral administration

2) Used as feed additive (0.051) to control enteric bacteria and coccidiosis b. Furazolidone

1) Has the greatest antibacteral activity among nitrofurans 2) Poorly soluble and not absorbable after oral administration 3) Also used for prevention of coccidiosis in poultry

10. Others: Bambermycin, Avilamycin, Flavomycin, Avoparcin, Arsenical:: (Arsanilic Acid, Sodium Arselinate), Mitrovin, Halquinol

ANTIVIRAL AGENTS

1. ANTIVIRAL CHEMOTHERAPY

a. Still in an early stage of development but has excellent long-term prospects

b. Most of antiviral drugs used in humans as experimental drugs in human medicine are still further investigated for their potential veterinary use.

2. Mechanisms of action of various antiviral agents a. Inhibition of penetration of cells

b. Inhibition of intracellular viral protein synthesis c. Inhibition of virus assembly or release

d. Inhibition of assembly of viral particles e. Immunoenhancers

3. Inhibition of penetration to cells a. Gamma Globulins

1) Passive immunization in IgG (IM, IV, SC) can prevent entry of viruses into cells 2) Protection may last for several weeks butnot completely

3) May be used to control distemper, rabies, Aujesky's disease, TGE in swine

4) Offsprings that have taken colostrum from vaccinated dams are usually protected from enteric viral infections

b. Araantadine

1) A synthetic tricyclic araine with a symmetric structure . 2) Activity limited to Influenza A viruses in humans and animals

3) Most effective as^prophylactic; moderately effective early in the course od disease 4) Experiments as porphylactic in infected chickens and turkeys proved successful 4. Inhibition of intracellular viral protein synthesis a« Inhibition of early protein synthesis:benzimidazoles

1) Formation of RNA polymerase in inhibited 2) Ready development of resistance

b. Inhibition of nucleic acid synthesis 1) Idoxuridine - vs. herpesvirus

a) Converted into an iodonalogue of thymidilate b) Inhibit virus-specified DMA polymerase

c) Defective viral proteins will be produced d) Topical use only

e) Used for treatment of feline herpesvirus

keratoconjunctivitis and herpatic keratitis in other species 2) Viradarabine

a) An analogue of adenine deoxyriboside b) Acts by inhibiting viral DNA polymerase

c) Effective /vs. viruses with DMA polymerase activity

d) Low solubility and rapid systemic deamination makes it unsuitable for systemic use in animals

3) Ribavirin

a) Resembles guanosine and interferes with formation of guanosine phosphate in DNA and RNA viruses

b) Has broad antiviral activity vs. many DNA and RNA viruses c) Clinical used does not induce viral resistance

c) Clinical use does not induce viral resistance d) Low toxicity upon systemic administration

e) Prolonged treatment in cats may produce profound thrombocytopenia 4) Acyclovir

a) An acyclic nucleoside analogue of 2- deoxyguanosine b) One of the first new antivirals lincensed for use in humans

c) Highly effective vs. herpesvirus by inhibiting herpes-specified DNA polymerase d) Potential in veterinary medicine needs further studies

5) Ganciclovir

a)/ Active bs. all herpesviruses

b) More active than ancyclovir vs. cytomegalovirus c) Outstanding activity vs .fequine herpesvirus

6) Trifluridine

a) A halogenated thyroidine analogue

b) Drug of choice for herpetic keratitis because of superior ability to penetrate the cornea

7) Iodothyronine

a) A dideoxynucleoside thymidine analogue

b) Inhibits viral reverse transcriptase in retroviral replication

c) HIV reverse transcriptase 100 x moresusceptible than mammalian DNA polymerase

d) Prolongs survival in advanced cases if HIV-AIDS by 12-30 months and delays progression of asymptomatic infection

e) Tested in FeLV and FIV infections 8) Phosphonofornate (Foscarnet) a) A pycophosphate analogue

b) Inhibits DNA polymerase of herpesvirus and RNA polymerase of influenza viruses being investigated for treatment of herpesvirus infections and AIDS in humans c. Inhibition of late protein synthesis:

Methisazone

1) Inhibits transcription of proteins required for development of mature virus 2) Effective prophylactically vs. poxviruses (vaccinia, small pox)

3) Possible use as prophylactic in infectious canine hepatitis and bovine respiratory disease

5. Inhibition of virus assembly or release: 2-Deoxy-D-Glucose

a. Inhibits a wide range of enveloped DNA and RNA viruses (esp, .orthonyxo-, paramyxon, and herpesviruses)

b. A glucose analogue

c. Interferes with the synthesis of oligosaccharides that are part of viral specific surface glycoproteins

d. Results to decreased infectivity of viruses because of their inability to penetrate cells or to become uncoated. Topically applied on to genital herpes in women

f. Potential application as prophylaxis in CD, equine influenza, and parainfluenza infections

6. Interferons

a. Families of glycoproteins with antiviral, immunomodulatory and antiproliferative effects b« Produced most animal species

c. Indirect antiviral activity: alter host metabolism to impair synthesis and assembly of viral components

d. Immunomodulating activity:

1) Increased antibody production 2) Increased natural killer activity

3) Enhanced antigen expression on cell enhances recognition of virally infected cells e. Types: alpha (leukocyte) amd beta (fibroblast) are released in response to antigen or nitrogen stimulation

f. Clinical application still under study

g. Studies have also been conducted to stimulate endogenous interferon production but has not yielded satisfactory results

7. Inhibition of assembly of viral particles; Rifampin

a. Inhibits DNA-dependent RNA polymerase in bacteria and mammalian cells b. Prevents assembly of enveloped mature particles in mammalian cells in poxviruses c. Effect is reversible upon remova.. of drug

8. Immunoenhancers a. Cytokines

b. Inosiplex (Inosine Pranobex) 1) Claimed to

a) Increase B and T lymphocyte activity b) Increase natural killer cell activity

2) No evidence of its value in veterinary medicine c. Bacterial adjuvants

1) Both Bacilus Calmette-Guerin (BCG) AMD Corynebacterium parvum are nonspecific adjuvants that increase activation- of macrophages through an effect on T lymphocytes

2) Others require additional study ANTIFUNGAL AGENTS

A. CLASSIFICATION OF FUNGAL INFECTIONS