Q 3: veterinary pharmaceuticals Flashcards
drugs and hormones in livestock
• animal health • animal welfare • economic return Meets the need of producing more food on less land with fewer farmers • Made intensive livestock-rearing possible
Functional Classification
of Vet Drugs and Hormones
Antibiotics to control disease and promote growth • Hormone and hormone-like substances • Beta-agonists • Topical antiseptics, bactericides, fungicides • Antiparasitic drugs: anthelmintic, coccidiostats • Ionophores to alter stomach microorganisms • Thyreostats • NSAIDS and tranquilizers
Antibiotics
-how are they used
• Therapeutically – treatment of infections • Prophylactically – to prevent disease (especially in intensive farming) • Growth promotion – increase efficiency of feed use
how are hormones used
Natural hormones or synthetic analogues • Natural hormones used to control reproductive cycle • Both used to increase feed efficiency and give leaner meat at reduced cost to producer
what are the common antibiotics used
Tetracyclines: tetracycline, chlortetracycline, oxytetracycline • Ionophores: monensin, lasalocid • Macrolides: erythromycin, tylosin, tilmicosin, tulathromycin • Penicillin and Beta-Lactams: penicillin-G, amoxicillin, ampicillin • Sulfas: sulfamethazine, sulfadiazine • Aminoglycosides: neomycin, gentamycin • Lincosamides: lincomycin, clindamycin
what are the common Hormones
used
Natural hormones: – 17β-estradiol – Testosterone – Progesterone
• Synthetic hormones: – Zeranol – Trenbolone acetate – Melengestrol acetate
• Most applied as implanted pellets
• MGA applied as a feed additive
Antimicrobial Resistance in
Microorganisms AMR
AMR occurs when a AM substance is no longer effective in killing or inhibiting the growth of a pathogenic microorganisms. • Probability of AMR increases with the length of time of exposure. • Some strains contain resistance to AM, survive and reproduce to confer resistance to further generations and possibly to other micro-organisms. • The focus is usually on resistant bacteria, therefore the term “antibiotic resistance”.
AMR: What are the Issues?
Increasing occurrence of AMR
poses a threat to our ability to fight
human and animal infections.
• Effective antibiotics become fewer
in number.
• Treatment becomes more
challenging and more expensive.
“The rise of antimicrobial resistance is a global health crisis. Medicine is losing more and
more mainstay antimicrobials as pathogens develop resistance. …With few replacement
products in the pipeline, the world is heading towards a post-antibiotic era in which
common infections will once again kill. …This will be the end of modern medicine as we
know it.”
Timeline of New Drug Development and AMR
1928: Penicillin (Fleming) • 1930’s: Sulfonamide antibiotics • 1940’s: Penicillin mass produced • 1950’s &1960’s: 2nd gen drugs (phenicols, macrolides) • 1980’s & 1990’s: fewer new drugs, most variations on older drugs • Time between introduction and development of AMR decreasing
AMR: How Does it Develop?
. Use in agri-food industries to treat specific diseases or to prevent illnesses and promote growth 2. Over-use or inappropriate use of AM in human medicine 3. Environmental contamination
What is being done to fight AMR?
The WHO suggests the following:
Policy makers can help by:
• strengthening resistance tracking and laboratory capacity
• regulating and promoting appropriate use of medicines
Policy makers and industry can help by:
• fostering innovation and research and development
• Promoting cooperation and information sharing among all
stakeholders
Health workers and pharmacists can help by:
• enhancing infection prevention and control
• only prescribing and dispensing antibiotics when truly needed
• prescribing and dispensing the right antibiotic(s) to treat the illness
Governmental Efforts to Fight AMR
The fight against AMR has become highly politicized
• There are may vested interests in industry that fight regulations
• Some attempts to collaborate with industry to “voluntarily” reduce AM
use, especially for growth promotion purposes: US FDA Guidance #213
• California just enacted (October 10) legislation to require a
veterinarian’s prescription for therapeutic antibiotic uses in livestock,
ban other uses (including low-dosage levels used to prevent diseases),
and require that data be collected on antibiotic us
e
• In Canada, Health Canada has responded by:
– strengthening surveillance systems that monitor AMR
– strengthening the responsible use of antimicrobials in human and veterinary medicine
– strengthen regulations for veterinary medicines and medicated feeds
– encourage practices that reduce use of antibiotics
DES, Hormones and
International Trade
The “Hormone Dispute” with the EU
• 1950’s to 1980’s: Diethylstilbestrol (DES) incidents >> negative public sentiment • 1988: The EU banned the use of some natural and synthetic hormones used a growth promoters and banned them from imported meats and products • The US and Canada considered this a restrictive trade practice and have fought the ban through the WTO • Internal ban lead to “black market”, alleged involvement of the “Mafia” and a murder of a veterinarian in Belgium • Natural Hormones – 17β-Estradiol – Testosterone – Progesterone • Synthetic Hormones – Zeranol – Trenbolone acetate – Melengestrol acetate
Intrinsic resistance:
Ability of microorganisms to
thrive in presence of AM due to inherent
characteristics
Acquired resistance:
Development of AMR due to
mutation and acquisition of genetic material from
other micro-organisms
