break up

Question 1

adverse drug reactions

Answer 1

can be considered a form of toxicity, can be dose related, can be allergic, can be idiosyncratic.
can be severe, mild, moderate, or fatal

Question 2

what are drug residues and the importance

Answer 2

drugs given to animals can end up in food. however more likely that a microbial contamination occurs. there a residues monitoring program. NOEL
residues can be prevented if simples rules are followed

Question 3

rules to avoid residues issues

Answer 3

don’t use drug off label. identify treated animals, keep excellent tracking/history, accessible records of treatment, store drugs and chemicals correctly. if adding to feed ensure no mixing errors/

Question 4

what are cytotoxic drugs used for

Answer 4

used for the treatment of invading cells, such as pathogenic micro-organisms or invading cancer cells.

Question 5

what is selective toxicity

Answer 5

the use of chemicals indented to be toxic to a pathogenic organism, but harmless for the host.. exploits biochemical differences between the target cell and the host

Question 6

Pharmacophore

Answer 6

Microbial protein = the receptor
antimicrobial moleucule= the ligand
the active chemical moiety of the antimicrobial drug is termed the pharmacophore.

Question 7

types of selective toxicity mechanims

Answer 7

cell wall synthesis in bacteria and fungi, cell membrane synthesis, synthesis of 30s and 50s ribosomal subunits, nucleic acid metabolism, topoisomerase function, viral proteases and integrases

Question 8

the selective nature of chemotherapeutic agents means..

Answer 8

they are usually safe for the host and

associated with few adverse events

Question 9

antimicrobial drugs

Answer 9

assist the host’s defence mechanisms in containing and eliminating the invading micro-organism

Question 10

how are antimicrobial drugs classified

Answer 10

1. Class of micro-organism it kills e.g.
bacteria vs fungus
2. Antibacterial activity
3. Bacteriostatic vs. bactericidal
4. Time or concentration dependent
activity

Question 11

what is gram-negative and gram-positive

Answer 11

gram negative has a thin peptidoglycan layer and gram positive has a thick layer.

Question 12

what is a narrow spectrum and a broad spectrum

Answer 12

narrow= only kills gram negative OR gram positive
broad = kills or inhibits both

Question 13

MIC ?

MBC?

Answer 13

MIC - minimum inhibitory concentration
MBC - minimum bactericidal concentration
MIC= the lowestest concentration of an antibiotic required to prevent growth of an organism
MBC = the lowest concentration of an
antibiotic required to kill the pathogen
MBS is no more than 4x the MIC

Question 14

Time dependent and concentration dependent

Answer 14

time= lenght of time that the serum drug concentration exceeds the MIC determines killing success.
concenctration= the rate of kill increases with the drug concentration above the MIC

Question 15

Penicillin

Answer 15

is a Beta lactam antibiotic, the B lactam ring is essential for the antibacterial activity. it is bactericidal, time-dependent

Question 16

Penicillin MOA

Answer 16

bacteria have a rigid outer cell wall and high internal osmotic pressure, the peptidoglycan component of the cell wall is essential for integrity.
less effective against gram-negative
binding of penicillin binding proteins inhibits peptidoglycan synthesis

Question 17

pencillin resistance

Answer 17

the producct of beta lactamases that break the Beta lactam ring. gram -ve postive have inherent resistance, mutation in porin structure

Question 18

overcoming resistance

Answer 18

modification of the Beta-lactam nucleus to stabilise the drug in the presence of Beta lactamases. use of beta lactamase inhibitors

Question 19

intrinsic resitance mechanisms include:

Answer 19

Low affinity of the drug for the target
◦ Bacteria not permeable to the drug
◦ Efflux transporters
◦ Innate production of inactivating enzymes

Question 20

what is the mutant selection window

Answer 20

it is the window betwen MPC and MIC where the bacteria is likely to mutate making the drug ineffective.

Question 21

acquired resistance

Answer 21

occurs due to a genetic change in the bacteria, mutation or horizontal gene transfer
Transfer of bacteria between people
◦ Transfer of resistance genes between bacteria
(usually on plasmids)
◦ Transfer of resistance genes between genetic
elements within bacteria (using transposons)

Question 22

benzimidazoles

Answer 22

is a anthelmintics, inactive prodrugs, affect the metabolism of the worms by inhibiting Beta-tubulin polymerisation.
the damaged worms are expelled, up to 400x more selective for nematode tubulin.

Question 23

how does benzimidazoles get into the parasite

Answer 23

small amounts are ingested, however, majority are by transcuticular diffusion.
lipophilic drugs which aid absorption into the parasite, affected by GIT transit time, the weak base which means ionised in acidic GIT.

Question 24

benzimidazoles efficacy- host fators

Answer 24

GIT transit time
Diet type (pH, transit, uptake)
Closure of oesophageal groove intermittently in ruminants – drug bypass
Nutritional status
Liver function – rapid first pass metabolism

Question 25

BZD efficacy Tx factors

Answer 25

anthelmintic medications often fail.
◦ Compliance
◦ Inappropriate drug
selected
◦ Wrong dose
◦ Re-infection
◦ Wrong diagnosis
◦ Multi-species
infection
◦ Resistance

Question 26

result of Anthelmintic resistance

Answer 26

Becoming a major worldwide issue
Intrinsic modes a minor problem
Inherited
◦ This means populations of worms become R together, rather than individuals
Not reversible
Usually to all drugs in a
class

Question 27

Mechanisms of intrinsic resistance

Answer 27

Parasites go through different stages of a life cycle – some stages may be protected from the drug (and go on to mature)
Different species of parasites in geographical regions may have different susceptibilities
Action of parasite may differ
between hosts

Question 28

Mechanisms of true resistance

Answer 28

Loss of high affinity binding sites i.e. mutation of β-tubulin
Increased efflux of drug by parasite
◦ Increased number of pumps
Modified enzyme activity by parasites