Pharm3

Question 1

Humans and exposure to drug residues:

Answer 1

o Allergies
o Carcinogenic
o Promote antibiotic resistance

Question 2

Drug’s half-life

Answer 2

• Drug elimination rates are dependent on a drug’s half-life

* Drug’s half-life is used to determine dosage interval and withdrawal time

Question 3

Drug Effect

Answer 3

• Drugs must combine w/ cellular receptors to exert their effect
• Cellular receptors bind only specific drugs
• Drugs have an effect only on tissues that have receptors they can bind to
• The tendency of a drug to bind to a receptor and its ability to produce the desired effect can vary

Question 4

Agonist

Answer 4

• chemical that binds to a receptor and activates the receptor to produce a biological response
• affinity and efficacy “fit”- opiods

Question 5

Partial agonist

Answer 5

• drugs that bind to and activate a given receptor, but have only partial efficacy at the receptor relative to a full agonist
• buprenorphine- binds and exerts effect, but not as pronounced

Question 6

Antagonist

Answer 6

• a substance that interferes with or inhibits the physiological action of another.
• Naloxone- binds and the receptor is blocked from other opoids

Question 7

Types of cellular effects observed after drug binds to receptor

Answer 7

secretion of a substance (GnRH)
cell death (Lysodren)

Question 8

Nonreceptor

Answer 8

Mediated drug effects (i.e. drugs exert their effect w/o binding to a receptor)
*Mannitol, EDTA, Antacids

Question 9

Antimicrobials

Answer 9

• Drugs that kill or inhibit the growth of microorganisms
* action described as bactericidal, bacteriostatic, virucidal, fungicidal
• Can be administered orally, injected parenterally, or applied topically

Question 10

Antimicrobials Can be divided into two groups:

Answer 10

1. Drugs for external application

2. Drugs for internal administration

Question 11

Disinfectants and antiseptics

Answer 11

• chemical agents used to decrease microbe #’s in the environment
• meant for external application only
• spectrum of activity, environmental condition required for proper use, and individual characteristics vary between agents

Question 12

Antibiotics and antifungals

Answer 12

drugs intended for use w/in the body for systemic distribution

Question 13

Successful use of Antibiotics and antifungals requires that:

Answer 13

1. Microorganism be susceptible to antimicrobial (G+,G-)
2. Antimicrobial reach site of infection in high enough concentrations (Abscess)
3. Animal tolerate antimicrobial and its side effects (vomiting/diarrhea, nephrotoxicity)

Question 14

Antibiotic susceptibility

Answer 14

the effectiveness of an antibiotic in inhibiting the growth of bacteria is reflected in its measurable minimum inhibitory concentration (MIC)

Question 15

Antibiotic resistance

Answer 15

• bacteria’s ability to not be affected by an antibiotic
• can be the result of genetic mutations in individual bacteria that are passed on to future generations
• inappropriate administration of antibiotics can also promote resistance

Question 16

The mechanism by which an antimicrobial kills or inhibits the growth of bacteria varies

Answer 16

• some inhibit cell wall formation
• some change the permeability of the cell membrane
• some inhibit protein synthesis
• some interfere w/ metabolism
• some damage bacterial DNA or RNA

Question 17

Penicillins

Answer 17

o First widely used antibiotic
o Developed in 1940’s
o First line of defense
o Examples: procaine penicillin G, benzathine penicillin G, ampicillin, amoxicillin, cloxacillin, carbenicillin, ticarcillin

Question 18

Penicillin Mechanism of action

Answer 18

Interfere w/ formation of bacterial cell wall in actively growing bacteria

Question 19

Distribution and Elimination of penicillin

Answer 19

o Distribution– distributed well to most tissues except CNS

o Elimination– excreted mostly by the kidney in an unchanged form

Question 20

Absorption of penicillin

Answer 20

 Good after parenteral or oral administration
 Pen. G not absorbed well orally
 Give on an empty stomach, except amoxicillin

Question 21

Penicillin’s Spectrum of Activity

Answer 21

• Effective vs. most G+ bacteria
• Resistant G+ bacteria secrete β-lactamase enzyme that disrupts the structure of the penicillin molecule
• Not effective vs. most G- bacteria

Question 22

Precautions of penicllin

Answer 22

o Possible allergic reactions: fever, swollen lymph nodes, facial swelling, skin rash, shock
o Possible anorexia, vomiting, diarrhea with oral administration
o Can lead to “superinfection” in guinea pigs, hamsters, rabbits
o Do not use w/ bacteriostatic antibiotics
o Withdrawal times must be observed in food animals

Question 23

Cefpodoxime

Answer 23

(Simplicef)
• oral antibiotic
• administered SID for skin infections

Question 24

Cephalosporins

Answer 24

• Similar properties as penicillins
• Use on gram +
• Examples: cephalexin (BID), cefazolin, cefadroxil, cephapirin, ceftiofur,

Question 25

Mechanism of Action of Cephalosporins

Answer 25

Inhibit the formation of the cell wall in actively growing bacteria

Question 26

Absorption of Cephalosporins

Answer 26

- Absorbed well after parenteral or oral administration | - Absorbed more slowly in the presence of food

Question 27

Distribution, Metabolism, Elimination of Cephalosporins

Answer 27

– distributed well to all tissues except CNS | – excreted by the kidney either unchanged or after being metabolized by the liver

Question 28

Spectrum of Activity of Cephalosporins

Answer 28

* First generation: G+ bacteria * Second and third generation: G+ and some G- bacteria * Ineffective against penicillin resistant bacteria

Question 29

Precautions of Cephalosporins

Answer 29

* Possible allergic reactions: fever, swollen lymph nodes, facial swelling, skin rash, shock * May cause pain when injected IM * Oral administration may cause vomiting, diarrhea, and anorexia * Do not use w/ bacteriostatic antibiotics * Potentially toxic to kidneys if overdosed * Observe withdrawal times

Question 30

Aminoglycosides

Answer 30

* Powerful G- antibiotics * Not generally used in food animals * Examples: gentamicin, amikacin, kanmycin, neomycin, streptomycin, tobramycin

Question 31

Mechanism of action of Aminoglycosides

Answer 31

Inhibit bacterial protein synthesis by attaching to the bacterial ribosome

Question 32

Absorption of Aminoglycosides

Answer 32

* Hydrophilic at physiologic pH * Not well absorbed from the GI tract of the uterus * Absorbed well after parenteral injection

Question 33

Distribution and Elimination of Aminoglycosides

Answer 33

• Does not penetrate CNS • Tends to accumulate in the inner ear tissues and Elimination– excreted by the kidney

Question 34

Spectrum of Activity of Aminoglycosides

Answer 34

* Broad spectrum of activity: effective vs. G- and some G+ * Widely used against G- bacteria * Not effective against anaerobic bacteria