W1 - Practical Pharmacology, Antimicrobial Drugs

what is pharmacology?

study of how chemical agents (natural and synthetic drugs) affect biological systems

what are the five rights of medication administration?

right…drug, amount, time, patient, route (DA-TPR)

what is pharmacokinetics?

study of what the body does to a drug

what are the four steps of pharmacokinetics?

absorption, distribution, metabolism, excretion (ADME)

what is absorption in pharmacokinetics?

movement from site of administration to bloodstream

what is distribution in pharmacokinetics?

movement from bloodstream to tissues

what is the most (and least) bioavailable route for absorption?

IV (and enteral/oral)

how does distribution work?

drug crosses through cell membranes and matches up with receptors

what are some exceptions in terms of cell membranes that a drug can cross?

blood-brain barrier, sometimes other tissues (eye, prostate, placenta, etc)

what organs receive drugs first?

high blood flow organs (brain, heart, liver, kidneys)

what is an agonist?

a drug that causes cell reaction

what is an antagonist?

a drug that prevents cell reaction

what is metabolism also known as?

biotransformation

what is the main organ responsible for metabolism of drugs?

liver

name the 4 ways drugs can be converted

from active to inactive metabolite, from one active to another active, from inactive to active, from active to toxic

what is metabolism in pharmacokinetics?

how body uses the drug and modifies it

what is excretion in pharmacokinetics?

removal of drug and its metabolites from the body

what organ excretes most drugs?

kidneys

what is withdrawal time?

for food animals: the amount of time that must pass between the last dose of a medication being administered until drug residues are low enough to be safe for human consumption

what is T1/2?

the time it takes for the concentration to decrease by half

what does TI stand for?

therapeutic index

what is TI?

drug dosage that produces the desired affect with minimal or no signs of toxicity

what is the equation to calculate TI?

this

what does LD50 stand for?

lethal dose

what does ED50 stand for?

effective dose

question

TI = 2x effective dose to be lethal

what does a higher TI entail?

safer drug (ex: antibiotics)

what does a lower TI entail?

less safe drug (ex: anesthetics)

what is pharmacodynamics?

study of what a drug does to a body

what does the FDA regulate drug-wise?

development and sale of drugs

what does the EPA regulate drug-wise?

topical pesticides

what does the USDA regulate drug-wise?

biologics (therapeutic agents derived from living organisms)

what does the FARAD (Food Animal Residue Avoidance Databank) do drug-wise?

provides database to provide livestock producers and veterinary professionals with information on how to avoid drug residue in meat, eggs, and milk

what does the DEA regulate drug-wise?

enforces the Controlled Substances Act of 1970

what is an antimicrobial drug?

kills or inhibits the growth of microorganisms

what is an antibacterial drug?

kills or inhibits the growth of bacteria

what is an antibiotic?

antibacterial compounds produced naturally by other microorganisms

what is an antifungal?

kills or inhibits the growth of fungi

what is an antiprotozoal?

kills or inhibits the growth of protozoa

name three mechanisms of action for antibiotics

inhibiting cell wall synthesis; increasing cell membrane permeability; interfering with protein synthesis, nucleic acid metabolism, and other metabolic processes

what is a bacteriostatic drug?

antibiotic that inhibits growth and reproduction of bacteria

what is a bactericidal drug?

antibiotic that kills bacteria

how do beta-lactam antibiotics work?

inhibit enzymes involved in cell wall production

how does beta-lactamase work?

enzyme inhibits beta-lactamase antibiotics

name three notable penicillins

Penicillin-G, Ampicillin, and Amoxicillin

what does MOA stand for?

mechanism of action

what are Penicillins’ MOA?

stopping cell wall synthesis (bactericidal)

what are some side effects of Penicillins and Cephalosporins?

GI malfunction (diarrhea), hypersensitivity, and allergic reactions

what does it mean for a drug to be potentiated?

made stronger by adding another compound

how can Amoxicillin be potentiated?

adding clavulanic acid

what do Cephalosporins’ names typically start with?

“Cef” or “Ceph”

name three 1st gen Cephalosporins

cefazolin, cephalexin, and cefadroxil

name two 3rd gen Cephalsporins

cefpodoxime and ceftiofur

what organisms do 1st gen Cephalosporins target?

gram+ aerobes and beta-lactamase producing Staphylococcus

what are Cephalosporins’ MOA?

stop cell wall synthesis (bactericidal)

name three notable Aminoglycosides

Gentamicin inj, Amikacin inj, and Neomycin

what are some side effects of Aminoglycosides?

kidney toxicity (nephrotoxic) (make sure patients are hydrated before giving!), ear toxicity (ototoxic), and poor GI absorption (used parenterally)

what is the MOA of Aminoglycosides?

stop bacteria protein synthesis (bactericidal)

how does the name of Sulfonamides start?

“Sulfa”

name three notable Sulfonamides

Sulfadiazine, Sulfamethoxazole, Sulfadimethoxine

what is the MOA of Sulfonamides?

inhibit bacterial production of folic acid (bacteriostatic if not potentiated)

what are some side effects of Sulfonamides?

GI malfunction (diarrhea), dry eye, bone marrow suppression, teratogenic, hypersensitivity reactions

what can Sulfadiazine be potentiated with?

trimethoprim

what can Sulfamethoxazole be potentiated with?

trimethoprim

what can Sulfadimethoxine be potentiated with?

ormetoprim

what is the MOA of potentiated sulfonamides?

same as “regular” sulfonamides, but added compound makes potentiated sulfonamides bactericidal

what is notable about the names of Fluoroquinolones?

ends with “-floxacin”

name three notable fluoroquinolones

enrofloxacin, ciprofloxacin, orbifloxacin

what are side effects of Fluoroquinolones?

cartilage damage in young animals (<6 mo old) (don’t use in pregnant animals), blindness (in cats), seizures (in patients with history of seizures)

name a notable Amphenicol

Chloramphenicol

what is the MOA of Amphenicols?

stop bacteria protein synthesis (bacteriostatic)

what are some side effects of Amphenicols?

diarrhea, bone marrow suppression (wear gloves when handling) (illegal in food animals)

name three Macrolides

erythromycin, azithromycin, tylosin

what is the MOA of Macrolides?

stop bacteria protein synthesis (bacteriostatic)

what are the side effects of Macrolides?

GI upset (diarrhea, which may be fatal in foals)

name a notable Lincosamide

Clindamycin

do Lincosamides target aerobes or anaerobes?

obligate anaerobes

what are Lincosamides used for?

dental disease and cat abscesses

what is notable about the names of Tetracyclines?

ends in “-cycline”

name three notable Tetracyclines

tetracycline, oxytetracycline, doxycycline

what are notable side effects of Tetracyclines?

diarrhea, esophageal strictures in cats, yellow discoloration of enamel

name a notable Nitroimidazole

Metronidazole

name some side effects of Nitroimidazoles

dose related neurotoxicity (tremors, seizures) (illegal in food animals)

name five notable anti-fungal drugs

Amphotericin B, ketoconazole, fluconazole, itraconazole, miconazole

what fungi do anti-fungal drugs typically treat?

systemic fungal infections, yeast infections, and dermatophytes

name five notable species involved in systemic fungal infections

Histoplasma, Blastomyces, Cryptococcus, Coccidioides, Aspergillus

name two notable species involved in yeast infections

Candida and Malassezia

name two notable Dermatophytes species

Microsporum and Trichophyton

name a side effect of Amphotericin B

hepatotoxic (liver toxicity)

name a side effect of the “-conazoles”

nephrotoxic (kidney toxicity)

what do 3rd gen cephalosporins target?

gram negative bacteria

the clavulanic acid in Clavamox makes amoxicillin stronger by:

preventing breakdown by beta-lactamase producing bacteria

name five mechanisms in which antibiotics eliminate and destroy bacteria

inhibition of cell wall synthesis, damage to cell membrane, inhibition of protein synthesis, interference of metabolism, and impairment of nucleic acids