Pharmacology & Drugs Flashcards
What is it thought paracetamol inhibits the release of?
COX-3
What are the 2 route by which paracetamol is broken down?
98% - Glucuronic & sulphuric acids
2% P450 enzymes
What is the toxic substance produced by the P450 enzymatic breakdown of paracetamol?
NAPQ1
What is NAPQ1 deactivated by?
Glutathione
What is the maxium dose of paracetamol for an average adult in 24hours?
4g.
What is the half life of paracetamol?
2-4 hours in a health individual
What is the half life of a drug?
the time taken for drug plasma concentrations to half
In linear Pharmacokinetics how many half lives does it take to clear a drug?
4-5
What does Pharmacokinetics involve?
Administration
Distribution
Metabolism
Excretion
Whats the biggest difference between enteral and parental administration?
Parental by-passes liver metabolism
What is the bio-availability of a drug?
The percentage of the drug that enters systemic circulation
What is volume of distribution?
The apparent volume of drug in a given amount of plasma. The drug dose must first be known. - “If i give this much, how much will be in blood plasma of a given volume”
What is drug clearance?
The theoretical amount of drug eliminated from plasma/ unit time
What are the THREE mechanism by which bacteria use to be resistant to antibiotics?
Mutation of target site
Inactivating enzymes - Beta Lactase
Limiting access - increased reflux of the antibiotic
What are the THREE main ways antibiotics are used?
Guided therapy
Empircal Therapy
Prophylactic therapy
What kind of antibiotics are used in guided therapy?
narrow spectrum
What kind of antibiotics are used in empirical therapy?
Broad spectrum
What are ideal characteristics are wanted in antibiotics?
Highly toxic to bacteria
Able to easily access the required area in the body
Able to neutralise the toxins of the bacteria
Easily Administered
Limited co-lateral damage to the patient
Limited damage to comensal bacteria
What are the Four main target areas of antibiotics?
Peptoglycan wall - Penicillin, glycopepitides
DNA - quinolones
Ribosomes - Macrolides, Aminoglycosides
Metabolism - Trimethoprim
How do Beta lactams works?
The structure of the Beta lactam is almost identical to the final structure of the peptoglycan wall synthesis - called the transpepidase protein - thus inhibiting cross linking of the peptides
What resistance is present to beta lactams?
Mutations in penicilin binding protein
Change in porins allowing access to the bacteria
Productions of beta lactamases
What can be given in combination with penicillin to inhibit beta lactamases?
Beta lactamases inhibitors - co-amoxiclav
Example of a glycopeitides?
Vancomyocin
What is vancomyocin used to treat and what can’t it treat and why?
MRSA.
it can’t treat gram-negative because it can’t cross cell membranes
What are common/ dangerous sides of Beta Lactams?
Type I hypersensitivity reactions Type IV - this is dangerous and delayed Diarrhea Liver dysfunction Secondary infection - C.Diff, Thrush
What are macrolides useful for?
They are good at entering cell, therefore if there is a bacterial infection intraceullular infection they are useful. Used alot in upper respiratory infections
What is used to break down Macrolides?
CYP 3A4
What do Aminoglycosides inhibit?
30S ribosomes, inhibiting protein synthesis
Abatacept function?
Blocks T cell activation
Tocilizumab function?
Blockage of IL-6
What is the loading dose?
The initial dose giving to bring the concentration up the therapeutic dose
What is the loading dose calculation?
Volume of distribution x target concentration
What is the maintenance dose?
The dosing to keep the wanted concentration constant
what is the maintenance dose calculation?
Clearance rate x target dose
If a drug has a low volume of distribution, will more or less drug be needed and why?
less - because more remains in the plasma as opposed to other compartments
What is Emax?
It is the maximum efficacy of the drug - its maximum stimulus.
we presume the receptors are fully saturated here.
What is E50? and how does it relate to potency?
The concentration that the drug is at when it reaches half its maximum efficacy (Emax).
the lower the E50 the more potent the drug as it reaches a the stimulus at lower concentrations
Give an example of a bacterial-static antibiotic.
Clarithromyocin
What antibiotic would cause the adverse effect of red man syndrome?
Vancomyocin
What are the two beta lactamase inhibitors that be co-given with antibiotics?
Clavulanic acid
Tazobactam
Name a reversible Nicotine receptor antagonist
Atracurium
