NMP exam sample questions Flashcards
Factors that affect absorption
- physico-chemical properties of drug
- drug formulation
- route of administration
what does ADME mean?
Absorption
Distribution
Metabolism
Excretion
Route of administration that will produce an enteral effect
Rectal
What is Bioavailability
The fraction of the dose which proceeds unaltered from the site of administration to the systemic circulation
Factors affecting bioavailability
- Poorly water soluble/slowly absorbed drug
- Malabsorption syndrome / GI surgery
- Increased gastric emptying time
- Complex formed e.g. tetracyclines and milk
- First pass effect
what is volume distribution?
pharmacokinetic parameter that represents the degree how a drug is distributed either remains in the plasma or redistribute to other tissues
It is the process of the body breaking down and converting medication into active chemical substances
Drug Metabolism
how many phase of metabolism is involved?
2 phases
What is phase 1 metabolism
- oxidation
- hydrolysis
- uses cytochome p450
- drug metabolite can still be chemically active
What is phase 2 metabolism
- conjugation
- attachment of an ionised group to the drug
- reduces drug effect
makes metabolite more water soluble for excretion
Factors affecting drug metabolism
- Enzyme induction
- Enzyme inhibition
- genetic deficiency
- age
- liver disease
What the drug does to the body
Pharmacodynamics
Examples of neurotransmitters
- Acetylcholine (ACh)
- Histamine (H)
- Dopamine (DA)
- Noradrenaline (NA)
- Adrenaline (Adr)
- 5-Hydroxytriptamine (5-HT) [serotonin]
Factors affecting drug excretion
- blood flow to kidney (normal 1500ml/min)
- glomerular filtration rate (normal 100mls/min)
- active secretion of drugs into the kidney tubule (e.g. penicillin)
- passive reabsorption back into the tubule
is an important consideration influencing distribution
Protein binding
Will plasma protein binding increase or decrease the volume of distribution?
decrease
what is half life
Half-life is the time taken for the concentration of drug in blood to fall by half
A patient showing toxic side effects of a drug has her plasma drug concentration measured. It is 100mg/L. The normal range is 20-30mg/L. If the half life is 24 hours how long before the level drops back to within the normal range?
Computation: 100mg half in 24hours
(First half life) 50mg = 24hours
(Second half life) 25mg = 48hours (normal range 20 to 30mg)
Answer:
2 days:
o After 24 hours the level will be 50mg/L
o After 48 hours the level will be 25mg/L
Recommend omit drug for 2 days, then re-start using lower dose.
is the amount of a medication between the quantity that gives the effective dose and the amount that gives more adverse than desired effects
Therapeutic window
The ability of a drug to produce an effect
Drug efficacy
Loss of response to a drug usually due to a decrease in number of receptors
Desensitisation
give 3 examples of narrow therapeutic index drugs
lithium
gentamycin
theophylline
digoxin
phenytoin
warfarin
The term for a drug that blocks the effects of a neurotransmitter at (or near) the receptor sites
Antagonist
Condition that may follow after repeated exposure to a drug in so that the effect produced by the original dose no longer occurs i.e. increasing doses required to achieve the same effect
Drug tolerance
what is does Peak level mean
the level of the drug in the patients body is at the highest
What is trough level
the lowest level of the drug in the patients body
Why do we need to assess drug plasma concentration levels
to determine dosing intervals, or how much time should pass between each new administration of the drug.
True/False
an agonist can bind reversibly to a competitive antagonist to block its action?
False
Antagonist blocks the action of the agonist
True/False
Ibuprofen inhibits enzymes
True
Ibuprofen inhibits the cyclooxygenase family of enzymes
True/False
plasma protein binding can delay excretion of drugs
True
Drugs binding in the protein will be held in the plasma and is not available for metabolism or excretion
Antagonist blocks the response to?
Agonist
An agonist bind to receptors to cause?
a biological response
is an active metabolite that when given to a person, does not have biological activity
Pro drug
They are naturally occurring chemicals in the body
agonist
chemicals that blocks responses to neurotransmitters
antagonist
chemical alteration of the drugs in the body
metabolism
What is potentiation
A drug interaction in which the addition of a second drug intensifies certain properties of the first drug administered.
controlled drug prescriptions are valid for how many days?
28 days
The primary legislation on the UK that came fully effect in 1973
Misuse of Drugs Act of 1971
How many months should clinical management plans be updated
6 months
a drug with the ability to bind to the receptor but do not initiate a change in cellular function
Antagonist
a drug with an affinity for a receptor resulting in stimulation of the receptor’s functional properties
Agonist
What are the 3 types of adrenaline receptors and their actions
“ß1 receptors - mainly on heart (Drugs that bind to beta receptors in the heart and increase the force of myocardial contraction)
ß2 receptors - mainly on bronchioles
Alpha receptors - mainly on blood vessels (to increase blood pressure)”
When a drug no longer has an effect as the dose increases
Ceiling effect
What is the difference between sympathetic and parasympathetic nervous system
“Sympathetic (adrenergic) releases Norepinephrine binds to adrenergic receptors: Stimulated by noradrenaline, “Fight or flight”, Have alpha and beta agonists
o Alpha contracts smooth muscle, dilates pupils
o Beta increases heart rate, opens airways
Parasympathetic (cholinergic) releases Acetylcholine (Ach): Stimulated by acetylcholine and binds to muscarinic receptors.
“Rest and digest”
o Contracts iris, Decreases heart rate, Increases gut activity”
This binds irreversibly to the receptor (or may be a different site) - high concentrations of agonist cannot completely overcome antagonism and maximal response cannot be obtained
Non-competitive antagonist
A patient has started taking herbal medications what will you consider?
- potential for allergic reactions
- some are toxic if used improperly or at high doses
- They may be dangerous in combination with other substances or drugs that have been prescribed adverse reactions related to the herbal medicines
- They may mask symptoms
- They may aggravate the patients current problem
What is First Pass effect?
the Metabolism of a drug before it enters the systemic circulation. The process of first pass metabolism occurs in the gut or in the liver and can only affect the oral route. The drug is absorbed from the GI tract and passes via the portal vein (portal circulation) into the liver where some of the drug undergo extensive biotransformation. This would mean that only a proportion of the drug reaches the circulation (decrease drug concentration).