Pharma - Principles Flashcards
What is the difference between pharmacology and therapeutics?
→ pharmacology is more focused on the drugs
→ therapeutics is more focused on the patient
What is pharmacodynamics?
what the drugs do to the body
What is pharmacokinetics?
what the body does to the drugs
What are the 3 main questions one should ask themselves when considering how a drug exerts its effects on the body?
→ Where is this effect produced?
→ What is the target for the drug?
→ What is the response that is produced after interaction with this target?
Where is the effect of cocaine felt in the body?
euphoric feeling is felt in the dopaminergic neurones in the nucleus accumbens in the brain
What is the target for cocaine?
dopamine reuptake protein on the pre-synaptic terminal
What is the response that is produced after cocaine interacts with its target?
cocaine blocks the reuptake of dopamine from the synapse
more dopamine is available to bind to the the D1 receptors
activation of this receptors is what causes the euphoria
What the 4 different classes of drug targets?
→ Receptors
→ Enzymes
→ Ion channels
→ Transport proteins
What is the drug target of Aspirin?
enzyme
What is the drug target of local anaesthesia?
ion channel
What is the drug target of prozac (SSRI)?
transport protein
What is the drug target of nicotine?
receptor
What do drugs need to be effective therapeutically?
→ high selectivity for a particular drug target
→ drug dosage
Why was drug dosage important for Pergolide (drug for the treatment of Parkinson’s disease)?
→ at lower doses it targets the dopamine D2 receptor and produces an anti-parkinsonian effect
→ at higher doses it can target the serotonin and adrenergic receptors, causing hallucinations + hypotension, respectively
What are 4 ways in which drugs can interact with the receptors?
→ Electrostatic interactions
- this is the most common mechanism and includes hydrogen bonds and Van der Waals forces.
→ Hydrophobic interactions
- this is important for lipid soluble drugs.
→ Covalent bonds
- these are the least common as the interactions tend to be irreversible
→ Stereospecific interactions
- a great many drugs exist as stereoisomers and interact stereospecifically with receptors.
What are the 2 ways of classifying drug interactions with receptors?
→ agonist
→ antagonist
What is an agonist?
can bind + activate the receptor
What is an antagonist?
can bind to receptor but blocks the activation of said receptor
What is the affinity of a drug?
determines strength of binding of the drug to receptor
What is the efficacy of a drug?
ability of an individual drug molecule to produce an effect once bound to a receptor
What does high affinity of drug result in?
stronger drug-receptor complexes are formed
What the three different classes of drugs based on differences in efficacy?
→ antagonist = blocks receptor but has no actual effect
→ partial agonist = can only illicit a partial response from the receptor
→ full agonist = has maximum efficacy, illicits maximum response from the receptor
What is the potency of a drug? (general definition)
concentration or dose required to produce a defined effect
What is the standard measure of potency of a drug?
determine the conc. or dose of a drug required to produce a 50% tissue response
What is EC50?
the nomenclature for half maximal effective concentration
What is ED50?
the nomenclature for half maximal effective dose
What effects whether a drug can reach a relevant target at sufficient concentrations or not?
pharmacokinetics factors
List 4 major pharmacokinetic factors or phases.
→ Absorption
→ Distribution
→ Metabolism
→ Excretion
What is meant by absorption in pharmacokinetics?
→ passage of a drug from the site of administration into the plasma
→ process for drug transfer into the systemic circulation
What other concept is relevant to absorption in pharmacokinetics?
Bioavailability
What is meant by bioavailability in pharmacokinetics?
→ fraction of the initial dose that gains access to the systemic circulation
→ outcome of drug transfer into the systemic circulation
What is a huge determinant of bioavailability and absorption?
site of administration
What are the 2 ways in which drugs can move around the body from the site of initial administration?
→ bulk flow transfer (e.g. blood stream)
→ diffusional transfer (e.g. molecule by molecule over short distances)
What mode of drug transfer is going to have 100% bioavailability?
→ bulk flow transfer
→ e.g. IV fluids straight into the circulation
Why are other ways of administering drugs unlikely to have 100% bioavailability?
the rest are diffusional transfer, needs to cross at leats one lipid membrane to reach systemic circulation
What are some other forms of drug administration besides IV?
Oral
Inhalation
Dermal (percutaneous)
Intra-nasal
What are the 4 different mechanisms by which chemicals can diffuse across the plasma membrane?
Simple diffusion (across lipid bilayer)
Diffusion across aqueous pores
Carrier mediated transport
Pinocytosis