week 6 Flashcards
Over the years, what does the industry tend to do?
Compartmentalise activities
How do we adopt a more integrated thinking approach?
Understanding concentration at the active site
e.g. CNS
What is pharmacodynamics?
Both efficacy and safety
all part of the same biological continuent
Define pharmacokinetics
- The study of the effect of the body on the drug
2. medicinal chemistry
Define pharmacodyanmics
- The study of the effect of the drug on the body
2. biology - good and bad
What impacts half life that drives dose regimens?
- Volume of distribution
2. Clearance
What defines the oral bioavailibility?
- Clearance
2. Absorption for oral drugs
What are the key questions for integrated thinking?
- Can we detect?
- Are we achieving?
- Can we observe?
- Can we measure?
- Can we demonstrate
- Does all this translate to a disease response?
What is an example of the key questions for integrating thinking?
- Expression of the target and/or activity of the pathway
- Active blood or tissue concentrations
- Activity on the desired molecular target
- modulation of the desired biochemical pathway
- Achievement of the desired biological effect
- Disease response
Where do we live in?
- one-click world
- Everything is instant
- we order instantly
- get decisions instantly
What is important in biology and also designing the safety study?
- look for a patient response
2. can I get signal efficacy in a week? or is it up to 6 months of dosing?
What is the biological turnover rates of Structure or Functions?
- Electrical signals (msec)
- Neurotransmitters (msec)
- Chemical signals (min)
- Mediators, Electrolytes (min)
- Hormones (hr)
- MRNA (hr)
- Proteins/enzyme (hr)
- Cells (days)
- Tissues (months)
- Organs (year)
- Person (Century)
What does the pharmacodynamics look at?
- Biological effect over time
2. concentration vs effect - represented in a simple sigmoidal E-max response
What does pharmacokinetics look at ?
- Integration of concentration over time
What do we need to have an understanding of in terms of PK/PD study?
How the magnitude and time scale of biological effect relates to drug concentration in a biophase which is blood/plasma for convenience
What can PK/PD modelling and stimulation be used an?
- Applied science tool to provide answers on efficacy and safety of new drugs faster and at a lower cost
where can PK/PD modelling be used in?
preclinical phase through all clinical phases of drug development
What does optimal use of PK/PD modelling and stimulation lead to?
- Fewer failed compounds
- Fewer study failures
- Smaller number of studies needed for registration
How can PK/PD modelling fulfil its potential in drug development?
It needs to be embraced across the industry and regulatory agency
more education on this topic is required
What is PK/PD model?
combines two classical pharmacologic disciplines of pharmacokinetic and pharmacodynamic
- it integrates both these into one set of mathemathical expression that allows decription of time course of effect intensity in response to administration of a drug dose
when can we utilise PK/PD modelling and stimulation?
models should be developed early in programme development
during the preclinical phase
such models are continously updated and refined as more data becomes available
when can PK/PD modelling offer the greatest value?
if preclinical data can be modelled in combination with existing clinical data on related compounds
what are potential benefits of modelling in preclinical phase?
- selecting the optimal compound
- predicting clinical potency estimates (EC50)
- providing the guidance for the dose range to be tested in early clinical trials
- providing guidance for optimal sampling
- predicting oral bioavailibility
- predicting hepatic clearance
- assessing the potential for drug-drug interactions
what should PK/PD model include?
- rate-limiting component from the mechanism of action
2. e.g. receptor binding, protein synthesis
What affects a model predictivity?
- protein binding
- receptor occupancy (species difference)
- Active metabolites
- Competitive endogenous ligands
What is prediction of PK/PD?
look at human efficacy and dose based on data
What is comparison of PK/PD?
simple at in-vitro level comparing IC50 across a range of compounds
What is PK/PD?
Funneling approach
look very early on a simple IC50 in a cellular expression system
or simple whole blood system
what are the four basic attributes to characterise PK/PD models?
- link between measured concentration and the pharmacologic response mechanism that mediate observed effect, direct vs indirect response
- the response mechanism that mediates the observed effect, direct vs indirect response
- the information used to establish link between measured concentration and observed effect
- time dependency of involved pharmacodynamic parameters
e. g. time variants vs time invariant
define disposition
What happens to the drug after it enters the body, including distribution and elimination process
What is biosignal?
Any signal in human being that can be continually measured and monitored e.g. ECG
What is sensitivity analysis?
determines how different values of independent variable affect a particular dependent variable under a given sit of assumptions