Pharmacology: Partie 3, Recherche et développement des médicaments Flashcards
Partie 3, Recherche et développement des médicaments
What are the aspects of the pre-clinical development of a drug? (3 main aspects)
- Identification de molécules candidates
- Études in vitro: cellules et animaux
- Études de toxicité aiguë et chronique
Who are études de toxicité aiguë et chronique done on?
Testing medication on at least 2 species of animals of both sexes
What are the aspects of the “étude de toxicité aiguë”?
One administration, first study realized- Étude qualitative: signes toxiques
Étude quantitative: détermination de la dose létale
What is the “dose maximale non létale”?
Highest dose without a toxic effect
What is the “DL50”?
The dose that kills 50% of the test animals after 7 days (very useful for overdoses)
What are the aspects of the “étude de toxicité chronique”?
Effects after repeated administration of the substance
Length of exposition proportional to that expected to be prescribed in humans
Determining the “dose maximale sans effet toxique en prises répétées”
Same method of administration as to be prescribed
Study effets on reproduction
- Impact of medication on fertility - Administer medication a couple weeks before mating and look for latent effects on next generation
Study effects on mutagenesis and carcinogenesis
- Genetic alterations realized in animals and cells, test to see if the medication leads to increased tumour formation and if so… by which mechanisms
Study effects on pharmacokinetics
- Absorption, distribution, metabolism, and elimination
What is tératogénicité?
Capacité de ces médicaments à provoquer de malformations foetales, anomalie des membres (ex: Thalidomide)
What are the 4 stages of development of a medication?
IN HUMANS
- Stage 1: trials on healthy volunteers to see the safety/security of the medication
- Stage 2: trials on small groups of sick individuals
- Stage 3: multi-centric trials
- Stage 4: market testing and followup
What does phase 1 test?
Evolution of the molecule being tested in the human body (cinétique) and the short term toxicity in humans (toxicité)
What are the objectives of phase 1? (5)
- Security of the medication
- Determine tolerated doses (start small… work way up)
- Determine optimal dose
- Determine pharmacokinetic characteristics
- Identify principal metabolites (molecule that has been transformed by enzymes, produced by chemical rxn)
What are the pharmacokinetic characteristics?
Bioavailability, Cmax, Tmax, ASC, T1/2, taux sériques
What is bioavailability?
The relative quantity of active ingredient absorbed that attains systemic circulation expressed in % or fraction from 0-1
- -> IV meds: 100% or 1.. directly into bloodstream
- -> per os meds —> between 0 and 1 (ex: Vancomycine affects the intestines directly and isn’t absorbed into blood therefore has a bioavailability of 0)
What is the Cmax?
Highest plasmatic concentration of medication after its administration
What is the Tmax?
Time where Cmax is reached
What is the ASC (aire sous la courbe)?
expression of plasmatic concentration as a function of time
average plasmatic concentration over duration of time
What is the T1/2 (half-life)?
Time to eliminate 50% of active ingredient from the organism
meds are usually completely eliminated after 5-7 half-lives
Who are the test subjects of phase 1?
20-50 HEALTHY individuals
What is the difference between phase 1a vs 1b?
- 1a: determine safety of medication
- 1b: determine safety and effectiveness of medication
What is the clinical surveillance in phase 1 looking for?
Biochemistry and undesirable effects
What else is evaluated during phase 1? (3)
- Pharmacological effects
- Number of daily doses
- Influence of food on medication
- Foods that slow absorption
- Little or few clinical consequences
- Meds to be taken without food
- Meds to be taken with food
- Foods that slow absorption
What are the objectives of phase 2? (4)
- Establish dose-effect relation
- Determine pharmacokinetic characteristics in actual patients
- Define optimal conditions to take the medication (dose, interval, length of time)
- Establish its safety and tolerability and find out more undesirable side effects
What are biomarkers? (DOSE-EFFECT)
Measurable biological characteristic tied to normal or abnormal processes or the action of a medication
A quantitative measure that allows you to objectify a biological response
What are biomarkers useful for? (DOSE-EFFECT)
Dépistage, réponse à un traitement, rechute, toxicité
Who are the test subjects of phase 2?
Volunteers with the illness BUT patients selected to limit the variability of the response (group as homogeneous as possible)
What is the methodology for phase 2? (4)
Studies on small groups
Studies on bigger groups to determine optimal dose/interval
Comparing multiple doses (3-10 ish)
Determine the “critères d’efficacité”
What are the objectives of phase 3? (3)
- Demonstrate effectiveness and harmlessness (innocuité) of medication in planned clinical conditions
- Prolonged administration of the medication
- Needs to find a significant difference compared to other treatments (p<0.05) according to significant endpoints