Clinical trials Flashcards
What is a clinical trial?
Any research study that prospectively assigns human participants or groups of humans to one or more health related interventions to evaluate the effects on health outcmes.
What happens during phase I of the trial?
- Test drug on a small number (10-30) of healthy volunteers
- Determine whether the drug is safe for use, observe general side effects
- Determine maximum tolerable dose
- Observe pharmacodynamics and pharmacokinetics
In what cases is the phase I trial not done on healthy patients?
Cancer drugs, because they’re toxic
What happens during phase IIa?
- 20-100 patients recruited
- Patients have to have a pure from of the disease
- Focus on dosing range, efficacy and pharmacodynamic effects in patients
What happens during phase IIb?
- 20-100 patients recruited
- Patients have to have a pure from of the disease
- Focus on dose-response relationship, drug-drug interactions (they allow non-pure form of the disease for this)
- Find out minimum effective dose and maximum tolerated dose
What happens during phase III?
- Thousands of people recruited
- Everyone with the disease who may also be on other medications
- Randomized, placebo controlled trials
- Focus on efficacy, complete safety profile, basis of regulatory information for labeling, assessment of risk/benefits
How many pivotal studies are required to approve a new drug?
2
Which phase of the clinical trial is considered for pivotal studies?
- Phase III for most drugs
- Phase II for drugs needed to treat life threatening or severely debilitating illnesses
What happens during phase IV?
- Check for toxicity from chronic exposure
- Check for idiosyncratic drug reactions
- Explore new indications for the drug
- Investigate effect on special population not covered before the NDA
What is the highest quality of evidence in a study?
Randomised controlled trials
What is the highest level of evidence in a study?
Randomized controlled trials
What is the difference between observational and experimental studies?
In an observational study, the exposures are self selected whereas in an experimental study, the exposure is allocated
What happens during a case control study?
They select people with the disease, and observe the exposures to see what led to the disease
What happens during a cohort study?
They select the exposures people had, and they observe the disease they had that may have led to the exposure
What happens during a randomized controlled trial?
Exposure is allocated to the participants, and the outcome is then observed
What are the benefits of a case control study?
- Efficient because you avoid the period of waiting for the effect
- Can study multiple risk factors at once
What are the limitations of a case control study?
The exposure times may be different, which can lead to inaccurate results and bias
What are the benefits of a cohort study?
- Can establish a temporal relationship
- Accurate exposure
- Can study multiple outcomes
What are the limitations of a cohort study?
- Hard to do
- Loss to follow-up
- Effects may vary due to other reasons like family history, co-morbidities, so there may be some bias
What are the benefits of a randomized controlled trial?
- Control over the exposure
- Minimize confounding and bias
3.
What are the limitations of a randomized controlled trial?
- Ethical issues
- Expensive
- May not get enough patients
- Patients may not comply with the treatment given
- Loss-to-follow-up
What happens during a cross-over trial?
drug one—> washout period—-> drug 2
What is the purpose of the factorial design for RCTs?
- Evaluate 2 or more interventions separately and in combination
What intervention do the control groups get?
- Standard practice
- Other treatments
- Other doses of the same treatment
- Placebo
- No intervention
