clinical trials
TRANSCRIPT
Overview
• History • Definition • Regulatory bodies• In silico and in vitro trials• Pre clinical trials• Phases of clinical trials • Types of clinical trials
History
• James Lind, Scottish physician• First ever clinical trial• Group of sailors – suffering
from Scurvy• Vinegar to cider• Citrus fruits• Discovered Vitamin C can cure scurvy
Definition
• Clinical trials mean a systematic study of a new drug ( therapy protocols, devices ) in human subjects to generate data for discovering or verifying the clinical claims or pharmacological and adverse effects with an aim to determine the safety and efficacy of drugs in question
Regulatory bodies
• U.S.A – Food and drug administration• U.K – Committee on safety of medicine• Japan – Ministry of health labor and welfare• India – Drugs controller general, Govt.of India
FDA 1906 – Interstate transport of adulterated
food and drugs 1938 – Elixir sulfanilamide 1960 – Thalidomide
Safety
Efficacy
In silico
• Simulator software available• Predict mechanism, metabolism, distribution• Expected to contribute in reduction of animal
use• Disadvantage: applicable only to those areas
which are well understood. Also hepatotoxicity neurotoxicity can not be predicted
In vitro
• Isolated cells, tissues and organs• The National disease research institute- 130
types of tissues for >50 types of disease• E.g.: monoclonal antibodies – cultured cells• Limitation: not available for all the tissues
Normal systemic pharmacokinetic profile (ADME) is absent.
PRE CLINICAL Non human• - Lab• - Animal (rats, rabbits, etc.) Pharmacological studies: to know Biological activity Mechanism of action Selectivity and specificity Drug metabolism
• Toxicity – Acute toxicity Sub acute toxicity Chronic toxicity Including effects on
reproduction, teratogenicity,
carcinogenicity and mutagenicity.
PHASES Phase 0: Pharmacodynamic (PD) and
pharmacokinetics (PK) Phase 1: Screening for safety Phase 2: Efficacy of the drug Phase 3: Final confirmation of safety and
efficacy Phase 4: Post marketing surveillance Phase 5: Translational research
Thalidomidetests in pregnant mice, rats, and
guinea pigs were negative.
Cerivastatinsubstantial risk for
severe or fatal rhabdomyolysis.
16
FenclofenacNo animal toxicity in 10 species. Severe
liver toxicity in humans
CisaprideHeart rhythm disturbances in trials, but not in animal studies
5 2
34
TroglitazoneSafe in rats, severe
liver failure in humans.
PhenylbutazoneBone marrow toxicity, phototox & liver tox
only in humans
PenicillinDiscovered in 1929
Not used till 1939 because of its ineffectiveness in curing infected rabbits
Furosemide
Experiments in mice: extensive liver damage
Aspirin
Causes teratogenic malformation in mice, rats, dogs, cats, rabbits and monkeys
Phase 0 or microdose
• Microdosing :• Less than 1/100th of the dose calculated to
yield a pharmacological effect of the test substance based on primary pharmacodynamic data obtained from in vitro and in vivo (typically doses in or below the low microgram range) and at a maximum dose of <100microgram
Objectives of microdosing study To clarify bioavailability and PK profiles To clarify metabolic profiles To obtain information on tissue distribution
18
Basic features First-in-human trial conducted prior to
traditional Phase 1 study Small number of subjects (≈10-15) Limited drug exposure Low, non-toxic doses (<100mcg) Short duration (≈ ≤7 days) No therapeutic intent Eliminate bad agents early (rapid clearance,
poor bioavailability, fails to reach target)
Microdosing trials are not definitive studies
Drug candidates (NME/NCEs)
AnimalmodelsIn-vitroIn-silico
Limited toxicology studies
Human microdose study(Phase 0)
PROCEDURE
• Plasma / urine / biopsy sample serially collected
• Sample analyzed for parent drug and metabolite
• Microdose -> micro plasma drug concentration• Extremely sensitive analytical methods
required
21
POSITRON EMISSION TOMOGRAPHY (PET)
Drug specific receptor ligand labeled with a short lived positron emitting isotope
Distribution of drug and relative concentration at target area over time can be visualized
Info: mostly PD data through real time imaging and limited PK data
Liquid chromatography mass spectrometry
Generate drug concentration data from samples(plasma/ urine) overtime.
Accelerator mass spectrometry AMS works on isotope ratio
method Measures total 14C content As well as 14 C content ratio
of parent drug to metabolite after separation by HPLC
Info: Extent of metabolism measure of first pass effect
10.0
Oral microdose (100 ug)
1.0
0.1 0 1 2 3 4 5 6 7 8 9
Time (h)
ng/m
L pe
r 1 m
g do
semidazolam
Oral 7.5 mg dose midazolam
Parameter Oral dose
t½ 4.0 3.0%F 22 23
0.1 mg 7.5 mg
PK prediction
34 82% were scalableOrally
administered drugs 11 100% were
scalableIV administereddrugs
LITERATURE REVIEWThere are 45 drugs with data (in peered reviewed literature ) comparing microdose PK to therapeutic dose PK
PHASE 1
Volunteers ( healthy and unhealthy) (10-100) Safety , tolerance Types• - Single ascending dose studies• - Multiple ascending dose studies• - Food effect assessments
Single ascending dose studies (SAD)
• SAD those in which small groups (3) of subjects are
given a single dose of the drug while they are
observed and tested for a period of time.
• If no adverse effects, dose is escalated with 3 new
healthy subjects
• If toxicity is observed then 3 more subjects are
given the same dose and if found toxic, the previous
dose is considered as max. tolerated dose (MTD).
Multiple ascending dose (MAD)• MAD are conducted to understand the
pharmacokinetics and pharmacodynamics of
multiple doses of the drug.
• A group of patients receives multiple low doses of
the drug
• Samples (of blood, and other fluids) are collected at
various time points
How the drug is processed within the body- analyzed
Food effect studies
• Volunteers are given 2 identical doses of the drug
on different occasion, one while fasting and
another after being fed
PHASE 2 First time in patients with target disease 100-300 subjects Phase 2A (IIA)• - Assess dosing requirements Phase 2B (IIB)• - Study efficacy Study design – case series, RCT
PHASE 3 Compare new treatments with the best
currently available treatment - Confirms its effectiveness - Monitor side effects Randomized controlled multicenter
trials Drug licensing studies (pre-marketing phase) Large study groups (300-3000 subjects)
• Phase IIIA- conducted prior to regulatory
submission of a new drug application.
• Phase IIIB- after submission, but before approval
the new drug.
PHASE 4
Post marketing surveillance Safety surveillance Rare or long term adverse effects over a
much larger patient population Harmful effects discovered by phase IV
trials may result in a drug being no longer sold, or restricted to certain rules.
• E.g.: Rofecoxib
Phase 5
• Used to signify the integration of a new clinical treatment into widespread public health• It is a survey without administration of drug
• Focus is to determine whether or not the therapeutic effect is realized in day to day
clinicalpractice
• To seek additional marketing claims for-new formulation-new indication-new combination
Some example• Phenytoin sodium / lactose• Phenytoin uses• Methyldopa + diuretic combination
Basic features
• No dosing• No patient monitoring• Main focus – new therapy• All reported use• Research on data collected
Phases Dosing Number of subjects
Main goal
0 Sub therapeutic
About 10 PK and PD
IA/IB/IC Ascending dose
20-100 Safety
IIA/IIB Therapeutic dose
100-300 Efficacy
IIIA/IIIB Therapeutic dose
300-3000 Therapeutic use
IV Therapeutic dose
Anyone seeking treatment
Long term effect
V No dosing All reported use
Research on data collected
• Treatment Trials- test experimental treatments, new combinations of drugs, or new approaches to surgery or radiology/radiation therapy.
• Prevention Trials- look for better ways to prevent disease in people who have never had them or prevent them from returning.
• Diagnostic Trials- conducted to find better tests or procedures for diagnosing a particular disease or condition.
• Screening Trials- test the best way to detect certain diseases or health conditions.
• Quality of Life- explore ways to improve comfort and the quality of life for individuals with chronic illness