Type of studies

Observation

Timing of study

Pharmacodynamic studies

• Amount of drug required for optimal activity in animal model
• To estimate how much drug would be required for human use

Herbal Drug Discovery

Pharmacokinetic studies

• Pharmacokinetic data (adsorption, distribution, metabolism, excretion (ADME))
• Important values of the concentration curves include as below:

1. i.Maximum plasma concentration of the drug (Cmax)
2. ii.Time taken to achieve Cmax (Tmax)
3. iii.T1/2: half-life of the drug or the time taken for the drug to be reduced to 50% of its starting concentration
4. iv.Area under the curve (AUC)

Prior to first administration in human (Preclinical testing)

Safety pharmacology

• To establish the No Adverse Effect Level (NOAEL) value.

Effect on core system of the body: Central Nervous System, Respiratory System, Cardiovascular System.

Prior to first administration in humans (Preclinical testing):

Conducted on core system of the body

Any follow-up or supplemental studies identified as appropriate, based on a cause for concern

During Clinical Development: Additional studies may be warranted to clarify observed or suspected adverse effects in animals and humans

Before clinical trial and product registration:

Supplemental studies (if warranted)

Toxicokinetic studies

The study is conducted to quantify exposure of:

• plasma (serum or blood) concentrations, or
• the AUCs of parent compound and/or metabolite(s), or 

Single-dose toxicity studies:

Early phase of development
14 days duration or longer

Repeated-dose toxicity studies:

• tissue concentrations, or
• the exposure and dose-dependence in humans at therapeutic dose levels (either expected or established), or
•   species differences (either qualitative or quantitative)

Related to the duration, therapeutic indication and scope of propose clinical trial

Genotoxicity studies:

In vitro (Preclinical testing)

In vivo (During clinical trials)

Reproductive studies:

Before phase III

Carcinogenicity studies:

Case- by- case

General toxicity studies

These studies are conducted to obtain values as below:

• LD₅₀: dose at which half of animals treated with a single dose of test compound die
• NOAEL (no-observed adverse effect level): highest dose at which treatment related findings occur but that are not considered to be adverse
• NOEL (no-observed effect level): highest dose at which no treatment related findings occur
• MTD (maximum tolerated dose): highest dose tolerated by test animals

During Preclinical testing

Single-dose toxicity studies

The study is conducted in two mammalian species using both clinical and parenteral route of administration, with the objective to determine the mode of death and a quantitative evaluation of the approximate lethal dose.

Prior to first administration in humans (Preclinical testing)

Repeated-dose toxicity studies

The study is conducted in two mammalian species (one non-rodent) to obtain toxicity profile:

• MTD
• NOAEL

Prior to first administration in humans (2 Weeks)

During clinical development

Before phase II: 2W – 6M

Before phase III: 1M - chronic

Genotoxicity studies

• Assessment of mutagenicity in a bacterial reverse gene mutation test.
• Evaluated in mammalian cells in vitro and/or in vivo

Prior to first administration in humans ( Genotoxicity in vitro)

During Clinical Development (Genotoxicity in vivo)

Carcinogenicity studies

• To identify a tumorigenic potential in animal

Expected clinical use is continous for at least 6 months
For pharmaceuticals used frequently in an intermittent manner in the treatment of chronic or recurrent conditions

• To assess the relevant risk in humans

Reproduction toxicity studies

The data should be obtained are as below:

• Preliminary embryo- foetal study data:

-        Foetal survival

-        Body weight

-        External and visceral examination

• Fertility studies
• Precautions on prevention of pregnancy
• Pre-postnatal development study

Prior to phase III

Local tolerance studies

The data should be obtained are as below:

• Clinical signs
• Macroscopic and microscopic examination of application site

According to site/s in clinical use

Immunotoxicity studies

Case-by-case

Case-by-case

Photosafety testing

Case-by-case

Case-by-case