Steps of New drug discovery & development

 1. Search for the Active Site/ Target (Biological Development Phase)

   * Identifying appropriate drug "targets," such as single genes or proteins.
   * The targets are rigorously "validated," meaning proven to be involved in the disease state.
2. Search and Optimization of Active Compound (Chemical Research Phase)
    # Identification of hit molecules (hits)
discovering or inventing compounds that can alter the disease-causing mechanism, whether a single protein or a complex pathway of proteins, to bring it back into line with normal function.
* Random screening (e.g. Cyclosporine)
* Serendipity (e.g. Methotrexate)
* Molecular modification of known drug (e.g. Cephalosporins)
* Rational drug designing (e.g. ACE Inhibitors)
* Designing of a Prodrug or Active metabolite (e.g. Levodopa)
    #Identification of lead series (leads)
      set of related molecules that share common structural features and have some variation of activity if structure    is modified
      -- Optimize Lead Compound
Compounds are altered in ways that
* increase their potential efficacy
* minimize any potential side effects
3. Testing of the Active Compound (Pre-clinical Phase)
* Pharmacological testing (screening)
* Preliminary toxicilogical testing
* Pharmacokinetic testing
* Chemical and Pharmaceutical development
4. Clinical Trials
5. Approval Process