Drug Discovery Process BIT 120

ACE Inhibitors Angiotensin Converting Enzyme (ACE) causes constriction of blood vessels by converting angiotensin from inactive to active form – want to block this enzyme, so blood vessels relax (Better blood flow, lower b.p.) Look for inhibitors to other ACE proteins Class of drugs – end in “pril” – Captopril, etc.

Discovery Process Pre-Clinical Search Public Genome Databases for similar (homologous) sequences to original ACE gene Take these snippets and hybridize with genetic material from different tissues Matches LIGHT up. Clone the genes that light up

Find chemical which inhibits this enzyme DRUG CANDIDATE Animal Studies (preclinical studies)

Some considerations Look at safety in animals – large doses and long term Chronic – long term- asthma, hypertension (need to take drug for life) Acute – short term – for short term illness (e.g., bacterial infection, take antibiotic for 10 days)

Animal Models Knockout Mice disrupt gene by deliberate mutation – gene blocked at embryo stage Problems Animals may not get disease we get (HIV) Model does not mimic human condition (good model – athero and pigs) PETA – people for the ethical treatment of animals

Timeline for Discovery and Development A. Laboratory and animal studies 6 yrs B. File Investigational New Drug (IND) to FDA C. Phases I- III 7 years D. File New Drug Application (NDA) at FDA: 1.5 years E. Phase IV (post approval) 6 years

IND components – Goes into effect after 30 days if FDA says nothing Clinical Trials IND components – Goes into effect after 30 days if FDA says nothing Previous experiments Chemical structure Toxicity in animals

Purpose Is drug SAFE AND EFFECTIVE??? Predict Toxic Effects Determine Safe Dosage Determine efficacy (effectiveness)

Participant in trial Entry criteria – age, sex, smoking status, other meds Big cities Sign a consent form Voluntary – can withdraw anytime Confidentiality Often paid

$500 million/drug (dropping due to genomics) Cost Cost: $500 million/drug (dropping due to genomics) Success Rate 5000 : 1 Total time 15 years chemical drug 10 years biological drug

Phase I small group of people (20-80) individuals do NOT have disease evaluate its safety; common side effects: Fatigue, nausea, hair loss, vomiting determine a safe dosage range identify side effects 0.5-1.5 years

Pharmacokinetics How drug is: Absorbed Metabolized Excreted Duration of action

Phase II larger group of people (100-300) people with disease effectiveness further evaluate its safety dosage 2 years

Phase III large groups of people (1,000-3,000) to confirm its effectiveness monitor side effects compare it to commonly used treatments Interactions (with other meds) Multicenter trial – many docs; many hospitals

Phase III May be vs. placebo: Placebo effect: measurable, desirable effect; patients don’t know if on drug or placebo Patient feels better even if on placebo Often seen with antidepressants, antianxiety meds

Launch Drug

Phase IV after the drug or treatment has been marketed collect information about their effect in various populations side effects associated with long-term use. New indications: impt for company to extend its patent protection. Eg. Prozac – antianxiety, approved recently for PMDD (premenstrual dysorphic disorder)

Issues Pharmacokinetics how quickly drug is absorbed eliminated from body (clearance) Delivery Problem – injection vs. oral delivery Do patients develop tolerance? Pharmacogenetics Interfere with meds for other diseases – eg. Lower bp but interfere with med for type II diabetes

Placebo When don’t you use a placebo? Drug available already to treat disease Unethical to use placebo

Discovery: Good Laboratory Practices (GLP) Development: Good Manufacturing Practices (GMP) Standard Operating Practices (SOP) Documentation, Documentation, Documentation