Exam 1 Flashcards
Preclinical Stage of Drug Development
Identification and animal testing
Clinical Stage of Drug Development
Establish safety and effectiveness in humans
Phase I Clinical Trials
Healthy patients; safe dose and pharmacokinetics
Phase II Clinical Trials
Treat disease in small number of patients
Phase III Clinical Trials
Compare new drug to standard therapy in large number of patients
Graded Drug Response
Can be measured continually up to max response; e.g. numerics like BP or HR
Quantal Drug Response
Effect is either present or absent
Drug Potency
How much drug is required to produce a desired effect
Drug Efficacy
Maximum effect a drug can produce
Drug Selectivity
Ratio of desired response dose to dose that produces undesired effects
Therapeutic Index
Ratio of lethal dose to therapeutic dose of drug
Therapeutic Index of:
2 compared to 10
TI of 2 means double the therapeutic dose is lethal where TI of 10 means ten times the therapeutic dose is lethal
Ion Channel Receptors
Increase flow of Ions altering electric potential.
Rapid Onset and short duration
ACh; GABA; Excitatory AA
GPCR
Work through secondary messengers (cAMP, CA++, IP, DAG)
Available GPCR decreases when stimulated
Risk for rebound when drugs are d/c
Transmembrane Receptors
Hormone binding; phosphorylates tyrosine
Insulin
Partial Agonist
Bind to receptor sites but don’t activate every receptor
Max response is lower than full agonist
Bioavailability
Percentage of the administered drug that is absorbed into central circulation
Ion Trapping
Molecules exist as mixture of charged and uncharged ions depending on their pKa and the environmental pH
Only unionized molecules diffuse so an excess number of ionized drugs d/t pH will change distribution
Protein Binding
Can increase drug in circulation keeping the drug from working at an active site
Deranged physio like low albumin will change drug concentrations and needs to be accounted for
P-glycoprotein
Efflux transporter
MRP1
Efflux transporter
BRCA1
Efflux transporter
Phase 1 Metabolism
Redox reaction
CYP450
Can inactivate or activate a drug
Phase 2 Metabolism
Conjugation Reactions
Generally inactivate a drug and make it more hydrophilic for easy excretion
Breakdown CYP3A4*1
3-Family
A-Subfamily
4-Individual Enzyme
*1-Mutation from wild type
First-Order Metabolism
Fixed fraction of a drug is metabolized per hour
Half-life metabolism
Half-Life Metabolism
1st-50%
2nd-75%
3rd-87.5%
4th-93.75%
Drugs are usually dosed at their half life time
Zero Order Metabolism
Constant amount of drug is metabolized each hour
Enzyme Induction
Increased expression of drug metabolizing enzymes that can speed up or decrease metabolism.
Glomerular Filtration
Small unprotein bound drug molecules are filtered into lumen of nephron
Tubular Reabsorption and Secretion
Active and passive diffusion between the lumen of the nephron and the blood supply
Some drugs target active transporters here inhibiting movement of molecules
WHO’s 6 step model for drug prescribing
Define patient’s problem
Specify therapeutic objective
Choose treatment
Start Treatment
Educate the patient
Monitor Effectiveness
I Can PresCribE A Drug
Indication
Contraindications
Precautions
Cost/Compliance
Efficacy
Adverse effects
Dose/Duration/Direction
Legend Drugs
Contain “Federal law prohibits dispensing without a prescription” label
Schedule I
No Legal Use
Heroin, LSD, mescaline, Illegal Fentanyl
Schedule II
No Refills
Narcotics
Stimulants
Barbitals
Schedule III
Max 5 refills or 6 months
Narcotics mixed with nonnarcotics
Steroids, testosterone
Schedule IV
Benzodiazepines
Schedule V
Loperamide
Cough medications
Pharmacological ADR
Intrinsic; Predictable based on MOA