Pharmacology Flashcards
Who monitors drugs for the potential of abuse
DEA (Drug enforcement agency)
Drug schedules
I) Highest- No accepted medical use (heroin, LSD)
II) High- Rx required, opioid narcotics (oxycodone, morphine, hydrocodone)
III) Moderate- Rx required, codeine mixtures (Tylenol 3)
IV) Less- Rx required, anti anxiety, sleeping meds, tramadol
V) Least- No Rx required, codeine containing cough syrups
Schedule II must be typed or written, require new written script for refill
Schedule III and IV can be telephoned to pharmacy 5 times in 6 months
As schedule number increases, abuse potential decreases
Potency vs efficacy
Potency: Amount of drug needed to produce therapeutic effect
Efficacy: Maximum intensity of effect produced by drug
Potency and efficacy are unrelated, drugs may have different potencies but not the same efficacy
Efficacy- Y axis
Potency- X axis
Agonist
Drug produces an effect and has affinity for receptor on cell membrane
Antagonist
Drug counteracts the action of agonist (blocks receptor)
ADME: Absorption
Drug transfer from sight of administration to blood stream
Lipid soluble and nonionized= Easily absorbed
The absorption phase is bypassed when a drug is administered intravenously
The most important site for drug absorption of orally administered drugs is the small intestine
ADME: Distribution
Drug distributed by blood plasma
Factors that influence distribution: Organ size and amount of blood flow, drug solubility, barriers
ADME: Metabolism
Body’s way of changing a drug so it can be excreted
Excreted product is ionized and less lipid soluble (opposite so body can excrete it)
Most common location is the liver. Patients with liver disease or alcoholism may have decreased ability to metabolize drugs. Leads to increased levels in blood which increases toxicity
ADME: Excretion
Drug can be excreted unchanged or as a metabolite (modified)
Kidney (renal) excretion is most common. Can also be excreted through lungs, saliva, breast milk, crevicular fluid
Lipid soluble drugs are not excreted in urine- must be metabolized by liverinto water soluble form to be excreted into urine
Major route of fluoride excretion is in urine
Half life first order kinetics
Constant PERCENTAGE of drug is removed from body per unit of time
(Shorter half life, shorter action of duration, etc)
Half life zero order kinetics
Constant AMOUNT of drug removed from body per unit of time (alcohol and aspirin)
High doses, very long duration of action
Enteral route
Drug placed directly in GI tract- orally or rectally
Drug levels less predictable with oral administration
First pass effect
Orally derived drugs must pass through hepatic portal circulation which can inactivate some drugs.
Amount of drug available to produce systemic effect is reduced by first pass effect
Drugs with high first pass effect require a larger oral dose as high percentage will be deactivated
Parenteral route
Bypasses GI tract
Injection
Inhalation
Topical- contraindicated if surface is ulcerated, burned or abraded
Therapeutic effect
Desirable action of drug
Adverse reaction
Undesirable action of drug
- Side effect: Expected but unwanted response, dose related, non target organs
Toxic reaction
Expected response, exaggeration of therapeutic effect, dose related, target organs
Allergic reaction
Not predicatable, not dose related,
Type I: Immediate hypersensitivity- anaphylaxis
Type IV: Delayed hypersensitivity- contact dermatitis (latex, TB test, transplant)
Therapeutic index
Lethal dose divided by effective dose (LD50/ED50)
Shows safety of drug
Narrow TI: Toxicity more likely
Wide TI: Toxicity less likely, safer drug
TI>10 needed for useful drug
When is epinephrine contraindicated
Cocaine or meth abuser
Clonidine
Adrenergic agonist
Meth
Oral mucosal irritation is a result of the method of drug administration, not the drug itself
Adrenergic drug contraindication
Uncontrolled hypertension and uncontrolled hyperthyroidism- avoid epi or use cardiac dose
Autonomic nervous system drugs
Adrenergic drugs: Mimics SANS
Cholinergic drugs: Mimics PANS
