Introduction/Concepts Flashcards
Prototypes
- individual drugs that represent an entire group of drugs
- Most often the first drug developed but not always
- IS the standard to which newer drugs are compared
- some prototypes are replaced overtimes
- not all classes have prototypes
Ex:
morphine is a prototype for opioid analgesics
penicillin is a prototype for anti-bacterials
Drug Law: Pure Food and Drug Act
Official standards and requirements of accurate labeling of drug products
Drug Law: Durham-Humphrey Amendment
Desginated drugs have to be prescribed by a physician and dispensed by a pharmacist
Drug Law: Comprehensive Drug Abuse Prevention and Control Act, Title II, Controlled Substances Act, Categories of controlled substances
Regulates the distribution of narcotics, categorizes it by its usefulness and its potential for abuse
Drug Law: Orphan Drug Act
Manufacturers get decreased taxes and competition for those who produce drugs to treat disorders that affect very few people
Categories of Controlled Substances: Schedule I
Not approved for medical use
- heroine, LSD, ecstacy, and marijuana (depends on state law)
Categories of Controlled Substances: Schedule II
High abuse potential
- codeine, morphine, oxycodone, hydrocodone, barbituates
Categories of Controlled Substances: Schedule III
Less abuse but high potential for dependence
- anabolic steroids
Categories of Controlled Substances: Schedule IV
Some potential for abuse
- diazepam, valium, lorazepam, ambien
Categories of Controlled Substances: Schedule V
Contain moderate amount of controlled substances
- cough medicine with codeine or hydrocodone
FDA Pregnancy Categories
A - no fetal risk
B - animal studies show no risk
C - a potential risk, drugs may be used
D - Evidence of fetal risk, but potential benefit to mother may be acceptable
X - demonstrated fetal risk outweighs any benefit
Drug approval process
- Overseen by the FDA for safety and effectiveness
- Starts with animal studies
- Next step is human studies
Human Studies: Phase I
few doses are given to a certain number of healthy people to determine safe dosages, route of administration, absorption, metabolism, excretion and toxicity
Human Studies: Phase II
few subjects with target disease being studied given doses – responses are compared to the healthy subjects
Human Studies: Phase III
drug is given to a larger, more representative group of subjects – double blind, placebo controlled study.
Human Studies: Phase IV
allows the drug to be marketed for general use (in larger amounts) and allows the manufacturer to monitor and report the drug effects.
- this is where the big adverse effects can be found.
Sources of Drug Information
- American Hospital Formulary Service and Drug Facts and Comparisons - Used by pharmacists
- PDR - big book - compilation of packet inserts
- Pharmacy
- Drug handbooks
- FDA
Pharmacokinetics
Actual movement of drug through the body and what the body does with the drug
Absorption
- From the time the drug enters the body to the time it enters the bloodstream to be circulated
- Things that effect absorption: dosage of drug, form, route of administration, blood flow to the area, GI function and presence of food.
- Parenteral (IV, SubCut, IM)
- Enteral: (po, sl) - po is slowest route
- Topical: (transdermal, inhalation)
Distribution
- the transport of drug in the bloodstream within the body
- drugs are carried by blood and tissue fluids to the site.
- Depends on adequate circulation: goes faster to organs with big blood supply (liver/heart/kidneys) and slower to others
- *Protein binding (albumin): drugs bound to proteins are pharmacologically inactive. Only free/unbound proteins of the drug act on body cells. Protein binding allows some of the drug to be stored and released as needed and allows for a consistent blood level and less chances of toxicity. Highly bound drugs have a long duration of action.
- Low albumin - must greater risk for toxicity because there is less protein to adhere to.
- blood brain barrier: capillaries with very tight wall limit the movement of drugs into brain tissue. Protective of CNS but makes treating brain issues more difficult.
- Most drugs cross the placenta and can effect the fetus - same goes with breastfeeding
Metabolism
- Biotransformation: drugs are inactivated by the body. Active drugs changed into inactive metabolites and excreted.
- Most drugs are lipid soluble, which aids the movement across cell membrane. Liver enzymes convert fat soluble drugs into water soluble metabolites so they can be excreted by the kidneys.
- Enzyme induction: drugs stimulate liver cells to produce larger amounts of drug metabolizing enzymes.
- Enzyme inhibition: concurrent administration of 2 or more drugs that compete for the same metabolizing enzymes
- *First pass effect: some drugs are extensively metabolized in the liver. Only part reaching the systemic circulation – large first pass effect = a lot of the drug is metabolized in the liver and does not reach the body for use.
Excretion
- Elimination of drug from the body by the kidney unchanged or as metabolites and excreted in the urine.
- oral drugs that are not absorbed are excreted via the bowel.
- serum drug level: when the lab can actually measure the amount of drug in the blood at a particular time and can indicate onset/peak/duration of the drug action
- serum half life: the time required for the serum concentration of the drug to decrease by half (50%). Determined by the drug’s rate of metabolism.
- A drug with a short half life requires frequent administration.
- When a drug is given at a stable dose, 4-5 half lives are required to achieve a steady state concentration - that’s why some drugs take several days to become therapeutic.
Variable that affect drug action
- Dosage: low or high = bad
- Route: IV = fast; po = slow
- Drug-Diet: Drug dependent - some drugs should be taken with food .. some without.
- Drug-drug interactions:
- additive: two drugs with similar actions creating a bigger effect
- synergism: two drugs with different sites/mechanism of actions producing a greater effect when taken together
- interference: one drug disrupts the metabolizing effect of another drug
- displacement: one drug displaces another drug from its plasma protein binding site, which increases the effect of the displaced drug
Common adverse effects
- CNS - confusion or stimulation
- GI - N/V/D
- Hematologic - bleeding
- Hepatotoxicity - liver toxicity
- Nephrotoxicity - kidney toxicity
- Hypersensitivity - can occur with any drug
- Fever - inflammatory response
- Idiosyncrasy - unexpected reaction when given the first time
- Drug dependence - psychological/physiological
- Carcinogenicity - ability to cause cancer
- Teratogenicity - abnormal fetal development
- Tolerance - body getting used to it
- Cross tolerance - tolerance to pharmacological related drugs
Administration responsibilities
Five rights: drug, dose, patient, route time
Legal order: name, drug, dose, route, frequency plus date, time, signature of ordering prescriber
