Pharmacology Flashcards
What is pharmacology?
Study of the interactions of drugs (chemical substances) with biological systems.
What are the therapeutic effects of drugs?
Prevention, diagnosis, treatment, or cure of a particular disease.
What is the pharmacotherapeutic triumvirate?
Right drug, right dose, right target.
What is Cp?
The plasma concentration (mg/L) of a particular drug, a function of dose, absorption, metabolism, excretion
Drug effects (therapeutic or toxic) are correlated to:
drug plasma concentration, Cp
MEC?
Minimum Effective Concentration (for both desired response and adverse response)
What is the therapeutic window?
Range of plasma concentration of a drug above MEC for response and below MEC for toxicity.
What is the lag period of a drug?
Time between administration of a dose of medicine and time when Cp reaches MEC.
What is the onset of effect?
Time to reach MEC
What is the Duration of action?
Time above MEC
What is steady state for pharmacotherapy?
Rate of drug administration [RATE IN] = rate of drug elimination [RATE OUT].
Multiple doses administered to reach and maintain Cp in therapeutic window.
What is the time to steady state?
4-5 half-lives when maintenance doses are administered at constant interval
What is steady state concentration?
Average Cp after steady state achieved
What is a dosage regimen?
Key element in pharmacotherapeutics, designed to ensure that the desired steady state drug level is maintained in the therapeutic window. Balances rate of drug elimination with prescribed rate of drug administration.
What are the five elements of a prescription?
Drug Dose Route Frequency Duration
What are the four broad categories of critical knowledge about any drug?
Pharmacodynamics/Mechanism of Action
Pharmacokinetics
Therapeutic Uses
Adverse Drug Reactions/Side Effects/Drug-Drug Interactions
What are pharmacodynamics?
Most important basic science characteristic of a drug, its Mechanism of Action
Why is Mechanism of Action important?
Enables identification of a drug target in the body (site of action) and the identification of the therapeutic category of a specific drug.
What is a drug target?
Commonly a membrane or intracellular receptor, an enzyme in a critical biosynthetic pathway, or a membrane transport protein.
What can drugs do and not do?
Drugs either enhance or block a normal physiological pathway. Drugs do not have unique actions
Why learn physiology?
Aids in identifying potential drug targets for drug action, as well as how the target should be manipulated (enhanced or blocked) to treat a given disease.
What are pharmacokinetics?
The processes of drug absorption, distribution, and elimination - very important (but apparently under-appreciated) for designing dosage regimens.
What is bioavailability, F?
How much of a dose of drug reaches its target.
What is time to peak effect?
How fast a drug reaches its target to achieve Tmax or Cmax.
What is the Volume of Distribution Vd?
Volume of body compartment (L) (i.e., plasma, interstitial space, cellular space, combination) into which an administered drug is expected to dilute. Dose (mg) administered to obtain desired concentration (mg/L).
What is drug absorption?
Passage of drug from site of drug administration into blood.
What is drug distribution?
Movement of drug from bloodstream to tissues, where it can access targets for both therapeutic and side effects of the drug.
What are some considerations of drug distribution?
Drug-protein binding, passage across blood brain barrier or placenta, selective accumulation affecting drug efficacy or toxicity (lungs, bone, ear, kidney/urine, saliva, breast milk).
What is Route of Administration?
Site of application of a drug into or on the patient. Drugs are administered to obtain either systemic or topical (local) action.
What is drug elimination?
Refers to the elimination of drug activity following drug administration by the combined processes of metabolism and excretion.
What is clearance, CL?
Combined effects of drug metabolism and excretion.
Where are drugs metabolized?
Liver
Where are drugs excreted
Kidneys, in urine
What is a side effect?
Drug effect on a non-target system at therapeutic doses.
What are extension effects?
Drug effect on target at higher-than-therapeutic doses (dose-dependent and predictable).
What are idiosyncratic reactions?
Not predictable, varies person-to-person, can be immunologic (allergic rxn) or metabolic (hepatotoxicity).
Which side effects of a drug should you know?
Most common, most severe.
Federal government and drugs
1) Controls what drugs may be prescribed or sold directly to the public (FDA)
2) Evaluation process for safety and efficacy
3) Equivalency of brand name versus generic
4) Placement of drugs into prescription or non-prescription categories
State government and drugs
Controls who may prescribe drugs (licensing), except controlled substances requires registration with DEA
Local government and drugs
may pass laws, such as with medical marijuana in colorado
In case of conflict, which laws (federal, state, local) govern?
Strictest laws apply
What are the four basic drug categories?
Prescription
Controlled Substances
OTC
Dietary Supplements
What separates controlled substances from prescription drugs?
Higher potential for abuse.
What separates dietary supplements from OTC drugs?
Dietary supplements undergo no evaluation for safety or efficacy, make no health claims, all statements “not evaluated by the FDA”.
What happened to drugs in 1938?
The Food, Drug, and Cosmetic Act of 1938 (and Kefauver Amendments of 1962) requires that new drugs released since 1938 be evaluated for proof of efficacy and safety before marketing to public is allowed.
What is a drug?
A known molecular entity intended as a therapeutic agent to diagnose, treat, cure, or prevent disease.
What is a dietary supplement?
Defined as a product intended to supplement the diet that contains a vitamin, mineral, amino acid, or herb/botanical and is not represented as food.
Describe the Dietary Supplement Health and Education Act of 1994
Allows for dietary supplements to be sold to the public without prior evidence of safety and efficacy, though a reasonable expectation of safety under directed use is expected.
Why do drugs need a prescription?
Habit-forming or not safe to use without strict guidance from licensed practitioner due to toxicities, methods of use, etc.
Why might a drug be OTC rather than prescription?
self-diagnosable/treatable high safety profile directions understood by ordinary (non-clinical) person method of use not difficult benefits outweigh risks
What act controls the manufacture and distribution of depressant and stimulant drugs?
Controlled Substances Act of 1970
What defines a Schedule I drug?
High abuse potential, no currently accepted medical use (opiates, heroin, hallucinogenic substances, some depressants and stimulants)
What defines a Schedule II drug?
High abuse potential, but accepted medical use (opioid analgesics, hydrocodone +non-opioids, some stimulants (methamphetamine and cocaine!), some barbiturates (pentobarbital))
What defines a Schedule III drug?
Moderate abuse potential, accepted medical use. Abuse may lead to moderate or low physical dependence or high psychological dependence (codeine + non-opioids, some stimulants, some depressants, anabolic steroids)
What defines a Schedule IV drug?
Low potential for abuse, accepted medical use. Abuse may lead to limited physical or psychological dependence (some depressants, some stimulants, benzodiazepines, nonbenzodiazepine hypnotic agents)
What defines a Schedule V drug?
Little potential for abuse (less than Schedule IV), accepted medical use. Can be obtained without a prescription in some states, treated like Schedule III-IV in Colorado
How do you prescribe Schedule I drugs?
You can’t (legally).
How do you prescribe Schedule II drugs?
Must be in ink in prescriber’s handwriting, cannot be telephoned to pharmacist and cannot be refilled (emergency provisions exist)
What about decimal points in dosage amounts?
Always lead, never trail with a zero, i.e.,
2 not 2.0
0.2 not .2
How many grains in a gram?
15.43
How many grams in an ounce?
28.35 (30)
How many mL per drop?
0.05
What determines therapeutic or toxic drug affect?
Cp
What is pharmacokinetics concerned with?
Absorption, distribution, and elimination (metabolism and excretion) of drugs.
What is an LD?
Loading Dose, a single dose designed to reach a specified Cp
What is MD
Maintenance Doses, multiple doses designed to maintain a specified average plasma level at steady state
What is drug absorption?
Movement of a drug compound from the site of administration into the plasma compartment.
What is F?
Bioavailability, the extent of absorption from non-intravenous site of administration.
What is bioavailability used for?
Convert oral doses to intravenous doses and vice-versa
What is drug distribution?
Movement of drug from the plasma compartment to site of action, or target
What is Vd?
Volume of distribution, describes extent of movement of drug throughout various body compartments, used to convert a drug dose to a concentration (dilution factor)
What is drug elimination?
Metabolism and excretion of parent drug or drug activity from the plasma compartment
What is CL?
Clearance, measure of ability of body to remove drug from plasma compartment, related to elimination rate constant ke
What is Clearance used for?
Determine interval between doses necessary to maintain
What is the time to reach Cpss
4-5 half-lives
What is the time to eliminate a drug from plasma
4-5 half-lives
How are drugs metabolized?
Mostly by post-administration enzyme-catalyzed chemical structure transformation.