ch 3 - adverse reactions

therapeutic effects

• clinically desirable actions

• drugs may act on biologic system to accomplish effects, but lack specificity and can act on many organs

adverse effects

• clinically undesirable reactions

• no drug is free from producing this in a certain number of pts

adverse drug reaction

• undesirable response to drug

• can be exaggeration of the desired response, expected but undesirable response allergic reaction, cytotoxic reaction, or effect on fetus

• occurs at usual therapeutic doses

• potentially harmful

categories of drug reactions

• toxic reaction

• side effect

• idiosyncratic reaction

• drug allergy

• interference with natural defense mechanisms

toxic reaction

an exaggeration of desired response

side effect

• dose related reaction that is not part of the desired therapeutic outcome

• this term and “adverse reaction” are used interchangeably

idiosyncratic reaction

a genetically related abnormal drug response

(ex: eskimos metabolize certain drugs faster than other populations, so larger dose is needed)

drug allergy

• immunologic response to a drug resulting in a reaction such as rash or anaphylaxis

• are not predictable nor are they dose related

interference with natural defense mechanisms

• certain drugs can interfere with body’s ability to fight infection

• can cause pt to more easily get infections and have trouble fighting them

clinical manifestations of adverse reactions

• before use, risks vs benefits must be assessed

• exaggerated effect on target tissues

• effect on nontarget tissues

• teratogenic effect (can cause birth defects)

• local effect

• drug interactions

• hypersensitivity

• idosyncrasy

• interference with nature defense

exaggerated effect on tissues

• overreaction of a sensitive patient or by dose that is too large for that pt

• liver or kidney disease may cause this bc the disease interferes with metabolism or excretion of drug

effect on nontarget tissues

• caused by the nontherapeutic action of dug

• reactions can occur at usual doses but appear more often at higher doses

• a reduction in dose usually reduces adverse reactions

teratogenic effect

• terato = monster

• -genic = producing

• cause congenital malformations and developmental abnormalities if introduced during gestation

FDA has defined 5 pregnancy categories

• A, B, C, D, and X

• A denotes the best or least teratogenic drugs

• X denotes the most highly damaging drugs

local effect

• local tissue irritation

• drugs taken orally can produce GI symptoms such as nausea or dyspepsia (indigestion)

drug interactions

• effect of one drug is altered by another drug

• if drugs have same chemical class, pt will have same reaction

hypersensitivity: allergic reaction

• drug must act as an antigen and stimulate antibody production in a previously sensitized patient

• 4 types of reactions

type I allergic reaction

• immediate hypersensitivity, anaphylaxis (allergic)

• within 1 hour

• anaphylactic shock

• urticaria - hives, rasied rash

• dermatitis

• drugs used in dentistry that have produced fatal anaphylaxis incluse the penicillins, ester local anesthetics, and aspirin

type II allergic reaction

• cytotoxic/ cytolytic

• hours to days

type III allergic reaction

• arthus (immune complexes)

• 1-3 weeks

type IV allergic reaction

• delayed hypersensitivity

• days to weeks

• reactions are mediated by sensitized T lymphocytes and macrophages

• cheap jewelry, trpical benzocaine, penicillin, poison oak, poison ivy

which 2 hypersensitivity reactions are related to latex allergic

type I and IV

mnemonic for hypersensitivity reactions

ACID

idiosyncrasy

a reaction that is neither the drug’s side effect nor an allergic reaction

interference with natural defense mechanisms

a drug’s effect on the body’s defense mechanisms can result in an adverse reaction

toxicologic evaluation of drugs

evaluations of toxic effects of drugs are based on experiements performed with lower animals and clinical trials conducted in humans

a DH’s primary role is

patient education

allergic to one drug =

allergic to drugs in same chemical class