Effects of Drugs
a. Therapeutic effect—what the drug is supposed to do
i. Ex: lower blood pressure, kill bacteria, prevent pregnancy
b. Side effects—secondary or unintended effect
i. Warfarin—spontaneous bleeding
ii
...
Effects of Drugs
a. Therapeutic effect—what the drug is supposed to do
i. Ex: lower blood pressure, kill bacteria, prevent pregnancy
b. Side effects—secondary or unintended effect
i. Warfarin—spontaneous bleeding
ii. Gentamycin—kidney/ototoxicity
iii. Nitroglycerin—injury caused by significant drop in blood pressure
c. Adverse effect—a reaction that is so severe that the drug should be discontinued
i. Chemotherapy that significantly decreases WBC count with increased risk of
infection
d. Drug toxicity—harmful effects caused by overdose, impaired excretion, improper
administration
e. Drug allergy—immunologic response to a drug
i. First exposure—immune system produces antibodies to the drug
ii. Second exposure—reaction occurs
iii. Mild: rash, itching, diarrhea
iv. Severe: anaphylaxis & death
f. Drug tolerance—seen in a person with an unusually low response to a drug. Increased
dosage is required to achieve therapeutic effect
g. Cumulative effect—increasing response to repeated doses of a drug when rate of
administration exceeds excretion of the drug
h. Idiosyncratic effect—unexpected effect that is unique to the patient. The patient has a
reaction that is not generally seen on other patients who are exposed to the same drug.
i. Drug-drug interactions
i. Additive effect: two drugs from a similar therapeutic class produce a combined
summation response. 1+1=2.
1. A diuretic added to an antihypertensive medication will reduce blood
pressure equal to the individual effect of each drug added together.
ii. Antagonistic effect: the use of one drug decreases the effect of another. 1+1<2
1. Naloxone is given to inhibit the effect of morphine
2. Antibiotics decrease vitamin K production in the gut. If a patient is using
warfarin, decreased clotting factors from the liver may cause increased
bleeding because of the warfarin effect
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