Enteral: antibiotics for pre-med or infection, pain medication, anti-anxiety medication
What is the hepatic first-pass effect?
all drugs taken orally must pass through the liver via hepatic portal vein prior to reaching general circulation.
The liver metabolizes drugs, sometimes to such ane xtent that only a small amount of active drug emerges from the liver into the circulatory system
The first pass through the liver can greatly reduce the bioavailability of the drug
What is the sequence of events after administering drugs?
Distribution- including to the site of action, where interaction with the receptor evokes a response
Biotransformation- also called metabolism or detoxification
What is absorption?
process by which drug molecules are transferred from the site of administration to the circulating fluids.
requires the drug to pass through biologic membranes
Why is the rate of drug absorption significant?
it determines when and how much of a drug becomes pharmacologically available to exert its action
What are the physiochemical properties that influence the movement of drug molecules across biologic membranes?
degree of ionization
What compounds cross the cell membranes easily?
nonpolar (nonionized), lipid-soluble
What compounds have difficulty passing the cell membrane?
Polar (ionized), water-soluble (hydrophilic)
What is filtration?
passage of small, water-soluble substances through small pores in cell membranes
most drug molecules are too large to pass through biological membranes by this process
What is passive diffusion?
movement of a drug from an area of high concentration (blood stream) to an area with lower concentration (cell)
diffusion will continue until concentration gradient has been eliminated
passive diffusion does not require energy as compared w/ active transport
What kind of molecules can easily pass through the biologic membrane through passive diffusion?
What is facilitated diffusion?
A drug forms a complex w/ a component of the cell membrane
the drug complex is then carried through the membrane, the drug is released and the carrier returns to its original position
What is active transport?
Movement of a drug from an area of low concentration to an area of higher concentration.
This activity requires energy
How do large, ionized, water-soluble molecules cross biologic membranes?
through facilitated diffusion and/or active transport
What factors affect absorption?
degree of ionization
degree of lipid solubility
presence or absence of food (if administered enterally)
patient compliance with taking medication
other disease states
interaction w/ food, minerals, other drugs
What kind of molecule gets more absorbed?
less ionized (charged), more absorbed
more lipid-soluble more readily absorbed
Where does most drug absorption occur in the body?
upper part of duodenum or small intestine
What is the dissociation constant?
pH at which a drug is 50% ionized and 50% nonionized.
What are the ways of transportation of drugs in the body?
Some drugs travel by binding to protein (albumin) receptors
Some drugs bind to tissue, which can cause chemical effects
What happens when the blood level decreases below the therapeutic level?
the drug will not produce the desired effect
what happens if the blood level increases significantly above therapeutic level?
toxic symptoms may develop
What is the blood brain barrier permeable to?
small, highly lipophilic (fat-loving) molecules
What is the blood brain barrier
not a true barrier, but a selective gatekeeper
What is the primary organ of metabolism?
What is phase 1 biotransformation?
drugs chemical structure is modified through oxidation, reduction or hydrolysis
oxidative metabolism by the hepatic microsomal cytochrome P450 (CYP45) enzyme system is the primary method of drug metabolism
a lipid-soluble drug is changed to a more polar (ionized) and more hydrophilic (water-soluble) metabolite so it is more easily excreted
Drug interactions involving the cytochrome P450 system are common
What is phase 2 biotransformation
molecules on the drug or metabolite from Phase 1 are conjugated (linked) with highly water-soluble compounds such as glucuronic acid to make a more water-soluble product
What factors effect biotransformation?
individual differences in metabolic rate (genetic polymorphism)
pulmonary disease (inhaled drugs)
cigarette smokers (may need more of a particular drug)
Where are the majority of drugs excreted?
alcohol is partially excreted from the lungs
Where are anesthetic gases excreted?
What kind of drugs have been found in saliva?
aspirin, phenytoin, ampicillin, diazepam, penicillin VK and phenobarbital
Where does tetracycline concentrate?
gingival crevicular fluid
What is in the heading portion of the prescription?
prescriber's name, address and phone #
date of prescription
patient's name, address, age and weight
What is in the body portion of the prescription?
Rx: drug name and strength
Disp: quantity to be dispensed
Sig: directions for use
What is in the closing section of the prescription?
prescriber's signature, DEA #, refill info
1kg equals how many grams?
1 gram equals how many milligrams?
1 liter equals how many milliliters?
1cc equals how many ml?
What schedule drug is percocet?
must have written prescription
can call in only in case of emergency
What schedule drugs are vicodin and Tylenol-3?
written or oral prescription allowed
may refill five times w/in 6 months
What drugs may dental hygienists prescribe?
fluoride, fluoride varnish, antimicrobial solutions for mouth rinsing or resorbable antimicrobial agents
What is the cardinal principle of pharmacology?
no drug ever exerts a single action
What age group are most likely to have ADE's?
they organ functions are either not fully developed or progressively declining
associated with the administration of therapeutic dosages of a drug
usually predictable and avoidable
responsible for most ADEs
What are Type-B ADEs
not dependent upon dosage
rarely predictable or avoidable
include hypersensitivity/allergic responses
may be idiosyncratic (genetically related abnormal drug response)
What are clinical manifestations of Type-A reactions?
Cytotoxic reactions: causes by formation of unstable or reactive metabolites following biotransformation. Related to abnormal metabolism and/or excretion
Drug-drug interactions: drugs administered simultaneously may interact w/ each other to cause an unintended response. (response may be pharmacologic, physiologic, chemical or may cause a receptor alteration)
Drug-food interactions: some drugs are incompatible w/ foods when taken simultaneously. Adverse reactions may interfere w/ absorption, metabolism or excretion
Drug-disease interactions: drug prescribed for the treatment of one disease or condition may have an adverse effect on a different medical condition
What is one of the most common drugs associated w/ hepatotoxicity?
pepole often overdose on this drug because it is contained in so many OTC formulations
What are clinical manifestations of Type-B reactions?
oncogenic effects- related to causing malignancy
teratogenic effects- drug-induced damage that occurs to the developing fetus
What are 2 types of idiosyncratic reactions?
What is hyporeactive?
drug produces its usual effect at an unexpectedly high dose, the patient is said to be hyporeactive
what is hyperreactive?
if a drug produces its effect at an unexpectedly low dosage the patient is said to be hyperreactive