Chapter 1: Introduction Flashcards
Describes the effects of the body on drugs, eg. absorption, metabolism, excretion, etc.:
Absorption
Distribution
Metabolism
Excretion
Pharmacokinetics
Denotes the actions of the drug on the body, such as mechanism of action and therapeutic and toxic effects.
Pharmacodynamics
Many drugs found in nature are _____, which are molecules that have a basic (alkaline) pH in solution, usually as a result of amine groups in their structure.
Alkaloids
If drug-receptor binding results in activation of the receptor molecule, the drug is termed an _____.
Agonist
If drug-receptor binding results in inhibition, the drug is considered an _____.
Antagonist
The phase of drug movement from the site of administration into the tissues
Distribution phase
The phase of drug inactivation or removal from the body by metabolism or excretion
Elimination phase
[Weak acid] or [Weak base]
_____ are ionized
- More polar and more water-soluble—when they are protonated
Weak base
[Weak acid] or [Weak base]
_____ are not ionized
- Less water-soluble—when they are protonated
Weak acid
Common routes of drug administration:
- Offers maximal convenience
- Absorption is often slower
- Subject to the first-pass effect, in which a significant amount of the agent is metabolized in the gut wall, portal circulation, and liver before it reaches the systemic circulation
- Bioavailability may be limited due to first pass effect
Oral (swallowed)
Common routes of drug administration:
- Direct absorption into the systemic venous circulation
- Bypasses the hepatic portal circuit and first-pass metabolism
Buccal and sublingual (not swallowed)
Common routes of drug administration:
- Instantaneous and complete absorption
- Bioavailability is 100%
- Potentially more dangerous
Intravenous
Common routes of drug administration:
- Often faster and more complete (higher bioavailability) than with oral administration
- Large volumes may be given if the drug is not too irritating
- First-pass metabolism is avoided
Intramuscular
Common routes of drug administration:
- Slower absorption than the intramuscular route
- First-pass metabolism is avoided
Subcutaneous
Common routes of drug administration:
- Offers partial avoidance of the first-pass effect
- Larger amounts of drug and drugs with unpleasant taste are better administered
Rectal (suppository)
Common routes of drug administration:
- Route offers delivery closest to respiratory tissues (eg, for asthma).
- Usually very rapid absorption (eg, for anesthetic gases).
Inhalation
Common routes of drug administration:
- Application to the skin or to the mucous membrane of the eye, ear, nose, throat, airway, or vagina for local effect
Topical
Common routes of drug administration:
- Utilizes application to the skin for systemic effect
- Absorption usually occurs very slowly (because of the thickness of the skin), but the first-pass effect is avoided
Transdermal
FDA ratings of drug safety in pregnancy:
- Controlled studies in women fail to demonstrate a risk to the fetus in the first trimester
- There is no evidence of a risk in later trimesters
- The possibility of fetal harm appears remote
Category A
FDA ratings of drug safety in pregnancy:
- EITHER animal reproduction studies have not demonstrated a fetal risk BUT there are no controlled studies in pregnant women, or
- Animal reproduction studies have shown an adverse effect (other than a decrease in fertility) that was NOT CONFIRMED in controlled studies in WOMEN in the first trimester (and there is no evidence of a risk in later trimesters)
Category B
FDA ratings of drug safety in pregnancy:
- EITHER studies in animals have revealed adverse effects on the fetus (teratogenic or embryocidal or other) and there are no controlled studies in women, or
- Studies in women and animals are NOT AVAILABLE
- Drugs should be given only when the potential benefit justifies the potential risk to the fetus
Category C
FDA ratings of drug safety in pregnancy:
- There is positive evidence of human fetal risk, BUT
- The benefits from use in pregnant women may be ACCEPTABLE despite the risk (eg, if the drug is needed in a life-threatening situation or for a serious disease for which safer drugs cannot be used or are ineffective)
Category D
FDA ratings of drug safety in pregnancy:
- Studies in animals or human beings have demonstrated fetal abnormalities, or
- There is evidence of fetal risk based on human experience or both, and the risk of the use of the drug in pregnant women clearly outweighs any possible benefit.
- The drug is contraindicated in women who are or may become pregnant
Category X
Clinical trial phase:
- Consists of careful evaluation of the dose-response relationship and the pharmacokinetics of the new drug
- Small number of normal human volunteers (eg, 20–100)
Phase 1
Clinical trial phase:
- The goal is to determine whether the agent has the desired efficacy (ie, produces adequate therapeutic response) at doses that are tolerated by sick patients
- Involves evaluation of a drug in a moderate number of sick patients (eg, 100–200) with the target disease
- A placebo or positive control drug is included in a single-blind or double-blind design
- Carried out under very carefully controlled conditions, and patients are closely monitored, often in a hospital research ward.
Phase 2
Clinical trial phase:
- The goals are to explore further, under the conditions of the proposed clinical use, the spectrum of beneficial actions of the new drug, to compare it with placebo (negative control) and older therapy (positive control), and to discover toxicities
- Usually involves many patients (eg, 1000–6000 or more, in many centers) and many clinicians who are using the drug in the manner proposed for its ultimate general use (eg, in outpatients)
- If the drug successfully completes this phase, an NDA is submitted to the FDA. If the NDA is approved, the drug can be marketed and begin next phase.
Phase 3
Clinical trial phase:
- Represents the postmarketing surveillance phase of evaluation, in which it is hoped that toxicities that occur very infrequently will be detected and reported early enough to prevent major therapeutic disasters
Phase 4
