Pharmacodynamic Phase Flashcards
PHARMACODYNAMIC PHASE
Study of drug concentration and its effects on the body
Drug response can cause?
a primary or secondary physiologic
effect, or both.
Dose Response
Relationship between the minimal versus the maximal amount of drug dose needed to produce desired drug response
Maximal Efficacy
Maximum drug effect
Onset
Time it takes to reach minimum effective concentration after a drug is administered.
Example: start of lowering temperature after fever
Peak
Drug reaches the highest blood or plasma concentration
Example: Totally healed
Fastest drug to reach the peak are those given in?
IV: 3-10minutes
Oral route: 1-3 hours
Duration
Length of time drug has a pharmacologic effect.
Agonists
Produce a response
Example: Epinephrine
Antagonist
Block a response.
Example: Drug - Cimetidine, Receptor - Histamine
Nonspecific Drug Effects
Drugs that affect various body sites
○ Eyes, heart, lungs, GI tract
Nonselective Drug Effects
drugs that affect various receptors
○ Alpha 1, Beta 1, Beta 2
CATEGORIES OF DRUG ACTION
- Stimulation or depression (Nervous System)
- Replacement (Taking insulin for Diabetes)
- Inhibition, Antimicrobial, Cytotoxic, or Killing of Organisms (Antibacterial, Antifungals)
- Irritation (Constipation: can irritate the lining of GI tract to
perform peristalsis) - Modification of Immune Status (Anti-inflammatory drugs)
Therapeutic Index
Estimates margin of safety of a drug
through the use of a ratio that measures the effective dose
and the lethal dose
Drug with Low TI
has a narrow margin of safety (hindi ganun ka-safe, needs to be monitored for toxic effects even if tama ang pagadminister).
Drug with High TI
has a wide MOS (Margin Of Safety) (very safe).
Therapeutic Range
Should be between the minimum effective concentration in the plasma for obtaining desired drug action and the maximum toxic concentration.
Peak Drug Level
Highest plasma concentration of a drug (at a peak level) at a specific time which indicate rate of absorption.
Through Drug Level
Lowest plasma concentration (taken immediately before the next dose; for low TI) of a drug, which measures the rate at which a drug is eliminated.
if a drug’s peak level is high, if a drug’s through level
is high, it means?
toxicity can occur
LOADING DOSE
When immediate drug response is desired, a large initial
dose is given to achieve a rapid minimum effective
concentration in plasma.
Example: Digoxin for CHF, para umepekto agad in improving heart contraction and lessen congestion. Usually has a loading dose.
All Loading Dose are?
one-time dose, then sinusundan lang ng maintenance dose (which is less dosage).
Side Effects
Desirable and undesirable
Example: Benadryl (side effect is drowsiness)
■ Taking a certain drug in the morning while taking an exam, and got drowsy (undesirable)
■ Taking a certain drug in the evening to have a good sleep (desirable)
Adverse Reactions
undesirable (allergic reactions, superinfection, organ toxicity)
Toxic Effects
dangerous and may be considered lethal.
○ Drugs with low TI; can cause neurotoxicity, autotoxicity, hepatotoxicity, and nephrotoxicity
PHARMACOGENETICS
Effect of a drug action that varies from a predicted drug
response because of genetic factors or hereditary influence. (not effective for other race)
Tolerance
Decreased responsiveness over the course of therapy.
Ex: Drug tolerance for narcotics can result in decrease pain relief. To avoid tolerance, drugs must be finished.
Tachyphylaxis
Rapid decrease in response to the drug. Acute tolerance.
PLACEBO EFFECT
Psychologic benefit from a compounds that may not have
the chemical structure of a drug effect
○ Usually done in clinical drug studies
