(2) Flashcards
Involves the movement of a drug to the body’s tissues
Distribution
Factors that affect drug distribution:
• Drug’s lipid solubility and ionization
• Perfusion of the reactive tissue
Most drugs are bound to some extent to proteins in the blood to be carried to the circulation
Protein binding
Is a protective system of cellular activity that keeps many things away from the CNS.
Blood brain barrier
Many drugs pass through the placenta and affect the developing fetus in pregnant women.
Placenta and breast milk
The process by which drugs are changed
into new, less active chemicals.
Metabolism (Biotransformation)
Drugs that are taken orally are usually absorbed from the small
intestine directly into the portal venous system.
First pass effect
It deliver these absorbed molecules into the liver, which immediately
transforms most of the chemicals delivered to it by a series of liver
enzymes.
Portal veins
Is the removal of a drug from the body.
Excretion
Routes of Excretion
Skin, Saliva, Bile, Lungs, Feces
is the time it takes for the amount of drug in the body to decrease to one half of the peak level it previously achieved.
Half life
FACTORS INFLUENCING DRUG
EFFECTS
- Gender
- age
- weight
- physiological factors
- Pathological factors
- Psychological factors
- Environmental Factors
- Genetic Factors
- Immunological Factors
- Tolerance
- Cumulation
If a drug is taken in successive doses at
intervals that are shorter than
recommended, or if the body is unable to
eliminate a drug properly, the drug can
accumulate in the body, leading to toxic
levels and adverse effects.
Cumulation
arise because of increased
biotransformation of the drug, increased resistance
to its effects, or other pharmacokinetic factors
Tolerance
A drug is more likely to be effective if the patient
thinks it will work than if the patient believes it
will not work.
Placebo effect
When two or more drugs or substances are taken together, there is a possibility that an interaction can occur,
causing unanticipated effects in the body.
Interactions
Types of interaction
- Drug to drug or drug to alternative
theraphy interaction - Drug to laboratory test interaction
- Drug to food interaction
administration of a particular drug may alter results of tests that are done on various chemical levels or reactions as part of a diagnostic study.
Drug to laboratory test interaction
Some foods increase acid production, speeding the breakdown of the drug molecule and preventing absorption and distribution o f the drug.
• Some foods chemically react with certain drugs and prevent their absorption into the body.
Drug to food interaction
All drugs are potentially dangerous. Even though chemicals
are carefully screened and tested in animals and in people
before they are approved for sale, drug products often cause
unexpected or unacceptable reactions when they are
administered
Toxic effects of drug
Are undesired effects that may be unpleasant or even dangerous
Adverse effects
3 levels of adverse effect (literary review)
- Primary action
- Secondary action
- Hypersensitivity
This type of adverse effect can be
avoided by monitoring the patient
carefully and adjusting the prescribed
dose to fit that particular patient’s
needs.
Primary action
Effects of the drug in addition to the
desired pharmacological effect
Secondary action
