Drugs Flashcards
Drugs most commonly enter our bodies in one of six ways
1) Orally (e.g., swallowed when taken by mouth)
2) Absorbed through mucous membranes (e.g., snorted)
3) Inhaled (e.g., smoked or ingested with aerosol)
4) Injection (injected with a needle and syringe)
5) Absorbed through the skin (e.g., skin patch)
6) Rectally (placed into the rectum)
Where is oral drugs absorbed
Upper intestine; they pass through the intestinal mucosa into the blood by a process known as passive diffusion.
Disadvantages of oral administrations
First, it may lead to occasional vomiting and stomach distress. Second, although the amount of a drug that is put into a tablet or capsule can be calculated, how much of it will be absorbed into the bloodstream cannot be predicted accurately because of genetic differences between individuals and because of differences in the manufacturing of the drugs. Finally, the acidic nature of the stomach may break down some drugs before they can be absorbed.
Practically any drug that can be snorted also can be
inhaled
Popularity of inhalation reasons
The popularity of this method arises from two observations:
1) Lung tissues have a large surface area through which large amounts of blood flow, allowing for the easy and rapid exchange of drugs between lungs and blood (often within seconds).
2) Drugs absorbed into pulmonary (lung) capillaries are carried in the pulmonary veins directly into the left side (arterial side) of the heart, and from there, directly into the aorta and the arteries carrying blood to the brain.
In simple terms, this means that the drugs have a direct route to the brain with minimal interference along the way.
Injection methods
1) Intravenous (directly into a vein)
2) Intramuscular (directly into a muscle)
3) Subcutaneous (just under the skin)
Injection permits a more accurate dose because
the unpredictable processes of absorption through the stomach and intestine are bypassed.
Disadvantages of injection
First, the rapid rate of absorption leaves little time to respond to an unexpected drug reaction or accidental overdose. Second, administration by injection requires the use of sterile techniques. Hepatitis and AIDS are examples of diseases that can be transmitted from unsterile injection techniques. Third, a drug cannot be recalled once it is injected.
Rectum absorption is typically done in medical offices when
the patient is vomiting, unconscious, or unable to swallow.
Disadvantages of rectum absorbtion
irregular, unpredictable, and incomplete, and many drugs irritate the membranes that line the rectum.
In the average adult, the heart pumps a volume of blood every minute roughly equal to the total amount of blood in the body.7 Therefore,
the entire blood supply in the body goes through the heart every minute. This means that once blood enters the bloodstream, it makes its way throughout the body in about a minute.
Primary organ for drug metabolism
Liver
Drug metabolism
the act of breaking a drug into smaller molecules. These smaller molecules are called metabolites and are less active than the drug; in fact, they usually are totally inactive. The metabolites then are excreted from the body
The liver contains enzymes that attack the drugs and break them down into metabolites. These enzymes are capable of breaking down nearly every known drug. Several factors influence the effectiveness of these enzymes at breaking down drugs:
1) Genetic: Some people may not have the genes required to create the enzymes necessary to break down drugs.
2) Environmental: factors in our surroundings that can affect drug metabolism.
3) Physiological: age, sex, nutrition, and other factors that influence the body’s behavior
Drugs leave through of the four paths
1) Kidneys (urine) (main)
2) Lungs (only with highly volatile or gaseous drugs such as alcohol)
3) Skin (excreted as sweat, 10-15%)
4) Bile (feces) (Metabolites may be excreted in the feces. More commonly, they are
reabsorbed into the blood and ultimately excreted in the urine.)
other: trace amounts in saliva, tears, breast milk, and hair.
enterohepatic cycling.
Many metabolites of drugs created in the liver are excreted into the intestinal tract in the bile. Hence the intestine is not only a site of absorption, but it is also a site of excretion. The net excretion by this route may be reduced greatly by the subsequent reabsorption into the bloodstream of fat-soluble compounds further along the intestines. In this case, drugs will undergo the process of excretion all over again, and the drug effect is prolonged.
Common stimulants
cocaine, crack cocaine, and methamphetamine.
Short-term effects of stimulants
-Energy
-alertness
-talkativeness
-well-being
-increased heart rate
-increased blood pressure
-Constricted blood vessels
-dilation (opening) of the lungs
-increased respiratory rate; opens airways
-Increased alertness
-Twitching
-Restlessness
-Agitation
When injected or smoked, these drugs cause an intense feeling of euphoria.
With prolonged use, a user may exhibit nervous habits, such as drumming his fingers or tapping a foot.
Impacts of stimulants on driving
-hurried thinking and irritated behavior
-heightened awareness
-dilate pupils; greater sensitivity to light
-agitation and restlessness
-negative impact on fine motor skills
Stimulant effect on heart
-Heart attack
-Arrhythmia
Stimulant effect on brain
-Stroke
-Seizure
-Bizarre or violent behavior
Stimulant effect on lungs and respiratory system
-Snorting leads to damage in the nose and sinuses, and nasal perforation
-Smoking irritates the lungs and causes permanent lung damage in some people
Stimulant effect on esophagus, stomach, intestine
Ulcers or perforation(s) of the stomach or intestines
Liver, kidneys, and pancreas stimulant effect
Sudden failure caused by cocaine
Depressants short-term effects
-Relaxation and reduction of anxiety
-Lower heart and respiratory rates
-Lower brain activity
-Dilated blood vessels
-Decreased blood pressure
-Enlarged airways
-Decreased alertness
-Impaired motor activity
-Clumsiness
At higher doses of depressants, there is
light-headedness, dizziness, drowsiness, slurred speech, and reduced muscle control
Unexpected side effects of depressants
anxiety, nightmares, hostility, and rage
Overdose of depressants
death by respiratory depression, cardiac arrest, or coma
Effect of depressants on driving
-Slowed judgement and reaction time
-Sluggish; unreactive; “asleep at the wheel
-Dilated pupils
-Sedated; sluggish; clumsy
-Negative impact on all motor skills; lack of coordination
Effect of depressants on heart
Pulmonary vessel dilation, weakened heart contractions, blood pooling.
Effect of depressants on brain
Ready access to brain because they can cross the blood-brain barrier.
-Tolerance
-Dependance
Effect of depressants on lungs and respiratory system
-Inflamed airways
-Pneumonia
