1. CHAPTER 3 Sources & Bodily Effects of Drugs
Pharmacology
CHAPTER 3
Sources & Bodily Effects of Drugs

2. A Drug
Any chemical substance taken into the body for the purpose of affecting body function

3. Source of drugs
Way back when….plants were the primary source of drugs used on the human body. Plants such as:
Berries
Bark
Leaves
Resin from trees
Roots
These all aid the body and are still used today
Aloe vera

4. Minerals
These found their way into drugs also:
Iron K+
Sulfur
silver

5. Animals & Humans
Substances lacking in the human body can be replaced with similar substances from animals, glands, organs and tissues
Human cadavers can be used to extract GH

6. Synthetic Drugs
Competitive research and big industries are experimenting with chemicals to discover cures for diseases
HIV research is prevalent now
Dual chemicals on combination are being created like Caduet…it combines Lipitor and Norvasc

7. Effects of Drugs
When introduced into the body, all drugs cause cellular changes known as drug actions
There is then some physiological change
Drugs are categorized by:
Systemic effect or
Local effect

8. Systemic Effect
This reaches widespread areas of the body like acetaminophen suppository
When you give Tylenol PR, it has the ability to absorb and get distributed throughout the body to cause a general reduction in fever

9. Local Effect
This is limited to the area of the body where the medicine is administered such as:
Dibucaine or Nupercainal, this med is applied rectally and only affects the rectal mucousa to reduce hemorrhoidal pain

10. What is the process that makes a med work when taken orally
Within the body, drugs undergo several biological changes and there are 4 drug processes that occur:
1. Absorption – getting into the bloodstream
2. Distribution – moving from the bloodstream into tissues and fluids of the body
3. Metabolism – physical and chemical alterations that a substance undergoes in the body
4. Excretion – eliminating waste products of drug metabolism from the body

11. Interruption
There cannot be any interruptions in any of the 4 processes or the drug will not be properly processed by the body

12. Absorption Takes place in areas such as:
Mucosa of stomach, mouth, small intestine or rectum
Blood vessels in the muscles or sub Q tissues
Dermal layers
If administration of any med is done incorrectly, the drug may be destroyed before it reaches the bloodstream such as giving antibiotics on a full stomach vs. on an empty stomach

13. Absorption of Tetracycline
Ph plays a big part in absorption
Drugs of alkaline nature do not absorb well through the stomach
Tetracycline is recommended to be given on an empty stomach so that the ph is not altered
If tetracycline is given with milk or antacids, it will not be absorbed properly

14. Infants and medications
Syrups and solutions may not be absorbed well if infants drink formula first

15. Lipid Solubility
Substances high in lipid solubility are quickly and easily absorbed in the mucosa of the stomach

16. Presence or absence of food in the stomach
Food in the stomach tends to slow absorption d/t a slower emptying of the stomach

17. DISTRIBUTION
The primary site of process is through capillaries and across cell membranes
Poor circulation/impaired flow of blood may prevent the drug from reaching tissues
Some drugs have targeted tissues that it goes to and works well in, some drugs can cross placenta barrier causing problems for baby

18. Metabolism
When the drug reaches the liver, it is broken down and altered to more water-soluble by-products, thus the new drug may be easier excreted by the kidneys
If a pt has a broken liver, how will the break down the med? The med accumulates and becomes toxic

19. Excretion Most medications are eliminated from the kidneys
Some meds are eliminated through the lungs like exhaled gases from anesthesia
If a drug is not excreted properly, a cumulative effect may occur and cause toxicity.
We don’t need a cumulative effect of meds, they are designed to be given in just the amount to make them work

20. Digoxin has this cumulative effect and drug levels must be obtained
Dig is used to slow the HR, if it accumulates, what will happen?
Bradycardia

21. What other things affect the speed and efficiency of a drug?
AGE – metabolism and excretion are slower as we age leading to possible cumulative effects. Children react more rapidly and in unexpected ways
WEIGHT – generally, the bigger the pt, the more medicine that person would receive. There is an individual variation in the sensitivity of meds. Some meds are weight based, especially in children

22. SEX - women respond differently to meds than men do
SEX - women respond differently to meds than men do. The ratio of fat per body mass differs and hormone levels differ. Pregnant women must not take drugs or limit what they take.

23. Physiological State
When a person feels good, they are more productive, when they feel good while on their medicine, they are more likely to continue to take it

24. Placebo Effect
The more positive the pt feels about the med he is taking, the more positive the physical response
PLACEBO – an inactive substance that resembles a medication, although there is no drug present
Example : birth control has 3 weeks of hormone pills and 1 week of placebo, it’s usually to remind the taker, to keep taking this important pill

25. Drug Interactions
Be careful when combining meds, one can affect the other and even make it not work well or cancel out its effects

26. Terms used to describe drug interactions:
Synergism – the action of 2 drugs working together simultaneously for an effect that neither could produce alone. These drugs together are said to be synergistic. Phenergan and demerol given together are used to relieve pain, both can be given in smaller amts than if given alone

27. Potentiation
Potentiation – the action of 2 drugs in which one prolongs or multiplies the effects of another. Ultram is used in replacement of a narcotic like morphine. If taken together, Ultram potentiates the effects of the morphine and now it’s like you took 3xs the amount of morphine…can cause trouble
Or like Tetracycline potentiates warfarin

28. Antagonism
Antagonism – when one med cancels out the effect of the other med.
Such as narcan to reverse the effects of demerol or morphine if pt had respiratory depression

29. Drs. Must be knowledgeable about all of these terms because if they order meds that react with each other, pts will run into trouble

30. Dosage
Is defined as the amount of drug given for a particular therapeutic or desired effect

31. Minimum dose
Smallest amount of a drug that will produce a therapeutic affect
Example: Tylenol lists dosages on the back of the bottle
(Range of Tylenol is 10-15mg/kg)
Bottle recommends the minimum dose

32. Maximum Dose
Largest amount of a drug that will produce a desired effect without producing symptoms of toxicity
Range of Tylenol 10-15mg/kg 15mg/kg is the maximum dose allowed

33. Loading Dose
Initial high dose (often a maximum dose) used to quickly elevate the level of the drug in the blood (often followed by a series of lower maintenance doses)
Drs. Order this with the 1st doses of pain medicine, they want to get the pain under control quickly
When you are ordered an antibiotic for strep, Dr. tells you to take 2 tabs tonight, to load up on the med

34. Routes to administer meds
GI Tract :
Oral – P.O.
Nasogastric tube - NGT
Rectal - PR

35. Parenteral Routes (these include anything other than the the GI tract):
Sublingual or buccal- SL
Injection routes –
Intravenous – (IV)
Intramuscular – (IM)
Subcutaneous – (Sub Q)
Intradermal – (ID)

36. Topical – (T)
Dermal – (D)
Mucosal -
Inhalation – breathing it in

37. The good with the bad…
There are advantages and disadvantages of taking meds in any of the listed routes:
P.O. meds take longer to work than IV
We would like to try and give all meds by mouth if possible…this is the normal way
IV route is the fastest

38. PATENT Wide open, to keep clear and free
Used often with IVs or feeding tubes
Example:
You must flush a gastrostomy tube with tap water upon the completion of a feed to maintain the patency of the tubing

39. IV Route Meds must be given in smaller amts through IV
Can be dangerous if not deadly if given too much IV
NEVER GIVE ANY SUBSTANCE IV THAT IS NOT A PATENT SOLUTION.
YOU SHOULD BE ABLE TO SEE THROUGH IT SOMEWHAT. NEVER PINK, OPAQUE YELLOW OR WHITE OR ANYTHING STICKY…NOT USUALLY FOR IV USE

40. Parental routes
This way of giving meds is usually for the sickest pts who cannot take P.O.
If you have a med that is not suitable for the GI tract or absorption, then it’s given another way like vitamin B12, just given in IM form

41. Unexpected Responses To Drugs
These are adverse drug effects
These are what happens to pts who are allergic OR this is what can happen from taking a particular med 

42. Teratogenic effect
The development of abnormal structures in an embryo resulting in a severely deformed fetus
Effects from drug administration by the pregnant mom. Fetus can suffer physical defects or death

43. Idiosyncrasy - A structural or behavioral characteristic peculiar to an individual or group
Unique, unusual response to a med that makes one person react differently than another, hmmm… peculiar isn’t it?
When doses of a drug that would have a known and predictable effect cause a toxic or opposite effect, an unusual effect or no effect, hmm… peculiar isn’t it?
It can manifest as an accelerated response to the usual therapeutic dose of the drug hmm… peculiar isn’t it?

44. Paradoxical – seemingly contradictory but demonstrably true
Opposite effect from that which is expected
Such as that benadryl acting opposite of how it’s really supposed to act
Benzodiazepines have been known to cause severe behavioral changes such as mania, schizophrenia, anger, impulsivity, and hypomania

45. Tolerance
Decreased response to a drug that develops after repeated doses are given. Now to achieve the desired effect of the med, the person must increase the normal dose just to get some type of effect. If this doesn’t work, the drug is stopped and another drug is used
Tell story of Jenny and Benadryl and people who take narcotics

46. Dependence
Acquired need for the drug that may produce psychological or physical symptoms of withdrawal when the drug is discontinued
Tell Andy story about increase need for narcotics and withdrawal symptoms

47. Psychological Dependence
Involves only a psychological craving, no physical symptoms of withdrawal are present other than anxiety
Smoking cessation causes both psychological and physical dependence
Smoke with drinking and every time you drink, you need to smoke, even after you have stopped, it’s habit

48. Physical Dependence
Exists when cells actually have the need for the drug
SYMPTOMS OF WITHDRAWAL:
Retching
Nausea
Pain
Tremors
Sweating
Can cause death if in withdrawl too long

49. Hypersensitivity
When a person has an immune response (allergy) to a drug. Can be of varying degrees:
Mild with no immediate effects. Rash or hives may appear after 3 or 4 days of drug therapy
May develop after uneventful previous uses…body is building antibodies to it and one day POW!!!! Immune response
More likely to exist in pts with other known allergies

50. NAUSEA, VOMITING, DIARRHEA
ARE NOT CONSIDERED SIGNS OF ALLERGIES
These are considered to be more like side effects. Just because someone has these does not mean they should never have these again.
Benadryl can fix some of the side effects that cause discomfort to pts

51. Maintenance Dose
Dose required to keep the drug blood level at a steady state in order to maintain the desired effect
Drs. Will order a PCA pump to keep the same level of pain medicine going continuously, they want to maintain this dose to control pain better

52. Toxic Dose
The amount of drug that will produce harmful side effects or symptoms of poisoning

53. Lethal Dose
Dose that causes death

54. Therapeutic Dose
Dose that is customarily given. Average adult dose is based on a body weight of 150lbs. It is adjusted according to variations from the norm

55. Anaphylactic Reaction
Severe, possibly fatal, allergic response
Signs:
Itching
Urticaria (hives)
Hyperemia (reddened, warm skin)
Vascular collapse
Shock
Cyanosis
Laryngeal edema
dyspnea

56. Treatment of anaphylaxis
CPR
Drugs – epinephrine (adrenaline) to get the heart going and raise BP
Corticosteroid – (solu-medrol) to reduce inflammation
Antihistamine – (benadryl) to suppress histamine to reduce redness, itching, edema

57. Anaphylaxis is seen in…
1. Certain antibiotics, especially penicillin
2. X-ray dyes containing iodides, if a pt has an allergy to shell fish, NO DYE
3. Insect stings

58. Information It’s important to get a history on your patient
You can prevent a reaction or side effects if you are aware of what they can and cannot have
Pts who have allergies should wear med-alert bracelets or necklaces or carry a card in their wallet
If a pt has a sensitivity or allergy to one med, they may have other allergies that haven’t been figured out yet

59. THE END