DAS 104: Pharmacology Study Notes

Pharmacology: Study of drugs, including chemical formulas, uses, and positive and negative effects on body structures.
  - Pharmacology is an ongoing process involving the development of new drugs and encompasses a variety of factors:
    - Metabolism
    - Excretion
    - Adverse effects
    - Administration
    - Warnings and contraindications for drugs

Drug: A chemical that has the potential to produce a change in one or more functions of the body.
Drugs do not give a new function to cells but can only increase or decrease cell functions.

Classifications of Drugs

Natural or Synthetic
  - Natural: Obtained from plants, animals, or mineral sources.
    - Examples: Morphine, digitalis
  - Synthetic: Manufactured in a laboratory by chemists.
    - Examples: Demerol, Prevacid
  - Note: Patients allergic to natural drugs can often take synthetic ones without reactions and vice-versa.
Legal or Illegal
  - Legal: Approved by the FDA (Food & Drug Administration).
    - Examples: Penicillin, aspirin
  - Illegal: Against the law, may be imported illegally, used for non-medical purposes.
    - Examples: Heroin, cocaine
Prescription or Nonprescription
  - Prescription: Requires a written order from a doctor or dentist; dispensed by a pharmacist.
    - Controlled: Drugs have the potential to alter the mind and cause abuse/addiction.
    - Non-controlled: Maintenance medications for medical conditions.
  - Non-Prescription (OTC): Can be bought without a prescription.
    - Examples: [to be provided]

Category A: Safe to take while pregnant.
Category B: Animal studies show no risk to fetus; no risk during 1st, 2nd, or 3rd trimesters.
Category C: Adverse effects in animals, no studies in humans.
Category D: Evidence of risk to humans.
Category X: Evidence of fetal abnormalities or risk; DO NOT TAKE.

1906 - Pure Food & Drug Act
- First attempt to control processing of drugs; previously no testing was required.
1914 - Harrison Narcotic Act
- Mandated prescriptions for narcotics; previously could be bought OTC.
1938 - Pure Food, Drug & Cosmetic Act
- Established controls for drug manufacturing and sales; FDA created.
1970 - Controlled Substance Act
- Established the DEA (Drug Enforcement Agency) to regulate substances with abuse potential.
- Drugs classified into 5 schedules based on abuse potential and dependence.

Control and Requirements: All drugs in these schedules are tightly controlled; prescriptions must include patient name, address, and DEA number of prescriber.
Schedule I (C-I):
- High potential for abuse; no accepted medical use; federal offense to possess.
- Examples: Ecstasy, heroin, LSD.
Schedule II (C-II):
- High potential for abuse; accepted medical use (with restrictions); no refills allowed.
- Examples: Morphine, oxycodone, amphetamines.
Schedule III (C-III):
- Moderate potential for abuse; prescriptions can be telephoned; max 5 refills in 6 months.
- Examples: Vicodin, testosterone.
Schedule IV (C-IV):
- Lower abuse potential; prescriptions can be telephoned; max 5 refills in 6 months.
- Examples: Valium, Xanax.
Schedule V (C-V):
- Least abuse potential; some can be purchased OTC in certain states.
- Examples: Robitussin with codeine, Tylenol with codeine.

Trade Name: Assigned by the manufacturer; capitalized; can have multiple names after patent expiration.
- Can indicate drug use or origin.
Generic Name: One name assigned; remains the same regardless of manufacturer after patent expiration; not capitalized.

Use unbiased sources and clear references such as:
  - PDR (Physicians Desk Reference)
  - Package inserts
  - USP/NF (United States Pharmacopoeia / National Formulary)
  - Internet and textbooks.

Definition: Study of how drugs move through the body, including absorption, distribution, metabolism, and excretion.

Components of Pharmacokinetics

Absorption: Transfer of drug molecules from the site of administration to circulating fluids (blood, plasma).
- Affected by drug properties, route, and solubility (pH, fat solubility, size).
Distribution: Movement of drugs into various body compartments.
- Half-life (T ½): Time needed to eliminate half of the drug from circulation.
- Example of T ½ calculation: [to be provided].
Metabolism (Biotransformation): Process of changing a drug for excretion, primarily in the liver, where enzymes modify drug's pH and make it water-soluble.
Excretion: Elimination of drugs from the body primarily via the kidneys but can also occur through lungs, sweat, saliva, breast milk, and stool.

Patient Compliance: Issues related to misunderstanding or motivation affecting medication adherence.
Psychological Factors: Attitude of the prescriber/staff; placebo effects.
Tolerance: Increased dose requirement for the same effect or reduced effect with the same dose.
Pathologic State: Conditions like hyperthyroidism making patients sensitive to epinephrine.
Individual Factors: Including age, weight, sex, genetic variations, and drug interactions.

Metric System:
  - 1 Kg = 2.2 lbs
  - 60 mg = 1 gr
  - 30 gm = 1 oz. = 30 ml
Household Measures:
  - 5 ml = 1 tsp
  - 15 ml = 1 tbsp
  - 30 ml = 1 oz
  - 1000 ml = 1 qt
  - 500 ml = 1 pt (0.5 L).

Purpose: To save time and space in prescriptions, decrease alterations by patients, and minimize drug diversion.
Exemplary Abbreviations:
a before
gm gram
ac Before meals
gr grain
bid Twice daily
gtt drop
c with
h hour
cap capsule
hs At bedtime
d daily
p after
disp dispense
pc After meals

  - ‘a’ Before
- ‘c’ With
- ‘cap’ Capsule
- ‘d’ Daily
- 'ac' = before meals
  - 'bid' = twice daily
  - 'gtt' = drop
  - 'hs' = at bedtime
  - 'po' = by mouth
  - 'tid' = three times daily
  - 'stat' = immediately.

po = By mouth
tab = tablet
prn = As needed
tid = 3 times daily
q = every
qid = 4 times daily
s = without
sig = Write (label)
stat = Immediately
(now)

Dental assistants should understand how to address patient questions regarding prescriptions.
To write a prescription, do not use the tear-off sheet of the pad, and spell out dispensing numbers clearly.
Keep Rx pads secured and avoid leaving in accessible areas.