Basic Pharmacology

Question 1

What are drugs

Answer 1

• any substance that alters the physiology of the body but is not a food or nutrient
• usually derived from compounds found in plants
• definition often accounts for the intention of the user
• examples
  
  • vitamin C in pills = drugs
  • vitamin C in fruit/veg = not drug

Question 2

Psychoactive drugs

Answer 2

• aka psychotropic drugs
• act upon CNS to alter brain function resulting in changes to perception, mood, consciousness and behaviour
• may be used recreationally
  
  • or as entheogens for ritual or spiritual purposes
  • or therapeutically

Question 3

Formulation

Answer 3

• trade name refers to formulation
  
  • the way the medicine is made
• includes both active ingredient and excipients (non active ingredients)

-drugs with exact same ingredients could have very different psychoactive properties due to different formulations

Question 4

Describing drug doses

Answer 4

• doses: mg/kg (body weight)
• concentration at site of action
• TD50: median toxic does
  
  • undesirable effects

Question 5

Therapeutic index

Answer 5

• TI=LD50/ED50
• higher number = safer drug
• alcohol has lowest TI

Question 6

Potency

Answer 6

• more potent drug produces effect at lowest dose

- heroine vs morphine

Question 7

Efficacy

Answer 7

-maximum effect a drug will produce that is desirable

Question 8

Synergistic effects

Answer 8

• potentiation
• the whole is greater than the sum of the parts
• greater than additive effect

Question 9

Over effects

Answer 9

• combination of substances produce something different than either substance alone
• Ayahausca effect
  
  • DMT = Harmine = profound hallucinations

Question 10

Pharmacodynamics

Answer 10

What the drug does to the body

Question 11

Pharmocokinetics

Answer 11

What the body does to the drug

• routes of administration
• absorption
• distribution
• excretion/elimination

Question 12

Subcutaneous injection

Answer 12

• absorption rate dependent on blood flow to injection site
• tends to be slow
• provide even sustained delivery over time

Question 13

Intramuscular

Answer 13

• slower absorption than iv
• faster than sc
• usually to deltoid or gluteus

Question 14

Intraparetoneal

Answer 14

• directly into organs

- common in lab animals

Question 15

Other injection methods

Answer 15

• IVC
  
  • intracerebroventricular
  • into ventricles
  • brain and capital cord surrounded by CSF
  • ICV injections directly into ventricle via cannula
  • bypass BBB

Question 16

Factors that influence absorption from injection site

Answer 16

• temp
  
  • heat increases blood flow
• once in blood drug must pass through walls of capillaries in order to enter circulation
  
  • drug diffuses through pores

Question 17

Intranasal administration

Answer 17

• enters nasal cavity in mucosa membrane then diffuses into blood
• some enters lungs
• some runs down into stomach
• further away from heart so slower reaction time than inhalation

Question 18

Oral administration

Answer 18

• some absorption from stomach but mostly from small intestine
• tissue made of cells surrounds by bilipid membrane
• rate of absorption controlled by ability of drug molecules to dissolve in lipids
  
  • lipid solubility
  • high lipid solubility = easily dissolved = faster onset of effects

Question 19

Lipid solubility

Answer 19

• olive oil partition coefficient
• when a drug is dissolved in a mixture of oil and water, different proportions of the drug will end up dissolved in the oil and water
• high partition coefficient means that most of drug will end up in oil
  
  • high lipid solubility
• low coefficient mean that most will end up in water
  
  • low lipid solubility
• high lipid soluble drugs can diffuse through membrane and be absorbed from small intestine
• low lipid solubility diffuse slowly into blood from small intestine
• when molecule of a drug have an electric charge (IONIZED) they are NOT lipid soluble at all