Lecture 1

Question 1

What does ADME stand for?

Answer 1

Absorption
Distribution
Metabolism
Excretion

Question 2

There are 4 main routes for systemic administration of drugs

Answer 2

• Enteral route
• Parenteral route
• Inhalation
• Transdermal route

Question 3

Enteral routes of administration

Answer 3

Sublingual
Oral
Rectal

Question 4

Parenteral routes of administration

Answer 4

Intravenous (IV)
Intramuscular (IM)
Subcutaneous (SC)
Intradermal injection

Question 5

Topical routes of administration

Answer 5

Epidermic
Irrigation
Instillation

Question 6

Inhalation routes of administration

Answer 6

Vaporization
Gas inhalation
Nebulization

Question 7

What is the difference between enteral and parenteral?

Answer 7

The difference between parenteral and enteral routes of administration is that the parenteral route
completely bypasses the digestive system, eliminating the effects of first-pass metabolism. In contrast,
enteral routes use the digestive system, including the mouth, stomach, small intestine, and anus

Question 8

What are the two types of mucus membranes

Answer 8

1. Respiratory mucosa (lines most of the nasal cavity)- Pseudostratified ciliated columnar epithelium, scattered goblet cells
2. Seromucus nasal glands- contain mucous secreting cells and serous cells

Question 9

Where does intranasal absorption occur

Answer 9

Absorption occurs through thin mucus membranes that line the nasal passages

Question 10

What are some important properties for nasal delivery

Answer 10

molecular size and weight
pH
partition coefficient

Question 11

What size do particles need to be to reach the alveolar sacs?

Answer 11

0.5-1 um. Particles outside this range are either
exhaled or deposited on larger bronchial
airways

Question 12

Advantages of intrathecal therapy

Answer 12

Better analgesia with fewer side effects and a lower dose of drugs
administered as the drug is taken directly to the receptors with a good impact on severe spasticity in adults and children

Question 13

Angles for administration of injection

Answer 13

Intramuscular injection- 90 degrees
Subcutaneous injection- 45 degrees
Intravenous injection- 25 degrees
Intradermal injection- 10-15 degrees

Question 14

What is the bioavailability of intravenous

Answer 14

100%

Question 15

Intramuscular injections are used when?

Answer 15

The intramuscular route is used where effects are desired over a longer period of time than can be
expected after intravenous injection, for drugs that are too irritant to be given subcutaneously, or for oily
solutions, which cannot be given intravenously

Question 16

The skin is comprised of three primary layers

Answer 16

1. The epidermis (provides waterproofing and serves as a barrier to infection)
2. The dermis (serves as a location for the appendages of skin)
3. The hypodermis (subcutaneous adipose layer)

Question 17

What is the stratum corneum?

Answer 17

The stratum corneum is the outermost layer of the epidermis and is
composed mainly of dead keratinised cells (from lack of oxygen and
nutrients).

Question 18

What is the dermis?

Answer 18

The dermis is the layer of skin beneath the epidermis. It contains the
hair follicles, sweat glands, sebaceous glands, apocrine glands,
lymphatic vessels and blood vessels.

Question 19

What is the hypodermis?

Answer 19

Its purpose is to attach the skin to underlying bone and
muscle as well as supplying it with blood vessels and nerves. The main
cell types are fibroblasts, macrophages and adipocytes (the
hypodermis contains 50% of body fat).

Question 20

Factors that affect the absorption of an epidermal
administered drug

Answer 20

1. Damage in the stratum corneum (layer)
2. Region of the body
3. High lipid-water partition coefficient (and small molecular size)
4. Cleansing of the skin (and friction)

Question 21

How do transdermal drug delivery systems work?

Answer 21

Transdermal drug delivery system delivers the drugs through the skin portal to
systemic circulation at a predetermined
rate and maintain clinically the effective
concentrations over a prolonged period of
time.
The drug must traverse three layers, the
stratum cornium, the epidermis, and the
dermis. Of these, the toughest barrier is the
stratum corneum, which consists of 10-25
layers of keratinized cells.

Question 22

What are the four types of wearable transdermal delivery systems?

Answer 22

1. Mechanoresponsive delivery systems
2. Electrically activated delivery skins
3. Bioresponsive delivery systems
4. Light triggered delivery patches

Question 23

Factors in skin permeation

Answer 23

1. Thickness of the skin layer- thickest on palms and soles and thinest on the face
2. Skin condition- permeability of skin is affected by age, disease state or injury.
3. Skin temperature- permeability increases with increase in temp.
4. Hydration state- the greater the hydration, the higher and better the absorption of substances, in particular polar
   substances.

Question 24

What does sublingual mean?

Answer 24

Drug is placed under tongue

Question 25

What does buccal mean?

Answer 25

Drug is placed between gums and lips

Question 26

How long does it take for the effects of sublingual drugs occur

Answer 26

Immediately

Question 27

Orally administered drugs are most absorbed where?

Answer 27

Drug molecules are mostly absorbed from duodenum, jejunum and upper ileum

Question 28

What are the two main processes for the oral administered drugs before the absorption process?

Answer 28

Disintegration and dissolution

Question 29

What is bioavailability?

Answer 29

The fraction of toxin or drug reaching the systemic circulation after administration

Question 30

Bioavailability varies between

Answer 30

0-100% (or 0-1)

Question 31

What is first-pass metabolism

Answer 31

Reduced drug concentration that enters the circulation as a result of metabolism by the liver

Question 32

How do you work out bioavailability?

Answer 32

The bioavailability (F) of a drug delivered via other routes of administration can be determined by the mass of the drug delivered to the plasma divided by the total mass of the drug administered: F = mass of the drug delivered to the plasma ÷ total mass of the drug administered In pharmacologic contexts, an area under the curve graph (AUC) plots the plasma concentration of a drug on the y-axis versus time following drug administration on the x-axis. The area under the curve is directly proportional to drug absorption. Recall that the bioavailability of any drug delivered intravenously is theoretically 100%, or 1. This allows for convenient calculation of the bioavailability of drugs not delivered intravenously. By dividing the area under the curve of a drug delivered orally, for example, by the area under the curve for the same dose of that same drug delivered intravenously, one may successfully calculate the bioavailability of the oral drug. F = AUC for X route of administration ÷ AUC for IV administration Bioavailability

Question 33

Drug Related Factors That Affect Bioavailability

Answer 33

* Particle size, * Crystalloid structure, * Salt compound / free, * Degree of hydration, * Drug formulation affects the dissolution and disintegration

Question 34

Patient Related Factors That Affect Bioavailability

Answer 34

* Differences in first-pass metabolism, * drug metabolism differences between individuals (pharmacogenomics), * diseases that affect the GI motility, * age, * gender, * body weight, * drug-drug or drug-food interactions

Question 35

Physiological Factors That Affect the Absorption from GI Tract

Answer 35

* Stomach emptying time * Taking pills on a full or empty stomach (generally doesn’t affect the absorption ratio but it affects the absorption rate) * Drug-food interactions may be important. * Absorption of drugs which are taken on an empty stomach starts earlier and it reaches the effective plasma concentration earlier than expected. * Some drugs are recommended to be taken with food to minimize the irritant effect of the drug to the gastric mucosa. * The motility of intestines (constipation or diarrhoea)

Question 36

Advantages of rectal routes of administration

Answer 36

*Can be used when oral route is unsuitable (e.g severe vomiting, uncooperative or unconscious patient) * Useful when the drug causes GIT irritation *NO first-pass elimination

Question 37

Disadvantages of rectal routes of administration

Answer 37

* Absorption can be irregular and unpredictable * Less convenient than other route * Low patient acceptability in the UK *Risk of rectal bleeding *Increased bacteremia risk for immunosuppressive patients *Decreased absorption in diarrhea and constipation.