D. Formulations for analgesics

Question 1

What route of administration is used the most ?

Answer 1

Oral

Question 2

Besides oral, what other routes of administration is used for pain management ?

Answer 2

Transdermal

Transmucosal

Intravenous

Epidural

Intrathecal

Nasal

Rectal

Question 3

What are the benefits for intravenous administration ?

Answer 3

• No lag time between administration and action
• Dose can be titrated
• More predicable response compared to other routes

-

Question 4

What is a disadvantages for intravenous administration ?

Answer 4

• Require trained medical staff

- Can be invasive

Question 5

What are the benefits or transmucosal administration ?

Answer 5

• Absorption through oral mucosa (oral cavity)
• Oral cavity is rich in blood vessels therefore has a rapid nest of action
• Absorption is directly into the systemic circulation via the jugular vein. Therefore there is no first pass metabolism
• Non invasive

Question 6

What are the disadvantages for transmucosal administration ?

Answer 6

• Limited surface area of 100cm^2. Only small lipophilic drugs absorbed
• Drug must be potent

Question 7

What are the advantages of transdermal administration?

Answer 7

• Good patient compliance. Single patch can be applied every few days
• It can maintain sustained drug plasma profiles over several days in the therapeutic window
• No dips in dose overnight or dose dumpling

Question 8

What are the disadvantages of transdermal administration?

Answer 8

• Removal of device causes the plasma levels to fall shortly afterwards

Question 9

What is transdermal administration ?

Answer 9

Drug diffuses from the delivery system (containing a drug reservoir) through the epidermis (main barrier in the stratum corners)and dermis (rich in blood supply

Question 10

What are the two routes that a drug can go through in the stratum corneum ?

Answer 10

Hydrophilic keratinised cell and lipid channels

Lipid channels is the main route which usually small molecular weight lipophilic drugs can cross

Question 11

What is the difference between the epidermis and the dermis ?

Answer 11

Epidermis- main barrier is the stratum corneum, which is a chemical and mechanical barrier

Dermis- Rich in blood supply

Question 12

What are the two types of transdermal patches ?

Answer 12

Matrix or monolith systems (drug suspensions)

Rate limiting membrane

Question 13

What are the advantages for rectal amninistration?

Answer 13

• used when oral administration is not appropriate
• Can administer drugs that are affected by the pH of the stomach and enzymic activity in the GI tract
• Can be used for drugs that cause gastric irritation when taken orally
• Infants geriatrics and unconscious patients
• No problem with drug taste
• For Durga that are candidates for abuse

Question 14

What are the disadvantages of rectal administration ?

Answer 14

• Drug has to dissolve in rectal. Not much
• Drug absorption can be reduced by degradation by luminal contents, absorption to luminal contents and defaecation
• Drug is mainly absorption by passive diffusion
• Unpredicable, erratic and incomplete absorption
• Inter and intra-subject variation
• May be difficult to self administer by arthritic or physically compromised patient
• Popularity of dosage form varies culturally, may be unacceptable in some cultures

Question 15

What is intrathecal administration ?

Answer 15

Administration of drug in solution by intrathecal catheter to the spinal cord-subarachnoid space

Question 16

What is cerebrospinal fluid ?

Answer 16

A fluid that cushions the brain and spinal cord

Question 17

True or false? Bulk flow of CSF maybe dominant in determining in determining distribution and pharmacokinetics

Answer 17

True

Question 18

When is intrathecal administration used ?

Answer 18

Chronic pain management , spinal anaesthesia and chemotherapy