Lecture 25 - formulation and delivery of CNS systems (ageing)

Question 1

how does donepezil cross the BBB?

Answer 1

carrier mediated transport (organic cation transporters such as choline transport system)

Question 2

how does rivastigamine cross the BBB?

Answer 2

diffusion

Question 3

how does galantamine cross the BBB?

Answer 3

choline and carnitine transport systems

Question 4

how does memantine cross the BBB?

Answer 4

organic cation/ carnitine transporter

Question 5

what formulation is galantamine available as?

Answer 5

conventional tablets reminyl, modified release capsules (reminyl XL), solution (reminyl),

Question 6

what are disadvantages of conventional tablets?

Answer 6

poor bioavailability of some drugs, local irritant effects, harm caused to the GI mucosa, high number of drugs to take at the same time so risk of mistakes, difficulty to remove from blister packs or containers and may not remember to take their medication. difficulties to swallow - dysphagia.

Question 7

describe donepezil dosage and its brand name of conceptional tablets

Answer 7

donepezil aricept are coated tablets to facilitate swallowing.

5mg od at night time. can be titrated up to 10mg after 1 month if no side effects

side effects include nausea, vomiting, headaches, muscle cramps, fatigue, and insomnia

Question 8

describe memantine dosage and its brand name of conceptional tablets

Answer 8

ebixa are 5mg once daily and can be titrated up max 20mg. undesirable side effects are somnolence, hypertension, headache, dizziness and constipation

Question 9

describe dispersible tablets of donezepil.

Answer 9

donezepil should be taken in the evening, t bedtime. should be placed on the tongue allowed to be dispersed and swallowed. disintegration of the tablet in the mouth within 1 minute in the presence of saliva

Question 10

what are advantages of dispersible tablets?

Answer 10

suitable for patients who cannot swallow tablets or capsules and fast drug release

Question 11

what are examples of dispersible donzepil and memantine brand names?

Answer 11

donepezil hydrochloride (Aricept Evess®), memantine (Valios®)

Question 12

descried modified release capsules of galantamine and their brand name

Answer 12

Galantamine (Reminyl XL®): capsules containing prolonged-release granules coated with an indigestible ethyl cellulose shell
Slow release of the drug

• These capsules must not be opened prior to administration
• Not suitable for patients with swallowing difficulties
• Should be administered once daily in the morning, preferably with food
• The capsules must not be chewed or crushed.

Question 13

describe advantages and disadvantages of liquid solution and examples of alzeihmers disease drug brand names

Answer 13

Advantages:
- Drug already dissolved
Absorption faster than solid dosage forms or suspensions
- Easy to swallow

• Disadvantages:
• Risk of deterioration faster than solid dosage forms
• Risk of imprecision in the volume taken

: Donepezil hydrochloride (Aricept®), galantamine (Reminyl®), rivastigmine, memantine (Ebixa®)

Question 14

describe the alzeihemrs disease drug patch and its brand name and function

Answer 14

Matrix-type transdermal patch
- Ex: Rivastigmine (Exelon®)
- Application of the patch once a day, at the same time every day
- The patch remains on the skin for 24h
- It will be replaced by a new one at a different site of application (abdomen, thigh, hip, flank, shoulder, or upper arm)

Question 15

what are advantages of patches

Answer 15

Advantages:
- Slow release and long-lasting effect

• Avoidance of hepatic first pass metabolism
• Can be removed easily and quickly in case of adverse reactions
• Application to various body parts: limitation of the risks of contact sensitization (erythema, edema, vesicles)
• High patient compliance

Question 16

what are disadvantages of patches?

Answer 16

Limitations:
- No exposure to external heat sources: risk of increasing the rate and extent of drug absorption
Overdose