PED2001 Routes of absorption

Question 1

What are the different routes of drug administration?

Answer 1

Footnote

• Oral
• Sublingual
• Rectal
• Inhalation
• Injection (subcutaneous, intramuscular, intravenous, intrathecal, intravitreal)
• Application to other epithelial surfaces (skin, vagina, nasal mucosa)

Various routes affect the absorption and efficacy of drugs

Question 2

Where does absorption begin for orally administered drugs?

Answer 2

Footnote

In the small intestine

Oral administration is the most common route for small drugs.

Question 3

Which types of drugs are absorbed directly in the mouth?

Answer 3

Footnote

• Non-polar drugs
• Organic nitrates
• Buprenorphine

These drugs bypass the gastrointestinal tract.

Question 4

What factors determine the absorption rate of drugs?

Answer 4

• Drug ionisation
• Lipid solubility

Strong acids and bases cannot be absorbed due to full ionisation.

Question 5

What is bioavailability (F) in pharmacology?

Answer 5

The fraction of an orally administered dose reaching systemic circulation as intact drug

It takes into account both absorption and local metabolic degradation.

Question 6

What influences bioavailability?

Answer 6

• Enzyme activity in the gut wall or liver
• Gastric pH
• Intestinal motility

Bioavailability varies among individuals and conditions.

Question 7

What is the absorption characteristic of rectal administration?

Answer 7

Can be rapid and more complete than oral administration, but may be unreliable

Local effects can be achieved, such as with mesalazine for ulcerative colitis.

Question 8

Name a drug that can be administered sublingually for rapid response.

Answer 8

Glyceryl trinitrate

It is used for quick relief in certain medical emergencies.

Question 9

What are transdermal dosage forms used for?

Answer 9

Steady drug delivery & avoiding presystemic metabolism

Examples include nicotine patches and fentanyl patches.

Question 10

What is a key advantage of nasal sprays for drug administration?

Answer 10

Direct absorption through mucosa overlying nasal-associated lymphoid tissue

This method is particularly useful for peptide hormone analogues.

Question 11

True or False: Intravenous injection is the fastest route of drug administration.

Answer 11

True

It produces rapid and high drug concentration in systemic circulation.

Question 12

What is the purpose of adding adrenaline to local anaesthetics?

Answer 12

To reduce absorption and prolong anaesthetic effect

This technique is used to enhance the duration of action.

Question 13

Fill in the blank: The __________ injection is used for specialized purposes like administering methotrexate for childhood leukaemias.

Answer 13

Intrathecal

This route minimizes peripheral effects.

Question 14

What type of drug is Ranibizumab used to treat?

Answer 14

Wet age-related macular degeneration (AMD)

It is administered via intravitreal injection.

Question 15

What can be a consequence of systemic absorption from eye drops?

Answer 15

Unwanted effects such as bronchospasm in asthmatic patients

Timolol eye drops for glaucoma can cause this side effect.

Question 16

List factors that influence drug absorption in the gastrointestinal tract.

Answer 16

• Gut content (fed vs. fasted)
• GI motility
• Splanchnic blood flow
• Particle size & drug formulation
• Physiochemical factors & drug-drug interactions
• Genetic polymorphisms

These factors can significantly alter the absorption process.

Question 17

What are some drugs intended for local effect in the gut?

Answer 17

• Vancomycin
• Mesalazine
• Olsalazine

These are examples of drugs designed for localized treatment rather than systemic absorption.