Drug delivery system mw % +

Question 1

Drug Formulation

Answer 1

• Formulated to allow selective targeting of a tissue site.
• To avoid pre- or systemic metabolism,
• To allow a 24 hour action
• Different drug formulations allow a treatment regime to be tailored to a patients needs, pharmacological characteristics and disease state.

Question 2

What determines the drug delivery system we use

Answer 2

• The dosage
• The frequency of administration
• The timing of administration

Question 3

Oral Medication types

Answer 3

• Solutions
• Suspensions
• Capsules,
• Tablets
• Modified release tablets.

Question 4

Absorption of drugs Via the GI tract:

Answer 4

◦Buccal- above the tongue

◦Sublingual- underneath the tongue

◦Oral

◦Rectal

Question 5

Solutions

Answer 5

• Young, elderly and patients with swallowing difficulties.
• May be given via a naso-gastric or PEG tube
• Drugs given in this way are absorbed extremely rapidly
• Absorption depends on gastric emptying and is most rapid from the small intestine

Question 6

Suspensions

Answer 6

• Young, elderly and patients with swallowing difficulties
• May be given via a naso-gastric or PEG tube
• Absorbed extremely rapidly
• Dispersions of course drug particles in a liquid phase
• The dose can be contained in a small volume
• Good for drugs which are insoluble, unpalatable as they are better tolerated

Question 7

Tablets and Capsules

Answer 7

Note: Dissolution or tablet break down is the rate limiting step in absorption.

Distinct advantages:

• Convenience
• Accuracy of dose
• Reproducibility
• Drug stability
• Ease of mass production

Question 8

Enteric Coated Tablets

Answer 8

• Delays disintegration of the tablet until it reaches the small intestine.
• Tablets are enteric coated to:

◦Protect the drug from stomach acid e.g Omeprazole

◦Protect the stomach from the drug e.g Aspirin

Question 9

Prolonged or Delayed Release Formulations

Answer 9

• Most disorders required prolonged therapy
• Maintains drug levels within a therapeutic range
• Reduces the need for frequent dosing
• The time course for a drug in the body can be prolonged
• Ccontains more of the active drug but releases it more slowly over a prolonged period

Question 10

Prodrugs

Answer 10

• Synthesised inactive derivatives of an active drug which requires to be metabolically activated after administration
• Prolongation of duration of action
• Avoids gut degradation of the drug

Question 11

Buccal and Sublingual Administration

Answer 11

Ideal method for drugs which have extensive pre-systemic or first pass metabolism.

Question 12

Forms of rectal Route

Answer 12

• Suppositories- solid dosage form that is inserted where it dissolves or melts
• Creams
• Liquids

Question 13

Advantages of rectal route

Answer 13

• Useful in the young or old
• Patients unable to swallow
• Drugs may be administered rectally:

◦To treat local conditions such as proctitis

◦To achieve systemic absorption (indomethacin)

◦ Bypass pre-systemic metabolism

Question 14

Vaginal Route

Answer 14

• Pessaries- a medical device
• Creams
• Useful in local disease

Question 15

Injection based drug delivery system

Answer 15

• Provide fast systemic effects bypassing first-pass metabolism
• Drugs can be administered in unconscious or comatose patients
• Drugs having short half-life can be infused continuously

Question 16

Intravenous Administration

Answer 16

Useful when:

• A rapid onset of action is required
• Careful control of plasma levels is required
• A drug has a short half-life

Question 17

Intramuscular Injection

Answer 17

• The drug is given into the muscle mass
• May be insoluble or formulated in an oil base
• Allows a more sustained duration of action up to months
• Depot Injections contraceptive, neuroleptics
• May be painful

Question 18

Subcutaneous Injection

Answer 18

• A common route of administration
• Easy to use and bypasses need for venous access
• Used for insulin, heparin and narcotic analgesics

Question 19

Types of subcutaneous

Answer 19

• Dermojet- needleless injection used for mass inoculation (vaccination)
• Pellet implantation-drug as a solid pellet is implanted under the skin to provide uniform systemic effect .e.g.testosterone

Question 20

Transdermal Drug delivery system

Answer 20

• Adhesive patches containing the drug are applied on the skin
• The drug crosses the skin surface by diffusion by percutaneous absorption (through skin) and goes into systemic circulation
• Bypasses first-pass hepatic inactivation

Question 21

Percutaneous

Answer 21

• Creams,ointments and skin patches
• Drugs can be administered to the skin to achieve a local effect i.e steroids or a systemic effect i.e HRT or nitroglycerin.

Question 22

Skin Patches

Answer 22

• Allows the release of a drug from a reservoir into the skin and then into the systemic circulation.
• Possible to obtain controlled, sustained blood levels of the administered drug such as nicotine, nitroglycerin, opiates, HRT, contraception

Question 23

Inhalation

Answer 23

• Used to deliver drugs directly to the lung for local effect or to achieve a systemic effect I.e anaesthetics
• Medication administered via a pressurised aerosol, breath actuated aerosol, nebuliser or dry powder device

Question 24

Advantages and Disadvantages of inhalation?

Answer 24

Advantages

◦Drug delivered directly to site of action

◦Little systemic absorption (direct/specific)

◦Rapid effect

◦Small doses used

◦Reduced adverse effects

Disadvantages

◦Patient education is essential

Question 25

Nanoparticle based drug delivery

Answer 25

• Precise location
• More effective & reduce the chances of possible side-effects.
• Nanocarriers- Nanoparticles,Nanotubule,Nanoshell

Question 26

(Sub/Per)cutaneous

Answer 26

• Cutaneous relates to or affects the skin.
• Subcutaneous refers to being below the skin (as in a penetrating injury, injection or intravenous line).
• Percutaneous refers to being passed, done or effected through the skin. For example, some materials pass through exposed skin, causing poisoning.