Drug Delivery

Question 1

How can drug formulation affect the effect of the drug?

Answer 1

Allow selective targeting of a tissue site or to avoid pre- or systemic metabolism, or to allow a 24 hour action

Treatment regime also needs to be tailored to a patients needs

Question 2

What determines the drug delivery system we use?

Answer 2

The dose of the drug to be given

The frequency of administration

The timing of administration

Question 3

What factors do we consider to determine the dose?

Answer 3

Renal function

Hepatic function

Consider age and weight

Consider disease to be treated

Consider drug toxicity

Give a starting dose and increase dose to achieve the desired effect

Question 4

Where does absorption take place?

Answer 4

Buccal Mucosa

Sublingual

Oral

Rectal

Question 5

What determines the speed of absorption of solutions and suspensions?

Answer 5

Gastric emptying - most rapid from the small intestine

Question 6

What is the benefit of Solutions and Suspensions?

Answer 6

Useful way to administer drugs to the young, elderly and patients with swallowing difficulties

Drugs given in this way are absorbed extremely rapidly

May be given via a naso-gastric or PEG tube

Question 7

What is a suspension?

Answer 7

Dispersions of coarse drug particles in a liquid phase

Question 8

What are suspensions useful for?

Answer 8

Drugs which are insoluble unpalatable as they are better tolerated

Question 9

What is the most commonly used formulation?

Answer 9

Tablets and capsules

Question 10

What is the rate limiting step for capsules and tablets?

Answer 10

Tablet breakdown (dissolution)

Question 11

What are the advantages of the tablets and capsules?

Answer 11

Convenience

Accuracy of dose

Reproducibility

Drug stability

Ease of mass production

Question 12

What is the effect of the enteric coated tablets?

Answer 12

Enteric coating delays disintegration of the tablet until it reaches the small intestine

Protect the drug from stomach acid Omeprazole

Protect the stomach from the drug (ulceration)
Aspirin

Question 13

What is the benefit of Prolonged or Delayed Release Formulations?

Answer 13

Most disorders required prolonged therapy

Maintains drug levels within a therapeutic range

Reduces the need for frequent dosing

Compliance is improved

Improved nursing and doctor compliance

This type of preparation contains more of the active drug but releases it more slowly over a prolonged period

Question 14

What are the advantages of prodrugs?

Answer 14

Prolongation of duration of action

Avoidance of degradation of the drug in the gut

Question 15

What is a prodrug reliant on?

Answer 15

Liver function - metabolism activates the drug

Question 16

What is Buccal and Sublingual Administration ideal for?

Answer 16

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

Question 17

How would you take sub-lingual drugs?

Answer 17

Sublingual tablets are small and dissolve slowly under the tongue or in the buccal cavity

Question 18

What is the rectal route useful for?

Answer 18

Useful in the young or old

Patients who are unable to swallow

Question 19

Why would you choose a rectal route?

Answer 19

Treat local conditions

Can achieve systemic absorption

Bypasses pre-systemic metabolism

Question 20

What is the vaginal route used for?

Answer 20

Local disease

Question 21

What are the advantages of injection based drug delivery?

Answer 21

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 22

When is intravenous administration used?

Answer 22

When: A rapid onset of action is required careful control of Plasma levels is required

A drug has a short half-life

Question 23

How may IV formulations be given?

Answer 23

Rapidly

Slowly to prevent toxic effects

Continuous infusion to ensure accurate control of blood levels especially when a drug has a narrow therapeutic index

Question 24

Describe what an Intramuscular Injection is?

Answer 24

An injection of the drug is given into the muscle mass

Question 25

Describe the type of solution given in intramuscular injection

Answer 25

The drug may insoluble or formulated in an oil base

Question 26

What is the benefit of intramuscular injection?

Answer 26

Allows a more sustained duration of action up to months BUT May be painful

Question 27

What are the advantages of subcutaneous injection?

Answer 27

Easy to use and bypasses need for venous access

Question 28

How does transdermal drug delivery enter the systemic circulation?

Answer 28

Adhesive patches containing the drug are applied on the skin

The drug crosses the skin surface by diffusion by percutaneous absorption

Question 29

What does transdermal drug delivery avoid?

Answer 29

Bypasses first-pass hepatic inactivation

Question 30

What is percutaneous drug administration?

Answer 30

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 31

What is the benefit of skin patches?

Answer 31

Possible to obtain controlled, sustained blood levels of the administered drug such as nicotine, nitroglycerin, opiates, HRT, contraception

Question 32

When are drugs administered by inhalation?

Answer 32

When there is a need to deliver drugs directly to the lung for local effect or to achieve a systemic effect I.e anaesthetics

Question 33

What are the advantages of inhalation?

Answer 33

Drug delivered directly to site of action

Rapid effect

Small doses used

Little systemic absorption

Reduced adverse effects

Question 34

What are the disadvantages of inhalation?

Answer 34

Patient education is essential

Question 35

How do monoclonal antibodies act?

Answer 35

Bind to cancer specific antigen and induce an immunological response to cancer cells

Question 36

What can Monoclonal antibodies be used to deliver?

Answer 36

Toxin, cytokine or other active drug§

Question 37

What is the purpose of liposomal drug delivery?

Answer 37

Altered pharmacokinetics results in reduced toxicity with enhanced efficiency

There is reduced distribution of drug to sensitive tissue

Question 38

What is another method of increasing the precision in targeting of a drug as well as reducing the toxicity?

Answer 38

Nanoparticle based drug delivery - makes the drug more effective and reduces the chances of possible side-effects

Question 39

What are nano erythrosomes and what are their applications?

Answer 39

Erythrocytes that can carry, proteins, enzymes and macromolecules

Used in the treatment of liver tumour, parasitic disease and enzyme disease

Question 40

What is the vector for the genetic transfer system involving the delivery of therapeutic genes to target cells?

Answer 40

Viruses