Drug Delivery Systems Flashcards

1
Q

How can a drug delivery system be formulated?

A
  • to allow selective targeting of a tissue site
  • to avoid pre- or systemic metabolism
  • to allow a 24 hour action
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2
Q

What determines the drug delivery system we use?

A
  • the dose of the drug to be given
  • the frequency of administration
  • the timing of administration
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3
Q

What must be considered when choosing a dosage regime?

A
  • recommended dose
  • renal function
  • hepatic function
  • age and weight
  • disease
  • drug toxicity
  • starting dose
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4
Q

What is considered oral medication?

A
  • solutions
  • suspensions
  • capsules
  • tablets
  • modified release tablets
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5
Q

How are oral medications absorbed?

A

via the GI tract

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6
Q

How can oral medication be administered?

A
  • buccal
  • sublingual
  • oral
  • rectal
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7
Q

What are solutions and suspensions useful for?

A
  • young
  • old
  • patients with swallowing difficulties
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8
Q

How can solutions and suspensions also be given?

A

Via a naso-gastric or PEG tube

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9
Q

Describe the absorption of solutions/suspensions given via ng/PEG tube.

A
  • absorbed extremely rapidly

- most rapidly from the small intestine

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10
Q

What is absorption of solutions/suspensions dependent on?

A

Gastric emptying

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11
Q

What is a suspension?

A

Dispersions of coarse drug particles in a liquid phase which can be contained within a small volume

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12
Q

What are suspensions good for?

A

drugs which are insoluble unpalatable as they are better tolerated

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13
Q

What do oral delivery systems involve?

A

Use of various polymers and hydrogel based formulations

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14
Q

What is the rate limiting step in absorption of tablets?

A

Dissolution or tablet break down

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15
Q

What are the distinct advantages of tablets/capsules?

A
  • convenience
  • accuracy of dose
  • reproducibility
  • drug stability
  • ease of mass production
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16
Q

What does enteric coating on a tablet do?

A

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

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17
Q

Why are tablets enteric coated?

A
  • protect the drug from stomach acid i.e. omeprazole

- protect the stomach from the drug i.e. aspirin

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18
Q

Why are prolonged/ delayed release formulations useful? (5)

A
  • 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
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19
Q

How can the time course for a drug in the body be prolonged?

A
  • reducing the rate of drug absorption

- giving the drug in a form which has slower, but sustained release

20
Q

What are oral examples of prolonged/delayed release drugs?

A
  • verapamil
  • diltiazem
  • isosorbide mononitrate
  • lithium
  • carbamazepine
21
Q

What are parenteral preparation examples of prolonged/delayed release drugs?

A
  • IM injections
  • flupenthixol
  • risperidone
22
Q

What are surgical implant examples of prolonged/delayed release drugs?

A
  • progesterone contraception

- testosterone

23
Q

What are prodrugs?

A

Prodrugs are synthesised inactive derivatives of an active drug which requires to be metabolically activated after administration

24
Q

What are the advantages of using prodrugs?

A
  • prolongation of duration of action

- avoidance of degradation of the drug in the gut

25
Q

What is buccal/sublingual administration ideal for?

A

drugs which have extensive pre-systemic or first pass metabolism

26
Q

Why might a drug be administered rectally?

A
  • to treat local conditions such as proctitis

- to achieve systemic absorption (indomethacin)

27
Q

Does administration via the rectal route bypass pre-systemic metabolism?

A

yes

28
Q

What can be administered vaginally?

A
  • pessaries

- creams

29
Q

What does the injection based drug delivery system provide?

A

fast systemic effects bypassing first-pass metabolism

30
Q

When are drugs administered IV?

A
  • a rapid onset of action is required
  • careful control of plasma levels is required
  • a drug has a short half life
31
Q

IV formulations may be given…

A
  • rapidly
  • slowly to prevent toxic effects
  • continuous infusion to ensure accurate control of blood levels especially when a drug has a narrow therapeutic index
32
Q

What do IM injections allow?

A

a more sustained duration of action

33
Q

What are subcutaneous injections used for?

A
  • insulin
  • heparin
  • narcotic analgesics
34
Q

How does the transdermal drug delivery system work?

A
  • The drug crosses the skin surface by diffusion by percutaneous absorption and goes into systemic circulation
  • bypasses first-pass haptic inactivation
35
Q

What do skin patches allow?

A

The release of a drug from reservoir into the skin and then into the systemic circulation.

36
Q

How can inhaled drugs be delivered?

A
  • pressurised aerosol
  • breath actuated aerosol
  • nebuliser
  • dry powder device
37
Q

What are the advantages of inhalation?

A
  • drug delivered directly to site of action
  • rapid effect
  • small doses used
  • little systemic absorption
  • reduced adverse effects
38
Q

What is the major disadvantage of inhalation?

A

Patient education is essential

39
Q

Describe the action of monoclonal antibodies.

A

mAbs act directly when binding to a cancer specific antigen and induce immunological response to cancer cells

40
Q

Why have mAbs been modified?

A

For delivery of a toxin, cytokine or other active drug

41
Q

What do pre-clinical and clinical liposomal packed drugs exhibit?

A

reduced toxicities with enhanced efficiency

42
Q

What does nanotechnology allow in drug delivery systems?

A

The drug can be targeted to a precise location which would make the drug much more effective and reduce the chance of possible side-effects

43
Q

Name 3 nanocarriers?

A
  • nanoparticles
  • nantubule
  • nanoshell
44
Q

What are the advantages of nanoparticle based drug delivery?

A
  • more specific targeting and delivery

- reduction in toxicity while maintaining therapeutic efficiency

45
Q

What are nanoerythrosomes?

A
  • Resealed erythrocytes that can carry proteins, enzymes and macromolecules
  • Used in the treatment of liver tumour, parasitic disease and enzyme disease
46
Q

What is genetic transfer system in clinical trials for?

A
  • adenovirus

- HIV