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Principles of Disease 16 > Drug Delivery Systems > Flashcards

Flashcards in Drug Delivery Systems Deck (20)

What are the three main factors considered when making up a dosage regime?

o The dose of the drug to be given
o The frequency of administration
o The timing of administration


What is the rate-limiting step in absorption of oral tablets?

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


What are the advantaged of giving drugs as pills or tablets?

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


What are enteric coated capsules?

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


Why are drugs enteric coated?

o Protect the drug from stomach acid
o Protect the stomach from the drug


Why are prolonged release formulations useful?

o Most disorders required prolonged therapy
o Maintains drug levels within a therapeutic range
o Reduces the need for frequent dosing
o Compliance is improved
o Improved nursing and doctor compliance


What are pro-drugs?

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


What are the advantages of pro-drugs?

o Prolongation of duration of action
o Avoidance of degradation of the drug in the gut


Why are buccal and sublingual drugs useful?

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


When would rectal suppositories, creams and solutions be useful?

Useful in the young or old
Patients unable to swallow
To treat local conditions such as proctitis
To achieve systemic absorption (indomethacin)
Bypass pre-systemic metabolism


Whats the benefit of injection based drug administration?

• 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


What are the three methods of injection based drug administration?

• Intramuscular
• Intradermal
• Subcutaneous


When are drugs given intravenously?

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


When are intramuscular injections usually used?

• Allows a more sustained duration of action up to months
• Depot injections of contraceptives and neuroleptics

Never if they have an issue with clotting!


What are the benefits of subcutaneous injection?

Easy to use and bypasses need for venous access


What are the benefits of transdermal delivery?

Bypasses first-pass hepatic inactivation
Easy to use
Good patient compliance


Describe the advantages of drug inhalation

o Drug delivered directly to site of action
o Rapid effect
o Small doses used
o Little systemic absorption
o Reduced adverse effects


What are the disadvantages of drug inhalation?

Patient education is essential


What are liposomes?

Liposomes are self-assembling closed colloidal structures composed of lipid bilayers and have a spherical shape in which an outer lipid bilayer surrounds a central aqueous space. Synthesised from cholesterol and can be used as drug delivery systems


What are the benefits of nanoparticle based drug delivery?

More specific drug targeting and delivery, which also reduces side effects and toxicity