Drug Delivery Flashcards
How can drug formulation affect the effect of the drug?
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
What determines the drug delivery system we use?
The dose of the drug to be given
The frequency of administration
The timing of administration
What factors do we consider to determine the dose?
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
Where does absorption take place?
Buccal Mucosa
Sublingual
Oral
Rectal
What determines the speed of absorption of solutions and suspensions?
Gastric emptying - most rapid from the small intestine
What is the benefit of Solutions and Suspensions?
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
What is a suspension?
Dispersions of coarse drug particles in a liquid phase
What are suspensions useful for?
Drugs which are insoluble unpalatable as they are better tolerated
What is the most commonly used formulation?
Tablets and capsules
What is the rate limiting step for capsules and tablets?
Tablet breakdown (dissolution)
What are the advantages of the tablets and capsules?
Convenience
Accuracy of dose
Reproducibility
Drug stability
Ease of mass production
What is the effect of the enteric coated tablets?
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
What is the benefit of Prolonged or Delayed Release Formulations?
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
What are the advantages of prodrugs?
Prolongation of duration of action
Avoidance of degradation of the drug in the gut
What is a prodrug reliant on?
Liver function - metabolism activates the drug
What is Buccal and Sublingual Administration ideal for?
Ideal method for drugs which have extensive pre-systemic or first pass metabolism