Drug delivery system Flashcards
3 factors affecting dosage regime/delivery sys we use
drug dose
frequency and timing of administration
Oral Medication are commonly used and absorption is via …
GI tract
Absorption is via the GI tract for these routes of administration
Buccal Sublingual
Oral
Rectal
Solutions and Suspensions: Absorption depends on …….. and is most rapid from the …….
- Gastric emptying
2. small intestine
Dispersions of coarse drug particles in a liquid phase
suspensions
dose can be containe din small vol
good for drugs which are insoluble unpalatable - better tolerated
Hydrogel polymer release sys given in high dose are intact slowly releasing the effect.
Modified controlled release tablets
most commonly used formulation
tabs and capsules
…… or tablet break down is the ……… in absorption
- Dissolution
2. rate limiting step
……… delays disintegration of the tablet until it reaches the small intestine
Enteric coating
Tablets are enteric coated to:
Protect the drug from stomach acid (Omeprazole)
Protect the stomach from the drug (Aspirin)
Maintains drug level within therapeutic range and reduce the need for frequent dosing
rate of abs reduced
high dose but released slowly over a period of time
Always use the SAME brand name for this!!!!!
Prolonged or delayed release formulations
Oral Preparations ◦Verapamil◦Diltiazem◦Isosorbide mononitrate◦Lithium◦CarbamazepineProblems with possible toxicityParenteral Preparations◦Intramuscular injections of flupenthixol or risperidoneSurgical Implants◦Progesterone contraception◦Testosterone
.Prolonged or delayed release formulations
synthesised inactive derivatives of an active drug which requires to be metabolically activated after administration
Prodrug
The advantages of using prodrugs are◦prolongation of duration of action◦avoidance of degradation of the drug in the gut
For drugs which have extensive pre-systemic or first pass metabolism
- small and dissolve slowly upon administration
Buccal and sublingual administration
Most common example is GTN
Drugs may be administered ……
◦to treat…….conditions such as proctitis ◦to achieve …… absorption (indomethacin)
Bypass pre-systemic metabolism
rectally
local
systemic
Administered as a suppository
…. administration when a drug has a short half-life, quick action and careful control of [plasma] required
IV
Drug - insoluble or oil formulation.Allows a more sustained duration of action up to months .Depot Injections contraceptive, neuroleptics
Intramuscular injection
A common route of administration
Easy to use and bypasses need for venous access
Used for insulin, heparin and narcotic analgesics
Subcutaneous Injection
Transdermal drug delivery sys
Percutaneous
Creams, ointments and skin patches
percutaneous
(transdermal)
drugs admin to skin - local effect (steroids) or systemic effect (HRT or nitroglycerin)
Release of a drug from a reservoir into the skin and then into the systemic circulation
controlled, sustained blood levels of the administered drug such as nicotine, nitroglycerin, opiates, HRT, contraception
Skin patches
Deliver drugs directly to the lung for local effect or to achieve a systemic effect I.e anaesthetics
Inhalation
Advantages◦Drug delivered directly to site of action◦Rapid effect◦Small doses used◦Little systemic absorption◦Reduced adverse effects`Disadvantages◦Patient education is essentia
It is a sub-cutaneous needleless injection used for mass inoculation
Dermojet (insulin injector/pin-prick blood check)
Drug as a solid pellet is implanted under the skin to provide uniform systemic effect .Eg:testosterone
Pellet implantation
