Drug Formulation And Absorption Flashcards
Formulation is the process?
In which different chemical substances, including the active drug, are combined to produce a final medicinal product
Active ingredient is?
Any component of a drug product intended to furnish pharmacological activity
2 examples of how drug formulation and absorption are linked
Heparin and low Molecular weight heparin
Immediate and modified release morphine
Describe heparin vs low molecular weight heparin
Heparin= naturally occurring molecule
Low molecular weight heparin is a shorter molecule produced by fractionation of heparin
= physio-chemical difference - 2 different active ingredients
Immediate vs modified release morphine
Active ingredient (morphine) is identical to immediate release
In controlled release preparations morphine is absorbed e.g. Onto hydrophilic polymer
This is a modification information to alter the rate of absorption
Drugs may move across phospholipid bilayer how?
in terms of transport
Active transport
Facilitative transport
Pinocytosis
Passive diffusion
Weak acids are proton donators or acceptors?
Proton donators
Weak bases are proton donators or acceptors?
Proton acceptors
For a weak acid, if the ph is below its pka will more of the molecule be ionised or unionised?
Unionised
For a weak base if the ph is below the pka, will move of the molecule be ionised or unionised?
Ionised
pka is?
The pH at which ionised and unionised concentrations are equal
Log 1=
O
Ka =
equation
(Proton acceptor) (H+) / proton donator
pH=
equation
Log( proton acceptor) / (proton donor) + pKa
Excipients
Everything else in the product that isn’t the active molecule
Example of excipients
Anti-adherents
Binders
Coating
Coloring, flavours and sweeteners
Disintegrates
Emulgents
Preservatives/antioxidants/buffers
Pathway of aspirin after being dissolved in the stomach
Some aspirin is absorbed by the stomach and enters the hepatic portal vein
Most of the aspirin will be absorbed by the small intestine
Aspirin will undergo first-pass metabolism in the liver
Eventually reaches systemic circulation
example of drug formulation affecting absorption
Modified release
Enteric coating
Modified release is designed to?
Deliver drug over a continuos period or delay absorption
Enteric coating
Coating that prevents dissolution, disintegration in the stomach
Why might enteric coating delay release of drug to a specific area of GI tract to?
Prevent breakdown of drug in low pH of stomach
Deliver drug to specific site of action
Minimise adverse effects from direct gastric irritation
Example of drug formulated by enteric coating
Omeprazole
Example of drug formulated to modified release
Morphine or isosorbide mononitrate
Example of Drug delivery systems
Buccal wafers
Solid gels can be implanted for slow and prolonged release (contraceptive)
Patches
Ointments
Example of patches
Fentanyl
Example of ointment
Chloramphenicol eye ointment
Example of solid gel implant for slow and prolonged release
Contraceptive
Example of buccal wafers
Ondansteron - dissolve in mouth
Method example of modified release
Drug in a gel matrix that swells on contact with water
pH for acid:
= pKa + log ( (A-) / (AH) )
pH for a base
= pKa + log ( (B) / (BH+) )
For a weak acid, if the pH is below its pKa then more of the molecule will be unionized/ ionised?
unioised
For a weak base, if the pH is below its pKa then more of the molecule will be unionized/ ionised?
ionised
