Bioavailabilty Flashcards
What is bioavailability
The sufficient amount of concentration a drug must reach to work
What is absolute bioavailability
It measures how much the drug reaches the bloodstream when taken orally vs IV
What factors affect bioavailability
- pharmaceutical factors
- physiological factors
-route of administration
Define pharmaceutical factors
Physical properties of the drug
What are examples of pharmaceutical factors
Particle size, crystalline structure, salt form
What manufacturing variables affect bioavailability
-pharmaceutical ingredients
-special coatings (aspirin)
-nature and types of dosage form
- Dissolution and disintegration time
What patient related factors affect bioavailability
- physiological factors
- Interaction with food
Examples of physiological factors
-Ph of GI fluids
- gastric emptying rate
- intestinal motility
-age/sex
-first pass metabolism
What interactions affect bioavailability
-food
-fluid volume
-other drugs
What routes of administration affect bioavailability
IV
IM
SC
ORAL
TRANSDERMAL
RECTAL
What is the bioavailability level of IV
100%
What is the bioavailability level of IM
75-100%
What is the bioavailability level of Oral medication
5-100%
What is the bioavailability level of rectal
30-100%
What is the bioavailability level of transdermal
80-100%
Why are ora drug less bioavailable
- active component doesn’t reach systemic circulation
What cause the active component not reaching the systemic cupirculation
-being destroyed in stomach/ intestines
-drug not being absorbed into GI tract due to it being removed by first pass metabolism
How does soulubilty affect bioavailability
Low soluble = low bioavailability
What is an excipient
Inactive component in drugs (may increase shelf life)
What do excipients do in relation to bioavailability
It affects dissolution and disintegration
What are the effects of food on bioavailability
Food may increase or decrease bioavailability
What medications bioavailability is reduce by food
Penicillin,erythromycin,thyroxine
When should medication bioavailability decreased by food be taken
30 minutes before
Why should some medications be take with food
They cause gastric symptoms when taken on an empty stomach
Absorption on what medications is delayed by food
Aspirin,paracetamol,dioxin and frusamide
Why would there be in increase of bioavailability in the presence of food
-When drug is highly soluble in fat
-When there is a delay in gastric emptying
- first pass metabolism is reduced
What happens if there’s a delay in gastric emptying
Time increase for poorly soluble drugs
