ABSORPTION Flashcards
(47 cards)
Absorption definition
Transfer of drug from site of administration to systemic circulation
Types of factors that can affect absorption
- Factors related to drug
- Factors related to patient
Examples of factors related to drug absorption
- Size of the drug
- Water and lipid solubility
- Ionization
- Nature of drug and its molecular weight
- Valency
- Preperation and dosage form
- Rate of disintegration
- Excipients
Drugs must be water/lipid soluble?
DRUGS MUST ME WATER AND LIPID SOLUBLE
Increasing lipid solubility, increases …..
Absorption
If the drug is insoluble in water it is …….
NOT absorbed
Lipid soluble drugs are ionized/non-ionized?
NON-IONIZED
Inorganic drugs have …….. molecular weight
SMALL
Organic drugs have …….. molecular weight
LARGE
Which iron ion is absorbed more?
Ferrous iron (Fe2+)»_space;»» Feric iron (Fe3+)
Dosage form:
Solution»_space; Suspension»_space; Tablets
………. has a rapid rate of disintegration
Paracetamol
……… has a slow rate of disintegration
Digoxin
Calcium carbonate decreases the absorption of ……..
tetracycline
Factors related to patient that affect drug absorption:
- Route of administration
- Absorbing surface
- Systemic circulation
- Specific factors
- Other drugs
Route of adminstration with decreasing absorption rate:
IV > IM > SC > Oral > skin
Surface area with descending absorption rate
Alveoli > Intestine >Stomach
Absorbing surface with decreasing vascularity:
Alveoli > Muscle > SC
When does systemic circulation have low absorption rate?
In shock or heart failures as blood flow to skin and muscles decreases
How to increase absorption of Vitamin B12
Increase secretions of intrinsic factors from the stomach
Effect of adrenaline on local anesthetics
Causes vasoconstriction so decreases absorption
Drugs that increase gastric emptying
Metoclopramide
Drugs that decrease gastric emptying
Atropine
Effect of metoclopramide on absorption rate
Metoclopramide increase gastric emptying so increase rate of absorption of drugs with rapid disintegration rate (paracetamol) and decrease rate of absorption of drugs with slow disintegration rate (digoxin)