Medical pharmacology – Chapter 4 – modes of administration of
drugs
Administration of drugs lead to effects
1. Systemic effect; require circulation system to transport the drug
a. Intravascular administration: after systemic administration, resorption of
the drug into the circulation is required
2. Local effect; do not require circulation system to transport the drug
Mode of administration:
1. Enteral administration: involve the digestive tract
2. Parenteral administration: do not involve the digestive tract
Main route of drug administration
Per os, by mouth
o Oral (swallowed)
o Sublingual (under the tongue)
o Buccal (in the check pouch)
Injection
o IV; intravenous
o IM; intramuscular
o SC; subcutaneous
o IA; intraarterial
o Intrathecal; into subarachnoid space
Pulmonary
Rectal
Topical
Drugs from gastrointestinal tract (mouth, stomach, intestine, rectum), skin and lungs
– epithelium barrier – interstitium – capillary (with subcutaneous and intramuscular
site)– tissues and organs
Enteral administration
Most common route is oral administration (per os, p.o.).
The stomach
pH 1-2 which is beneficial for resorption of acidic drugs
total resorption-surface is smaller than in the small intestine. So resorption
from small intestine is quantitatively more important
resorption from stomach is unpredictable (e.g. depending on nature of
ingested food (fat or carbohydrate rich) or affected by physical activity)
administration on empty stomach with lot of water guarantees fast passage of
the compound to small intestine = fast resorption
The small intestine
total resorption-surface is big
duodenal pH is 4-5 more distally in the small intestine the pH becomes pH
neutral to slightly alkaline
passage of substances takes hours this is favourable for resorption
drugs
Administration of drugs lead to effects
1. Systemic effect; require circulation system to transport the drug
a. Intravascular administration: after systemic administration, resorption of
the drug into the circulation is required
2. Local effect; do not require circulation system to transport the drug
Mode of administration:
1. Enteral administration: involve the digestive tract
2. Parenteral administration: do not involve the digestive tract
Main route of drug administration
Per os, by mouth
o Oral (swallowed)
o Sublingual (under the tongue)
o Buccal (in the check pouch)
Injection
o IV; intravenous
o IM; intramuscular
o SC; subcutaneous
o IA; intraarterial
o Intrathecal; into subarachnoid space
Pulmonary
Rectal
Topical
Drugs from gastrointestinal tract (mouth, stomach, intestine, rectum), skin and lungs
– epithelium barrier – interstitium – capillary (with subcutaneous and intramuscular
site)– tissues and organs
Enteral administration
Most common route is oral administration (per os, p.o.).
The stomach
pH 1-2 which is beneficial for resorption of acidic drugs
total resorption-surface is smaller than in the small intestine. So resorption
from small intestine is quantitatively more important
resorption from stomach is unpredictable (e.g. depending on nature of
ingested food (fat or carbohydrate rich) or affected by physical activity)
administration on empty stomach with lot of water guarantees fast passage of
the compound to small intestine = fast resorption
The small intestine
total resorption-surface is big
duodenal pH is 4-5 more distally in the small intestine the pH becomes pH
neutral to slightly alkaline
passage of substances takes hours this is favourable for resorption
