Drug Administration

Question 1

Drug Concentration

Answer 1

Plasma concentration over time results from the ratio between absorption and degradation

Question 2

Intracranial (i.c.) and Intracerebroventricular (i.c.v) Administration:

Answer 2

• Administered directly into brain region (i.c) or into ventricles containing cerebral spinal fluid to carry drug throughout brain (i.c.v)
• Not systemic, not concerned with blood concentration
• Often used in experimental settings
Very high peak

Question 3

Oral Administration (p.o)

Answer 3

• Drug administered through tablets, pills, liquid
• Must dissolve in stomach fluid and pass through stomach wall, or be absorbed through the small intestine
• Must be resistant to stomach acid and digestion
• Peak is much small because some of the drug has already been metabolized by the time it reaches the blood stream
• Food in stomach causes delayed absorption
Relatively cheap, easy, and safe (less chance of an overdose)

Question 4

First Pass Effect:

Answer 4

• All drugs taken orally first pass through the liver, which contains lots of enzymes
  
  • Causes degradation of drugs, many drugs will not get the chance to reach the blood stream before it is metabolized by the liver

Question 5

Intravenous (i.v) Administration:

Answer 5

• Goes directly into the blood, very quick onset
• Most rapid effect
High risk of abuse and overdose

Question 6

Intramuscular (i.m) Administration:

Answer 6

• Slower, but absorbs more than IV administration
  
  • Needs to move through muscle cells, blood flow in area increases absorption
  • Drugs suspended in oil results in slower, sustained absorption (cannabis oil can result in the drug staying in your system for a very long time)

Question 7

Subcutaneous (s.c) Administration:

Answer 7

• Administered just below the skin
  
  • Absorption depends on blood flow to site
  • Slow and steady
  • Has to absorb through several layers of skin
  • No sharp peak, overall blood concentration lower because of metabolism

Question 8

Inhalation:

Answer 8

• Very rapid absorption
• Very rapid effect, blood from capillaries of lungs goes straight to the brain without returning to the heart first
Similar function to IV and IM

Question 9

Intraperitoneal (i.p.) Administration:

Answer 9

• Common in lab animals, rare for human
• Injection into peritoneal cavity (space surrounding abdominal organs)
• Convenient, relatively quick absorption
Function of peak concentration varies depending on injection location