Pharmacology; Formulations, Routes of Administration and Doses

Question 1

Define formulation

Answer 1

Formulation is the process in which different chemical substances (excipients), including the active drug, are combined to make a final medicinal product

Question 2

List the enteral modes of administration.

Answer 2

• Oral
• Sublingual
• Rectal

Question 3

List and describe the enteral formulations.

Answer 3

Tablets:
• Compressed form of preparation that contains 5-10% active drug
• 80% of fillers, binders, lubricants etc
• 10% of compounds that facilitate dissolution
* Dissolution time can be adjusted to achieve fast or sustained release

Capsule:
• A gelatinous envelope enclosing the active substance
They can be designed to delay the release of the active drug, or mediate local release throughout the GI tract

Question 4

List the parenteral modes of administration (8

Answer 4

• Intravenous
• Intramuscular
• Intraperitoneal
• Intramedullary
• Intraspinal
• Subcutaneous
• Intra arterial
• Inhalation by nose or mouth

Question 5

List and describe the parenteral formulations of drugs.

Answer 5

Liquid:
• Stored in IV bags, cartridges
* Active drugs are combined with many excipients

Lyophilised:
• Dry, frozen powder form of a drugs where water is removed
• Used for transportation of a drug as it can be stored a t higher temps
* Stored in vials, cartridges

Question 6

List and describe the topical modes of administration

Answer 6

Transdermal:
• Drug is put in patches 
• The patch is put on the epidermis
• Drug is incorporated in a polymer which is bonded to an adhesive plaster
* Diffuses or absorbs into skin 

Conjunctiva:
* Applied in mucous membrane that covers the eye

Vaginal or urethral:
* Used for local effects

Question 7

List the topical formulations of drugs (5)

Answer 7

• Cream
• Ointment
• Gel
• Paste
• Powder

Question 8

List the advantages and disadvantages of oral administration

Answer 8

Advantages:
• Most commonly used as it is safe and painless
• Economical since sterilisation is not need
*No need of assistance

Disadvantages:
* Takes longer for the drug to react
• Polar drugs can’t be given as they are not absorbed FOR EXAMPLE streptomycin
• Drugs are destroyed by digestive juices
• 1st pass effect: destroyed in the liver before it can even reach systematic circulation
• Drugs can’t be given to unconscious patients
• Bad test or bad smell
Drugs can’t be given during vomiting

Question 9

List the advantages and disadvantages of sublingual administration

Answer 9

Advantages:
• Drug is placed under the tongue, or crushed in mouth and placed around buccal mucosa
• Quick onset of reaction
• Bypasses liver and thus the first pass effect
* Drug action can be terminated if side effects occur

Disadvantages:

• Distasteful
• Higher molecular weight drugs like INSULIN can’t be absorbed

Question 10

List the advantages and disadvantages of rectal administration

Answer 10

Advantages:

• Useful in instances of vomitting/nausea
• Bypasses 1st pass effect

Disadvantages:
• Invasive
• Absorption is irregular
* Chances of rectal inflammation

Question 11

List the advantages and disadvantages of intravenous administration

Answer 11

Advantages:
* Directly enters systematic circulation
• No 1st pass effect
• Quick onset of reaction
• Less dose is needed for results
• Can be given to unconscious patients/ those with nausea/vomitting
* Amount of drug can be controlled with an emergency

Disadvantages:
• Painful
• Aseptic conditions needed
• Can result in infection
• Need someone to administer it properly
• Risky, once injected it can't be recalled
• Damage around injection site
* Oily drugs can't be administered this way

Question 12

List the advantages and disadvantages of intraspinal administration

Answer 12

Advantages:
* Diagnostic imagining to visual spinal chord

Disadvantages:

• Strict, aseptic conditions needed
• High level of expertise needed

Question 13

List the advantages and disadvantages of intramuscular administration

Answer 13

Advantages:
* Absorption is predictable, less variable and rapid compared to oral route

Disadvantages:
• Needed perfect aseptic conditions
• Chances of abscess
• Chances of nerve damage/ paralysis of muscle
* Large volumes cannot be given

Question 14

List the advantages and disadvantages of intraperitoneal administration

Answer 14

Advantages:
* Rapid absorption due to large surface area

Disadvantages:

• Painful
• Risky

Question 15

Describe the cream topical formulation

Answer 15

Emulsion of oil and water in equal proportions. Penetrates outer layer of skin well

Question 16

Describe the ointment topical formulation

Answer 16

Combines 80% of oil and 20% water. Stops water loss

Question 17

Describe the gel topical formulation

Answer 17

Liquifies upon skin contact

Question 18

Describe the paste topical formulation

Answer 18

Oil, water and powder

Question 19

Describe the powder topical formulation

Answer 19

Particles

Question 20

List and describe the three new drug delivery systems

Answer 20

Liposomes:
* A small spherical sac of phospholipid molecules enclosing a water droplet, especially as formed artificially to carry drugs or other substances into the tissues.
• The polar region (hole) is good for storing drugs
* Used for targeted drug delivery through specific receptors

Nanoparticles:
• Can be made or naturally occuring
• Can cross any barrier because of small size
• Drug is connected to nanoparticle
* Are pH and temperature sensitive and can be activated this way

Computerised miniature pumps:
* Insulin pumps. They can measure blood glucose and will inject insulin based on a pre-calculated algorithim