Pharmacy tutorial 2 Flashcards
What are excipients?
An inactive substance that serves as the vehicle or medium for a drug or other active substance.
What can excipients be used for?
- To aid manufacture of the medicine
- Increase acceptability to the patient (improve flavour, fragrance or appearance)
- Improve chemical or biological stability (eg. capsule so it can reach further down the GI tract)
What is formulation?
The process of making a medicine containing a drug
List some formulations for oral route of administration
- Tablets
- Capsules
- Syrups
- Sublingual tablets
- Powders
List the advantages of the oral route of administration
- Allows self-medication
- Does not require rigorously sterile preparations
- Lower incidence of anaphylactic shock than IV
- There is capacity to prevent complete absorption
List the disadvantages of oral route of administration
- Innapropriate for some drugs (those altered by the pH of the stomach, or those that undergo first pass metabolism)
- Requires patient compliance
List the advantages of IV route of drug administration
- Rapid onset of action
- Avoids poor absorption from and destruction within the GI tract
List the disadvantages of IV drug administration
- Slow injection necessary to avoid toxic bolus
- Higher incidence of anaphylactic shock
- Complications are possible (embolism, phlebitis and pain)
List the advantages of inhalation drug administration
- Ideal for small molecules and gases
- Lungs have enormous SA
- Simple diffusion
List the disadvantages of inhalation drug administration
Possible localised effect within the lung
List the advantages of intramuscular drug administration
- High blood flow (into connective tissue reservoir in muscle block)
- Increased during exercised
- Enables depot therapy (prolongued absorption from a pellet, microcrystalline suspension or solution in oily vehicle)
List the disadvantages of intramuscular drug administration
Possible infection and nerve damage
List the advantages of subcutaneous injections
Local administration
List the disadvantages of subcutaneous injections
- Pain
- Abscess
- Tissue necrosis
List the advantages of percutaneous drug administration
- Local application and action (across the skin)
- Lipid soluble compounds diffuse rapidly
List the disadvantages of percutaneous drug administration
- Local irritation and skin reactions
- Alteration of skin structure
List some agents that could be used as excipients
- Lactose, glucose, starch
- Chalk (to make into a tablet large enough to pick up)
Define bioavalability
The amount of a drug contained in a medicine that enters the systemic circulation unchanged after administration of the drug
Why is bioavailability important?
- Allows a drug to reach the site of action and have effect
- Enables medication to be delivered systemically
When is bioavailability not important?
- When administering a drug locally
- When converting a drug to an active prodrug
How is bioavailability determined?
By comparing the areas under the plasma conc-time graph for the drug after IV administration and administration by the intended route
List the factors that affect bioavailability
- Physiochemical characteristics of the drug (ionisation)
- GI pH
- Passive/active transport
- GI motility
- Particle size of the drug
- Physiochemical interaction between the drug and gut contents (may be degraded by the microbiome)
List the available forms of aspirin
- Aspirin tablets
- Soluble aspirin
- Enteric coated aspirin
When would soluble aspirin be prefered?
- When in need of immediate pain relief
- Tablets are longer acting
