Lecture 8.2: Drug Administration Flashcards
What is Pharmacology?
Science of drug action on biological systems
What is Pharmacodynamics?
It is what the drug does to the body
What is Pharmacokinetics?
It is what the body does to the drug
4 questions to be asked when prescribing drugs
- Is drug getting into patient?: Pharmaceutical process
- Is drug getting to site of action?: Pharmacokinetic
process - Is drug producing desired effect?: Pharmacodynamic
process - Is this translated to a therapeutic effect?: Therapeutic
process
What is a Drug?
A substance that changes a biological system by
interacting with it
What is a Medication?
A drug presented in a form intended for restoring or
preserving health
The drug (tablet) is mixed with other substances (excipients) to allow…? (4)
- Manufacturability
- Practicality of administration
- Control onset of action
- Control duration of action
What is a Disintegrant?
A substance that helps the tablet breakdown and dissolve in GI tract
What is a Binder?
A substance holding the tablet together
What is a Lubricant?
Substance that prevents “wear & tear” on tablet making equipment and facilitates removal from tablet moulds
What is a Diluent?
“Filler” providing extra volume and weight
What is the Process of making a Tablet? (6 Steps)
1) Active Ingredient + Excipients
2) Mixing and Granulation
3) Drying
4) Compression
5) Coating
6) Packaging
Film Coated Tablets
Core – contains drug & excipients
Film – non functional
Pros of Film Coated Tablets (6)
- Improve appearance
- Ease of swallowing
- Product stability – mechanical integrity
- Increased shelf life
- Taste masking
- Identification & trade marking
What is an Active Ingredient?
Chemical substance intended to provide the desired pharmacological effect
Modified Release Film Coatings
1) Delayed-Release (e.g. gastro-resistant/ enteric
coating)
2) Sustained / Extended-Release Coatings
Why might drugs have Delayed-Release (e.g. gastro-resistant/ enteric coating)?
- To protect the acid-labile drug substances from the
acidic pH of gastric acid - To prevent gastric ulceration due to irritation by
certain drugs such as aspirin nonsteroidal anti-
inflammatory compounds
Benefits of Sustained / Extended-Release Coatings (5)
- Reduced local adverse effects in the gastrointestinal
tract - Reduced adverse effects associated with peak blood
levels - Less fluctuation in blood levels across the course of
the day - Artificially extended half-life
- Convenience of dosing - improved compliance
What are some common sites of Intramuscular Injection? (4)
- Deltoid
- Gluteal
- Vastus lateralis
- Rectus femoris
What is a disadvantage of subcutaneous injection?
Absorption slower than via the intramuscular route
What drugs are subcutaneous injections better for?
Beneficial continuous absorption of a drug is required:
* Insulin
* Heparin
Name Types of Injections (6)
- Intravenous
- Intramuscular
- Subcutaneous
- Intraarticular
- Intraosseous
- Intrathecal
- Intravitreal
What is an Intrathecal Injection?
Direct injection of the drug into the CSF (cerebro-spinal fluid), circumvents blood brain barrier
What is an Intravitreal Injection?
In which the substance is delivered into the vitreous humor of the eye
What are Emollients?
Moisturising treatments applied directly to the skin to soothe and hydrate it
What is a topical steroid?
- Topical steroids are the topical forms of corticosteroids
Topical steroids are the most commonly prescribed topical medications for the treatment of rash, eczema, and dermatitis
Topical steroids have anti-inflammatory properties and are classified based on their skin vasoconstrictive abilities
Side-Effects of Topical Steroids (5)
- Skin thinning (atrophy) of time
- Stretch marks (striae)
- Easy bruising (purpura) and tearing of the skin
- Enlarged blood vessels (telangiectasia)
- Localised increased hair thickness and length (hypertrichosis)
How are Transdermal Medications administered?
“Patch” containing the drug is applied to the skin, it seeps out of the patch through the skin (at a predetermined rate) into the capillary bed
Advantages of administering drugs transdermally (4)
- Constant plasma concentrations of a drug
- Non-invasive
- Self-administered
- Simple (patient adherence)
Disadvantages of administering drugs transdermally ()
- Rashes/Irritation due to patch
- Drug absorption limited by skin permeability
- Cannot reach high concentrations in blood
- Ionic drugs cannot be administered via this route
- Lipophilic & Hydrophilic drugs need modifying
Why is the nasal route good for drug administration?
Nasal mucosa is very vascular and easily accessible, non-keratinised epithelium (high permeability)
What types of drugs is the nasal route good for?
Feasible for peptides: AHD, gonadotropin releasing hormone
What is the Therapeutic Ratio?
Maximum tolerated dose/Minimum effective dose
LD50/ED50
