AP - Drug Product Design Considerations Flashcards
What is a drug substance?
The API e.g. aspirin
What is a drug product?
The final formulation that is being administered to the patient. It is the most suitable dosage form for delivering the drug.
Name one formulation characterisation test.
- Hardness
- Disintegration profile
- Dissolution
- Friability
- Wettability
Name one drug substance characterisation test.
- pKa
- Solubility
- Stability
- Log P
What is the most common dosage form for transdermal drug delivery?
Patches
Define transdermal drug delivery.
Transdermal drug delivery systems facilitate the passage of therapeutic quantities of the drug substances through the skin and into the general circulation to elicit their systemic effect.
In order for transdermal drug delivery to be effective, what is necessary?
Need to have enough concentration to go into the body and through the circulatory system in order to give a therapeutic effect e.g. HRT, contraception
Define topic drug delivery
Topical drug delivery systems are designed to deliver the drug INTO the skin for treating dermal disorders, with the skin as the target organ.
What is the difference between transdermal and topical drug delivery?
Transdermal goes into systemic circulation. Topical does not go into systemic circulation at all; it only has a local effect.
Average area of skin?
1.6 to 1.8m^2
How many layers are there in the skin?
Three.
What is the outermost layer and what is it’s function?
Epidermis.
First barrier - will prevent anything to go into systemic circulation.
Impermeable.
Protective.
Main barrier that decided if the drug even gets in.
What is the layer beneath the epidermis?
Dermis.
What is the layer beneath the dermis?
Adipose tissue (fat layer)
Why do you need to focus on cosmetic appeal?
It is visible, therefore not affect compliance in any way.
Advantages of formulation characteristics?
- Ease of manufacture
- Ease of use by patient
- Cosmetically elegant and appealing products
Disadvantages of formulation characteristics?
- Dosage control can be difficult (how much is ‘finger size’) –> this is not enough to cause really bad adverse side effects though
- Not all drugs can be delivered by this route (because absorption is very limited
- Amount of drug available for systemic action is limited due to physicochemical parameters of the drug e.g. Log P (lipophilocity) , pKa (ionisability), solubility
What are some pre formulation information you require?
- Identification and chemical info (NMR, mass spec)
- Validated analytical method (HPLC, GLC, UPLC) - to quantify how much of the drug is present in the sample
- Solubility:
a) aqueous - water/ ethanol etc
b) non aqueous - fats/ oils/ liquid paraffin/ waxes - Stability - is it stable? as a powder? accelerated stability testing. Is it stable in: oxygen, light, heat
- Toxicity
- Physicochemical parameters
a) Melting point (change in chemical structure will show)
b) pKa
c) Log P
d) partical size
Name a few topical and transdermal formulations
Ointments Creams Pastes Gels Lotions Solutions Aerosols Patches Oils Lacquers Powders
What excipients are commonly used in a solvent?
Water Ethanol Propylene glycol IPP IPM
What excipients are commonly used in a formulation base (usually gel or matrix)
WSP
Hard paraffin
Carbomer
Cellulose (gel mix)
What excipients are commonly used in an antioxidant? (if the drug is susceptible to oxidation in light, oxygen etc)
Vitamin E
Ascorbic acid
Propyl gallate
What excipients are commonly used in a metal chelator?
EDTA
What excipients are commonly used in preservatives?
Methyl and propyl paraben
benzalkonium chloride
What excipients are commonly used for skin penetration enhancers?
Ethanol Propylene glycol Glycofurol Miglyol IPP IPM
What is the excipient EDTA used for?
Metal chelator
What are the excipients water, ethanol, propylene glycol, IPP, IPM used for?
Solvent
What is the excipient propyl gallate used for?
Antioxidant
What is the excipient carbomer used for?
Formulation base
What are the excipients methyl paraben, propyl paraben and benzalkonium chloride used for?
Preservatives
What base does an ointment have?
Hydrophobic/ oleaginous base.