Ointments Flashcards
What is an ointment?
Semi-solid dosage form, anhydrous with hydrophobic oily base, intended for external application to skin or mucous membrane
What are the types of ointment?
Hydrophobic
Water emulsifying
Hydrophilic
What are the basic component of an ointment?
Drug
Ointment base
What may the ointment also contain?
Solvent
Antioxidant
Emulsifying agent
What base is for hydrophobic ointment?
Hydrocarbon base
What base is for water emulsifying (W/O) ointment?
Absorption base
What base is for water emulsifying (O/W) ointment?
Water-removable base
What base is for hydrophilic ointment?
Water-soluble base
How does the drug incorporation work?
Dissolve directly in ointment base
Dissolve drug in suitable solvent
Then incorporate solution into ointment base
Levigate solid drug into ointment base to disperse evenly, with geometric dilution
What is rancidification?
Oxidative chain reaction mediated by free radicals
= change organoleptic properties due to chemical decomposition
When is rancidification present?
Oxygen-containing fats + oils derived from animals or plants
What does antioxidant do?
Prevents rancidification of formulation components
Deplete free radicals
What are the two types of penetration enhancer?
Chemical = doesn’t require auxiliary equipment
Physical = require
What are examples of physical enhancement?
Microneedles
Laser ablation
Thermal ablation
What are ideal drug properties for percutaneous delivery?
Low relative molecular mass
Moderate lipophilicity
Low effective dose
How does chemical penetration enhancers enhance skin permeability?
Increase drug partitioning + diffusivity
What is a lipid-protein partitioning theory?
CPE mechanism of action
Lipid = disrupting stratum corneum lipids = increase diffusivity for lipophilic drugs
Protein = altering stratum corneum proteins = increase diffusivity for hydrophilic drugs
Partitioning = enhancing drug partitioning from formulation into skin = increasing partitioning
What are the ideal properties of penetration enhancers?
Chemically inert + non-toxic
Transient, reversible + selective penetration enhancement effect
