depot injections Flashcards
benefits of long acting preparations
- maintain constant drug release
- less frequent administration
- more convenience
- enhance compliance
- local and/or systemic treatment
types of long acting preparations
- oily solution/suspension
- aqueous suspension and lipid emulsion
- rate controlling membrane
- bioerodable microsphere, microcapsule, implant
- in situ forming system
- liposomes, lipid based liquid crystal
- nanoparticles and PEGylated nanocarriers
- modified drug analogue
2 types of rate controlling membranes
- polymeric based membrane system
2. osmotic based membrane system
drugs used in oily solutions
contraceptives
hormones
antipsychotic agents
vehicles used in oily solutions
vegetable oils - castor oils
synthetic FA esters - isopropyl myristate, ethyl oleate
problems with using vegetable oils as vehicles for oily solutions
prone to heat and light oxidation
conisderations for oily solutions
vehicle viscosity
drug solubility
drug partition between oil and aqueous media
What effects the drug solubility?
- degree of drug loading
- vehicles with low dielectric constant (lipophilic drugs dissolve in these)
- lipophilic drugs have high partition coefficient (P) and distribution coefficient (D)
melting point vs solubility in oil
higher melting point means lower solubility in oil
drug solubility after addding a co-solvent
solubility enhanced with addition of a co-solvent
What is the best co-solvent to add?
water immiscible solvent
What QC tests should be done?
- patriculate contamination
- sterility and bacterial endotoxins with test for pyrogen
- uniformity of dosage form and content
- in vitro release profiles
Why use small particles?
to avoid rapid sedimentation
Why use lower interfacial area and tension for small particles?
to avoid clumps and caking
What can temperature variation cause?
change crystal habit and size
