depot injections

Question 1

benefits of long acting preparations

Answer 1

• maintain constant drug release
• less frequent administration
• more convenience
• enhance compliance
• local and/or systemic treatment

Question 2

types of long acting preparations

Answer 2

• 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

Question 3

2 types of rate controlling membranes

Answer 3

1. polymeric based membrane system

2. osmotic based membrane system

Question 4

drugs used in oily solutions

Answer 4

contraceptives
hormones
antipsychotic agents

Question 5

vehicles used in oily solutions

Answer 5

vegetable oils - castor oils

synthetic FA esters - isopropyl myristate, ethyl oleate

Question 6

problems with using vegetable oils as vehicles for oily solutions

Answer 6

prone to heat and light oxidation

Question 7

conisderations for oily solutions

Answer 7

vehicle viscosity
drug solubility
drug partition between oil and aqueous media

Question 8

What effects the drug solubility?

Answer 8

• 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)

Question 9

melting point vs solubility in oil

Answer 9

higher melting point means lower solubility in oil

Question 10

drug solubility after addding a co-solvent

Answer 10

solubility enhanced with addition of a co-solvent

Question 11

What is the best co-solvent to add?

Answer 11

water immiscible solvent

Question 12

What QC tests should be done?

Answer 12

• patriculate contamination
• sterility and bacterial endotoxins with test for pyrogen
• uniformity of dosage form and content
• in vitro release profiles

Question 13

Why use small particles?

Answer 13

to avoid rapid sedimentation

Question 14

Why use lower interfacial area and tension for small particles?

Answer 14

to avoid clumps and caking

Question 15

What can temperature variation cause?

Answer 15

change crystal habit and size

Question 16

What can concentrated suspension and irregular shape powder cause?

Answer 16

pain and irritation

Question 17

What does thixotropic flow allow for?

Answer 17

consistent dispensing/dosing

Question 18

What can water miscible organic solvent cause?

Answer 18

change solubility and can cause irritation

Question 19

What deflocculation should be suspension be?

Answer 19

patrially deflocculated

Question 20

What polymer is used in RCM (rate controll membrane) based implant?

Answer 20

polyethylene vinyl acetate

Question 21

What does a higher vinyl acetate content in RCM based implant lead to?

Answer 21

lower Tg of polymer

glass transitional temperature

Question 22

What is drug release based on in RCM based implant?

Answer 22

• SA of implant
• drug solubility in polymer
• concentration gradient
• membrane thickness

Question 23

What is D (distribution coefficient)?

Answer 23

solubility of the drug in the oily phase

high D - high drug solubility in oily phase

better parittioning of drug into oily phase rather then aqueous phase

inc D - inc oil solubility