Liquid Dosage Forms

Question 1

how to increase solubility

Answer 1

using co-solvents like glycerol, alcohol, propylene glycol

surface active agents and complexation can also be used

Question 2

excipients in oral solutions

Answer 2

buffers, sweetening agents, viscosity enhancing agents

Question 3

what is minimum inhibitory concentration

Answer 3

concentration required to inhibit microbial growth

Question 4

factors affecting the efficacy of preservatives

Answer 4

pH, presence of micelles, presence of hydrophilic polymers

Question 5

presence of hydrophilic polymers

Answer 5

can decrease concentration of the preservative available due to chemical interaction with the dissolved polymer

Question 6

suspensions

Answer 6

unstable, leading to sedimentation, particle-particle interactions, caking
electrical properties of particle interactions determine stability

Question 7

what is DVLO theory

Answer 7

when a dispersed liquid medium with particles experiences electric repulsive and attractive forces

Question 8

what is caking

Answer 8

particles at the bottom of the container are compressed by those at the top, until they have sufficient everygy to overcome the primary maximum (repulsive forces) and particles are close enough to form an irriversible reaction - caking

Question 9

how to decrease sedimentation rate

Answer 9

reducing average particle diameter, increasing viscosity of vehicle

Question 10

what is flocculation

Answer 10

particles are no associated in deflocculated system
flocculation means particles associate and are not closely packed, so caking does not occur
partial or controlled flocculation is ideal

Question 11

what controls flocculation

Answer 11

the addition of electrolyte or charged surfactants that reduce zeta potential to allow flocs to form

Question 12

tests for o/w and w/o

Answer 12

miscibility test, staining test, conductivity test

Question 13

what is cracking

Answer 13

complete coalescene of the internal phase, resulting in separation of emulsion into two layers
may be due to incorrect emulsifying agents, incompatible excepients, temperature, microbes

Question 14

what is creaming

Answer 14

density difference between oil and water phases, involves either sedimentation or elevation of droplets of internal phase, producing a layer of concentrated emulsion at the top or bottom of container

Question 15

direct incorporation method of making suspensions

Answer 15

high speed mixing if suspension is flocculated

particle size can be decreased using a ball mill

Question 16

precipitation method of making suspensions

Answer 16

drug dissolved in vehicle, addition of counterion (forms insoluble salt), excipients dissolved in vehicle