Excipients

Question 1

What are excipients?

Answer 1

Excipients control behaviour of dosage form

Question 2

What are the ideal properties of an excipient?

Answer 2

• Stable & Reproducible
• No unintended interaction with drug
• Pharmacaologically inert
• Give desired function
• Cost effective

Pharma grade - Comply with BP, PhEur or USP-NF

Question 3

What are the roles of excipients?

Answer 3

• Aid in the processing of the drug delivery system during its
manufacture

• Protect, support, or enhance stability, bioavailability, or
patient acceptability,

• Assist in product identification, and enhance any attribute of
the overall safety

• Assist in the effectiveness and/or delivery of the drug in use

• Assist in maintaining the integrity of the drug product during
storage

Question 4

What are some adverse effects of excipients?

Answer 4

• Glucose and Sucrose: Obesity and tooth decay if taken orally
• Benzyl Alcohol: A gasping syndrome in neonates
• Ethanol: CNS effects
• Polyoxyl castor oils: Severe anaphylactoid reactions

Question 5

Describe Diluents or bulking agent excipients

Answer 5

• added to make adequate sized tablet, handling
• Lactose (α-lactose monohydrate) –
• pleasant taste
• good solubility/dissolution
• low hygroscopicity
• Inert
• Spray dried lactose – used for direct compression (DC)
• Microcrystalline cellulose also good for DC
• Mannitol for chewable tablets

Question 6

Describe lubricant excipients used in tablets?

Answer 6

• Prevent powder/metal adherence – ensure smooth ejection
from die
• Enhance flow properties
• Magnesium stearate (up to 1 % w/w), hydrophobic
• Prolong disintegration time, reduce drug dissolution, reduce
tablet strength
• Sodium stearyl fumarate – hydrophilic

Question 7

Describe Binding agent excipients used in tablets?

Answer 7

• Adhesives to bind particles together during granulation
• Either added as dry powder during dry granulation or as a
solution for wet granulation
• Starch
• Polyvinylpyrrolidone (PVP)

Question 8

Describe Glidant excipients used in tablets?

Answer 8

• Improve flow of powders or granules
• Reduce interparticulate friction – smooth surface irregularities
• Colloidal silica

Question 9

Describe the disintegrating agents excipients used in tablets?

Answer 9

• Cause tablet to disintegrate – increases surface area
• Swell in contact with water – burst open tablet e.g. starch, croscarmellose sodium (known as a ‘superdisintegrant’)
• Some work by capillary action, drawing liquid up through pores which
disrupts bonds between particles e.g. pregelatinised starch
• Lyophilised tablets disintegrate with 5 s (orodispersible tablets), mainly
sucrose

Question 10

Describe the coating excipients used in tablets

Answer 10

• Film or sugar coat
• Enteric coatings e.g. cellulose acetate phthallate, or polymers (Eudragits)
• Polymers for M/R release e.g. HPMC (hydroxypropylmethyl cellulose),
xanthan gum

Question 11

Describe the water excipient use in liquid preparations

Answer 11

• Most widely used – physiologically non-toxic and compatible
• Good at dissolving ingredients
• BUT – supports microbiological growth and care with drugs
prone to hydrolysis

Question 12

Describe the water excipient use in liquid preparations

Answer 12

• Most widely used – physiologically non-toxic and compatible
• Good at dissolving ingredients
• BUT – supports microbiological growth and care with drugs
prone to hydrolysis

Question 13

Describe the water miscible co-solvents excipients used for liquid preparations

Answer 13

• Enhance solubility, taste and stability
• Propylene glycol, glycerol, ethano

Question 14

Describe the buffer excipients used for liquid preparations

Answer 14

• Control pH to enable physiological compatibility, microbial
and chemical stability and solubility (or insolubility if taste is
an issue)

Question 15

Describe the antimicrobial agent excipients used for liquid preparations

Answer 15

• Preservatives – prevent growth of opportunistic microbes
(from excipients or externally introduced)

Question 16

Describe the anti-oxidant excipients used for liquid preparations

Answer 16

• Control oxidation of drug, preservative, other excipients
• Concentration decreases with time since they oxidise first

Question 17

Describe the wetting agent excipients used for liquid preparations

Answer 17

• Decrease interfacial tension
• Surface active agents (e.g. Cetrimide, SLS), hydrophilic colloids
(e.g cellulose derivatives, tragacanth – also act as suspending
agents)

Question 18

Describe the antifoaming agent excipients used for liquid preparations

Answer 18

• Simeticone

Question 19

Describe the thickening agent excipients used for liquid preparations

Answer 19

• Stabilise suspensions – give high viscosity, often thixotropic
• methylcellulose

Question 20

Describe the sweetening agent excipient used for liquid preparations

Answer 20

• Natural – sucrose
• Artificial – saccharin

Question 21

Describe the flavouring agent excipient used for liquid preparations

Answer 21

• Natural – peppermint
• Artificial – butterscotch

Question 22

Describe the humectant excipients used for liquid preparations

Answer 22

• Hygroscopic excipients for external preparations (suspensions,
emulsions) e.g. glycerol, PEGs
• Reduce evaporation of water/aqueous vehicle – prevents
drying after application and during product life

Question 23

Describe Dyes and flavouring agent excipient used for tablet excipients

Answer 23

• dyed for identification