Polymer 7: Soft Capsules

Question 1

Define what a soft capsule is?

Answer 1

1. Consists of a liquid or semi solid matrix
2. Sealed inside a one piece flexible gelatin shell
3. May have several shapes and sizes

Question 2

What makes gelatin soft?

Answer 2

1. Contains plasticiser (usually glycerol or propylene glycerol)
2. Water, preservatives and dyes

Question 3

Describe soft gel components?

Answer 3

1. Shell:
   - Gelatin
   - Plasticiser
   - Water
2. Optional enteric or delayed releasing coating
3. Fill:
   - Solution or suspension of drug
   - Vehicle: water or oil miscible

Question 4

What is the typical composition of a soft gel?

Answer 4

1. Gelatin (35 to 45%)
2. Plasticiser (glycerin, sorbitol, PEG) (15 to 25%)
3. Water (40%)
4. Dye and pigment may be needed
5. Opacifier as needed
6. Other (flavour and sugar may be needed)
7. Preservatives are not necessary

Question 5

What are the pharmaceutical applications of soft gels?

Answer 5

1. Oral dosage forms
2. Chewable soft gels
3. Suppositories
4. Topical Products

Question 6

What are the main advantages of a soft gel capsule?

Answer 6

1. Improved drug bioavailability (especially for poorly soluble drugs)
2. Formed, filled and sealed in one go in an automatic manner
3. Improved patient compliance (easy to swallow)
4. Dose is more uniform and precise (liquid form more precise than powder flow)
5. Safer manufacturing (no air bourne powders)
6. Drugs are protected against oxidation, photo degradation, hydrolysis in lipophilic systems

Question 7

How do you form soft capsules?

Answer 7

1. Molten mass of gelatin shell formulation at 60 degrees is fed into a reservoir
2. Two separate rotating casting drums
3. Form two spaced flat sheets or ribbons of gelatin
4. Flat ribbons are lubricated with coconut oil to prevent them sticking onto the machine
5. Brought together at convergent angle into nip of pair of rollers to form capsules

Question 8

What are the disadvantages of soft gel capsules?

Answer 8

1. Manufacturing softgels is a labour intensive process, complex and time consuming
2. Machines require to be specialised and it’s costly equipment
3. Manufacturing requires high quality gelatin
4. Organisations are then reluctant to set up their soft gel manufacturing organisations
5. Have to rely on other companies to manufacture the soft gel capsules for them

Question 9

What are the type of soft gel fill matrices?

Answer 9

1. Lipophillic liquids and oils (triglyceride oils)
2. Hydrophillic liquids
   - Aqueous solution of polymers
   - Ethanol (below 10%)
3. Self-emulsifying oil (pharmaceutical oil and surfactants)
4. Microemulsion and nano emulsion systems (lipid surfactant polar liquid)
5. Drug suspensions

Question 10

What are the specific requirements that are necessary for the formulation of a soft gel capsule?

Answer 10

1. Stable form of the drug
2. Fill vehicle that minimises the transfer of water from the shell into the fill
3. Excipients free from interactions with drug substance with each other
4. Excipients free impurities (e.g. aldehydes, peroxides) adversely effect the gelatin shell dissolution process
   - chemical stability of the drug substance
5. De-aeration of the fill formation to remove dissolved air (oxygen)
6. Plasticers minimise the transfer of components from the fill (ethyl alcohol) or into the fill (oxygen, moisture)
7. Inert environment during manufacturing
8. Appropriate storage conditions (container closure, temperature, relative humiditiy)
9. Moderate drying conditions

Question 11

What are the pharmacopeia standards for capsules?

Answer 11

1. Uniformity of weight
2. Content of API
3. Disintergration test
4. Dissolution test

Question 12

What are the things you have to think about before choosing tablet or capsule?

Answer 12

1. Company policy
2. Competitor products
3. Equipment available
4. Required unit dose
5. Compression characteristics
6. Stability