Capsules Flashcards
What is a capsule?
Solid dosage form in which a drug substance is enclosed in either a hard or soft shell or container and is generally prepared from a suitable form of gelatin
What makes capsules more versatile compared to tablets in terms of their contents?
Dry powders, semi-solids and liquids that do not dissolve gelatin may be encapsulated in capsules
Is the disintegration of capsules a greater concern compared to tablets?
No, less of a concern in capsules vs. tablets
What are some advantages of capsules?
Mask the unpleasant taste, aroma, or appearance of a drug
Powders can be dispensed in an uncompressed form, allowing quicker drug dissolution and absorption.
For almost any administration route (oral, rectal, vaginal), capsules can be made quickly and inexpensively.
The number of products a patient uses can be reduced by combining several drugs into one capsule or unit.
Easier to swallow
Ability to alter release rate (different shells have different properties)
What are some disadvantages of capsules?
They are easily tampered with (although techniques exist to prevent and identify this)
Are subject to the effects of relative humidity and subsequent microbial decomposition (gelatin in the capsule is affected)
Some individuals find capsules hard to swallow, soft gels can overcome this
What is the composition of hard gelatin shells?
Gelatin
Plasticizer
Colourant
Water 12-16%
What are some variables in the design of hard gelatin shells?
Size
Shape
Closure type
What is gelatin?
It is a protein constituent of skin, white connective tissue, and bones of animals.
What are the types of gelatin used in capsules?
Two types:
Type A (pork skin gelatin):
This type of gelatin contributes plasticity and clarity
Derived mainly from pork skins by acid hydrolysis
Type B (bone gelatin):
Contributes firmness
Derived mainly from bones and animal skins via alkaline processing
Types A and B may be blended to obtain the desired characteristics or flexibility (change viscosity)
What is the difference between gelatin and vegetarian capsule shells?
Vegetarian capsules tend to be more expensive (used by people with dietary or religious restrictions). They also are darker and less clear compared to gelatin
What is a plasticizer?
This ingredient makes up 5% of the capsule and it used to reduce the rigidity of gelatin and increase the flexibility and softness of the capsule
In hard shell capsules, little or no plasticizer is added (less than 5%)
What dosage forms are hard shell capsules optimized for?
Powders, granules, or pellets
What dosage forms can be used in soft shell capsules?
Liquids, solids dispersed in oil, and solids
What is the benefit of adding colourants to capsules?
Identification (colour is the simplest and best method for quick identification)
Light protection (colour reflects both the amount and wavelength of light passing through the gelatin layer)
Esthetic effects (masks variations in the colour of contents, raises confidence of users)
What is the water content of hard gelatin capsules?
13-16%
Anytime there is water, we have to be mindful of contamination by microbes.
Desiccants are often added to containers that contain capsules to absorb additional moisture, preventing moisture from entering the capsules
Water is added to the formulation of capsules to allow for some moisture loss, otherwise they would be brittle by the time of administration
What sizes are commonly found among capsules?
Capsules are assigned numbers according to their sizes, with larger numbers referring to smaller capsules. Eight standard sizes are used in human medicine
Capsule sizes 0 and 1 are the most common, but 2-3 are also popular. Larger capsules are used in rectal and vaginal formulations
What is the shape of hard gelatin shells?
The basic shape is oblong; variations depend on the manufacturer
What is the significance of the closure of capsules?
To prevent separation of the cap from the body (locking mechanism)
To provide evidence of tampering (helps improve safety)
What is the significance of locking mechanisms in capsules?
They are a pair of matching locking rings formed in the capsule’s cap and body portions. They are engaged following filling and cannot be pulled apart without damaging the capsule (detection of tampering)
What are the different methods of sealing the two parts of a capsule?
Spot-welded: by means of a heated metal pin pressed against the cap, fusing it to the body
Banded: coloured molten gelatin is laid around the joint between the two capsule parts
What is the purpose of diluent ?
To increase bulk for the dosage form, act as a vehicle, and improve content uniformity
Imparts cohesive property to the powder mixture to assist transferring the powder blend to the capsule bodies
Ex. Lactose, microcrystalline cellulose, starch
What is the purpose of disintegrants?
They assist in the break up of the powder mass/granules and help in distributing the drug throughout the stomach
Ex. Pre-gelatinized starch, croscarmellose, and sodium starch glycolate
What is the purpose of lubricant and glidants?
They improve fluidity and flow of powders
Decrease sticking of powders to metal surfaces
Reduces friction on surfaces in contact with powder
Ex. Calcium steerage, polyethylene glycol, talc
What is the purpose of wetting agents?
Often addd to facilitate the wetting of the drug substance by the GI fluids, thus enhancing dissolution
They also help with handling fluffy and light powders
Ex. Alcohol, water
What are the advantages of hard gelatin capsules?
Potential for rapid drug release (shells dissolve rapidly in 10-20 minutes due to less pressure applied during formulation)
Elegant, wide range of colours and possible opacity.
Ease of use (easy to swallow and tasteless) and portability
What are some disadvantages of hard gelatin capsules?
Limited number of shell suppliers
Generally more costly to produce than tablets
Do not use this dosage form for extremely soluble drugs
What are soft gelatin capsules?
They are characterized by a continuous, soft, globular gelatin shell which surrounds a liquid fill material (including suspensions, pasty materials or dry powders)
They are also formed, filled, and sealed in one operation
What is the composition of soft gelatin capsules?
Gelatin: 35-50%
Plasticizer: 15-30% (soften gelatin-based shell)
Colourant
Water: 30-40%
Preservative (added due to the high water content)
Is the shape of soft shell capsules standardized?
No, the shapes actually vary considerably
May be round, oval, oblong, tubes, etc. Compared to hard gelatin capsules, the shapes of SGCs are diverse
What are some of the requirements for fill materials in soft gelatin capsules?
Liquids encapsulated into soft gelatin capsules are limited to those that do not have an adverse effect on the gelatin shell.
The liquids contained within an SGC should not migrate through a capsule
Ex. Water (more than 5%), and low MW water soluble compounds & VOCs
pH should be between 2.5-7.5
What are the common types of soft gelatin capsules fill materials?
Pure liquid drugs
Solid drug dissolved or dispersed in vehicles (vegetable, mineral oils, and other water-miscible fluids)
Some solids (dry powders, granules, or pelletized materials
Are liquid filled soft gelatin capsules considered inaccurate and uniform with respect to their contents?
No, they are actually considered to be the most accurate
They are filled as a homogenous liquid vs. a mixture of powders which may not be so
They are also filled volumetrically with a syringe-like apparatus (volumetric filling of liquids is more accurate vs. volumetric filling of powders)
What are the advantages of soft gelatin capsules?
Permits liquid drugs to become easily portable
Adaptable (handles liquids, dispersions, and solids)
Patient preference (potential for increased compliance) like fish oils
Accurate dosage form as volumetrically filled (constant uniformity of +/- 1%)
Better bioavailability (fast dissolution)
Hard to tamper without being obvious
Should cotton balls be placed in bottles with soft gelatin capsules?
No, cotton balls act as desiccants and SGCs need to retain their water content
What can patients do help them swallow a capsule?
Try placing the capsule on the back of tongue before drinking a liquid
Place the capsule in warm water for a few seconds prior to taking. Allows capsule to slide over the mucous membranes easier
What are extemporaneously compounded capsules?
They are capsules that are produced personally by a pharmacist. It is done usually to tailor drug therapy for individual patients
How is a capsule size selected for extemporaneously compounded capsules?
The size selected for use is determined by the amount of material to be encapsulated. Usually a mixture of drug and diluent is used to fill a capsule.
How much materials should be prepared to make x number of capsules?
Make the mixture for x+2 capsules. Some powder will be lost during filling, so make sure you account for this loss
What is the procedure for blending the active ingredient and diluent?
Use geometric dilution by adding equivalent amounts of diluent to the total mass of the mixture. Do this until all diluent has been added into the final mixture.
What are the two methods of filling hard gelatin capsule shells?
Punch method
Hand operated machines
How are extemporaneously compounded capsules sealed?
Sealing:
Use a locking capsules or wet the outer edge of the body with a moist towel to soften the gelatin
How are extemporaneously compounded capsules cleaned?
Roll the capsules between the folds of a towel
Place the capsules into a container along with sodium carbonate, sugar, or sodium chloride, and gently roll the container
What is the drug content uniformity test?
We need to ensure all capsules contain relatively the same amount of drug.
Therefore the amount of drug must be within the range of 85-115% of the label claim for 9 of 10 dosages, with no unit outside the range of 75-125% of the label claim
What are physical stability tests?
Observe the capsules on a weekly basis for signs of discolouration
Record a description of the changes in appearance on a form for future reference
