Friability is one of the most important and simple tests which is performed for tablets to know how friable tablets are, meaning to estimate to what extent tablets can break when rotated in a drum to check the effect of attrition and tumbling.
The percentage of weight loss is called friability.
In other words weight loss of tablets is called friability and weight is lost when tablets are chipped or its edges are broken.
Other Names of Friability Test
- Drop Test
- Abrasion Test
- Attrition Resistance Test
- Friability test is done for uncoated or core tablets.
- Friability testing of Coated tablets is not required because coating gives strength to the tablets.
- The apparatus used for friability testing is known as Friabilator and the commonly used apparatus is Roche Friabilator.
- It has a drum made of synthetic transparent polymer driven by a motor.
- It rotates at the speed of 25±1 rpm.
- The drum is rotated for 4 minutes.
- The internal diameter of the drum ranges from 283-291 mm.
- An arch is installed in a chamber of drum by which tablets rise and fall inside the chamber.
- During rotation of the drum, the tablets fall from the height of 156±2 mm or 6 inches.
Types of Drums
Following three types of drums can be used which are given below,
- Roche Type
- Vankel Type
- Abrasion Drum
- This is a simple type of drum in which a single arch or curve is present.
- The drum has one chamber.
- It is used for single testing meaning one sample can be run at a time.
- This type of drum has a double or two curves or arches.
- The drum has two chambers.
- One arch is present on one side of the drum in one chamber and the other is present on the other side in the second chamber.
- It is used for double testing meaning two samples can be run at a time.
- This type of drum has many baffles attached to the sides walls of the drum
- This type of drum is used for those products which require extra mechanical stress.
Why To Perform Friability Testing?
It is a common question that why we need to check the tablet friability and the answer to this question is that we check friability to ensure that tablet will not cap,chip or break during
- Tablet Coating
- Tablet Blistering
- Tablet Transportation
- After compression the tablets should be strong enough to withstand the attrition and tumbling effect during rotation in the coating pan.
- When tablets are coated they are rotated in the pan for a long period and also strike with baffles and fall from a height so if tablets are weak they will break and chip during the coating operation.
- Due to this reasonable tablets should be of suitable hardness and strong enough to resist breakage.
- To ensure tablet strength the friability of tablets is checked during the compression operation.
- When it is ensured that tablets are not chipped, capped or broken in the friability testing and percentage weight loss is within limit then we start compression operation.
- This friability test before starting the actual tablet compression operation gives us confidence that tablets will not chip during the coating operation.
- Core tablets also face friction and rotation during tablet blistering by the feeding system of the blister machine so tablets should not be friable and remain intact during tablet blistering.
- Apart from tablet coating operation and blistering process the core tablets may chip or break during transportation.
- Transportation may be of two types, the first one is during shifting of tablets from one operation to another like after compression to the staging area and from staging to the coating area or in case of core tablets to the blistering area and after blistering to the packaging area or after packaging to the finish good store.
- During all these operations if the tablets are not strong enough they may break.
- The second type of transportation is its delivery from the pharmaceutical industry to the distributor or from the distributor to the pharmacies, during this, the product is handled by various persons for its loading and unloading and if the tablets are not strong enough they may break or chip.
- To prevent all the above-mentioned problems it is necessary to check the friability of the tablets before starting the actual compression operation.
- For this,after line clearance of compression operation we compress some tablets and deliver its sample to the QA department to perform hardness, friability and other tests and after passing all these parameters we start the actual compression operation.
How To Select Number Of Tablets?
It is a common question that how many tablets should be taken for a friability test?
The answer to this question is given as follow,
- If individual tablet weight is equal to or less than 650 mg then take as many tablets as close to get an average weight of 6.5 grams.
- If individual tablet weight is more than 650 milligrams then take 10 tablets for friability testing.
How To Perform a Friability Test?
- The tablets are selected according to the specifications of weight as mentioned above.
- After taking the required number of tablets, the tablets are de-dusted to remove any fine powder or loosely attach powder with the help of pharma compliant brush.
- After de-dusting the average weight of the tablets is checked on the weighing balance and this weight is known as initial weight or W1.
- The initial weight or W1 is noted and tablets are placed in the drum of the friabilator.
- On one side the drum has a glass opening to add tablets and it also has an arch which gives an attrition effect to the tablets.
- After placing tablets inside, the glass cover is closed and the rotation of the drum is turned on.
- The drum rotates for 4 minutes at a speed of 25 rpm meaning in 4 minutes it completes 100 rounds.
- After the completion of 4 minutes, the drum is stopped automatically and tablets are removed from the drum.
- After removing from the drum,tablets are physically checked for chipping or breaking and again weight is checked after dedusting and this weight is known as final weight or W2.
- Use the following formula to calculate the friability,
Initial weight (W1) – Final weight (W2) / Initial weight (W1) ×100
If results of weight loss are NMT 1% then our test is passed and if tablets are capped or chipped or results are more than 1 % then our test is failed.
- If our test is failed then we can repeat the test twice and the mean value of weight loss of three tests is determined.
- If the maximum mean of three values is not more than 1% then the test is considered a pass in most cases.
- After the friability,if the tablets are chipped or capped we can adjust the machine setting and can make changes in hardness and again a test is performed.
- If the machine setting does not solve the capping or chipping issue then we apply some moisture to the granules or can use a slugging method depending upon the formulation and practical experience.
Moisture Sensitive Products
- To perform the friability testing of moisture sensitive products the temperature and humidity of the area should be controlled before performing the test.
- Stages and Mechanism of Tablet Compression.
- History of compression machine.
- Reasons and remedies of tablet sticking and picking.
- Dust cups for compression machines.
- How to compress Bilayer tablets?