The breakdown of tablets or capsules into small fragments is known as disintegration.The process in which tablets or capsules when coming in contact with fluid are converted into small fragments which pass through the sieve number 10 or 2.0±0.2 mm sieve leaving behind no hard mass.
- A disintegration test is performed
- in-vitro to ensure that after taking medicine it will release active pharmaceutical ingredients in the stomach and will be absorbed to give pharmacological effect.
- A disintegration test is performed to check whether tablets are not too hard so that when we take them, they do not dissolve in the stomach.
- In other words, we perform disintegration tests to ensure the bioavailability of drugs.
- Meaning our dosage form, mainly tablets and capsules, should be designed in such a way that after going into the stomach it should easily release the drug.
Relation Between Disintegration, Dissolution & Bioavailability
If tablet disintegration time is long its dissolution profile will be low and bioavailability will also be low.
In other words the amount of drug release in case of prolonged disintegration time is poor or slow.
- Suppose we have an uncoated tablet product whose disintegration time is 20 minutes and its dissolution profile is 65% and both the results are not compliant with our standard requirements.
- So we will make some adjustments in our formulation or tablet hardness to reduce disintegration time.
- Suppose after adjustments the tablet disintegrates within 10 minutes so its dissolution profile will also be improved, suppose 80%.
Factors Affecting Disintegration
Following are the main factors that that may affect the tablet disintegration,
- Amount Of Binder
- Amount of Disintegrants
- Granules Quality
- Tablet Hardness
Amount Of Binder
- Binders are one of the most important excipients which are used for tablet manufacturing.
- Binders along with solvents convert powders into granules and give strength to the granules.
- If the amount of binders in formulations is too high it will create very strong bondings and granules produced will be hard and difficult to disintegrate.
- Hard granules take more time to dissolve so our disintegration time will be prolonged and test results may not comply with specification and we may have to repeat the test after some adjustments.
- So the amount of binder and solvent used during wet granulation are selected very carefully.
Amount of Disintegrants
- Disintegrants are the excipients that are used to enhance the disintegration process or in other words disintegrants counter the effect of binders.
- As we know binders give strength to the granules, the disintegrants are used to break the bondings and convert tablets into granules and granules into powders to release the API.
- Disintegrants when come in contact with fluid,they swell or take water by capillary action and break the tablets or granules into small fragments.
- Along with disintegrants, the superdisintegrants are also used.
- The main difference between disintegrants and super disintegrants is that super disintegrants give fast and rapid effect at low concentrations.
- If granules produced are large and are sieved through a large mesh they will take more time to disintegrate so a proper sieve should be selected to produce optimum size granules.
- Tablet hardness and disintegration time are directly proportional, meaning the harder the tablet, the more time is required for its disintegration.
- So tablet hardness is kept optimum after conducting trials during product development to ensure the best results that comply with specifications.
The apparatus used for disintegration testing is known as a basket rack assembly.Two types of basket rack assembly are available which are as follow,
- Type A
- It is the most commonly used apparatus and it has 6 glass tubes.
- Type B
- It is used for large size tablets and capsules and it has 3 glass tubes.
Components Of Basket Rack Assembly
Basket rack assembly consists of following,
- Moving Shaft
- Glass Beaker
- Glass Water Bath
- The basket is the main component of basket rack assembly and it consists of 6 glass tubes.
- Glass tubes are hollow from the upper and lower sides.
- The length of Each glass tube is 75-80mm.
- One tablet or one capsule is placed inside each glass tube.
- On the lower side, a SS wire mesh of 10 number or 2±0.2mm is attached.
- The upper side of the basket has a long rod that is used to hang the basket with a moving shaft.
- 6 Disks are available for basket rack assembly.
- Thickness of each disk varies from 9.35 -9.65 mm.
- Each disk is made of transparent plastic having 1.18-1.2 specific gravity
- Each disk has 5 holes equally spaced from each other.
- Each disk can be placed in each tube after the addition of a tablet.
- Disks prevent the floating of tablets during up and down movements of the basket in the water beaker.
- Disks are used according to the specifications mentioned in the individual monograph.
- The shaft is used to move the basket up and down in the fluid beaker.
- The shaft of the basket rack assembly is attached with a motor.
- The frequency of shaft is 29-32 cycles per minute.
- A glass beaker of 1000 ml is used for basket rack assembly.
- The height of the glass beaker ranges from 138-160mm.
- Immersion Fluid is added up to 900 ml to the beaker.
- The temperature of the fluid is kept at 37±2 °C.
Glass Water Bath/Reservoir
- Immersion Fluid in the beaker is not directly heated, rather a glass reservoir is used as a water bath to keep the temperature of immersion fluid in the beaker at 37±2°C.
- HMI or human-machine interface is a control panel with a touch screen or buttons to control different parameters like temperature, shaft movement.
- It also has a timer to display the time.
- Take 6 tablets from a batch for which we want to check the disintegration time.
- Add immersion fluid in the beaker up to the level of 900 ml and bring its temperature up to 37±2 °C.
- When the desired temperature is displayed on HMI then add one tablet in each tube so we add 6 tablets in 6 tubes.
- The disks are used according to the description in the individual monograph.
- The basket is attached to the moving shaft.
- Press the start button to move the basket down in the beaker and then up.
- During the downward stroke, the wire mesh should descend NLT 25 mm from the bottom of the beaker.
- During upward stroke wire mesh should remain 15 mm below the fluid level.
- During the upward and downward stroke in the beaker, the tablets are observed from the transparent wall of the beaker and tubes.
- In the case of color products If tablets are not visible through the glass walls then after some interval the apparatus is paused and tablets can be observed in baskets.
- The process is continued for the time until all tablets disintegrate leaving behind no hard mass.
- The test is considered pass if all the tablets disintegrate within the specified time as mentioned in monographs like core or uncoated tablets should disintegrate within 15 minutes, coated tablets within 30 minutes and sugar-coated tablets within 60 minute.
- If tablets do not disintegrate within a specified time then repeat the test with additional 12 tablets.
- The test is considered pass if 16 out of 18 tablets disintegrate within the specified time.
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