Techniques used in the preparation of orodispersible tablets

1. TECHNIQUES USED IN THE PREPARATION OF
ORODISPERSIBLE TABLETS:
VARIOUS TECHNOLOGIES USED IN THE MANUFACTURE OF ORODISPERSIBLE TABLETS INCLUDE :
• Freeze-drying or lyophilization
• Tablet Molding
• Spray drying
• Sublimation
• Melt granulation
• Phase transition
• Direct compression
• Sugar Based Excipients
Presented by-
Arzoo Piruka
201703100210100
Maliba Pharmacy College

2. FREEZE-DRYING OR
LYOPHILIZATION

3. FREEZE-DRYING OR LYOPHILIZATION
 It a process in which solvent is removed from a frozen drug solution or suspension containing structure
forming excipients.
 Tablets formulated by this technique are usually very light and porous in nature which allows their rapid
dissolution.
 The glassy amorphous porous structure of excipients, as well as the drug substance produced with freeze
drying, results in enhanced dissolution.
 Freeze drying process normally consists of three steps:
• Material is frozen to bring it below the eutectic point.
• Primary drying to reduce the moisture around 4% w/w of dry product
• Secondary drying to reduce the bound moisture up to required final volume.
Example: -Loratidine (claritin reditapp )

4. TABLET MOLDING

5. TABLET MOLDING
 Molding process is of two type’s i.e. solvent method and heat method.
 Solvent method involves moistening the powder blend with a hydro alcoholic solvent
followed by compression at low pressures in molded plates to form a wetted mass
(compression molding).
• The solvent is then removed by air-drying.
• The tablets manufactured in this manner are less compact than compressed tablets and
possess a porous structure that hastens dissolution.
 Heat molding process involves preparation of a suspension that contains a drug, agar and
sugar (e.g. mannitol or lactose) and pouring the suspension in the blister packaging wells,
solidifying the agar at the room temperature to form a jelly and drying at 30oC under vacuum.
 Advantages:
• Moulded tablets disintegrate more rapidly and offer improved taste because the dispersion

6. SPRAY DRYING

7. SPRAY DRYING
 The main aim of spray drying is to obtain dry particles with desired properties.
 Orally disintegrating tablets are made up of hydrolyzed or unhydrolyzed gelatin as supporting agent for
the matrix, mannitol as a bulk agent, and sodium starch glycolate and croscarmellose sodium as a
disintegrating agent.
 Citric acid and sodium bicarbonate are also used in order to improve disintegration and dissolution.
 Finally, the formulation is spray-dried in a spray drier. ODTs prepared through this method are
disintegrated in <20 seconds.
 Advantages:
• Formulated tablets were evaluated for hardness, friability, in vitro disintegration time and in vitro drug
release.
• Granules obtained by spray drying technique were found to be more spherical which improved its flow
property and was supported by scanning electron microscope studies.

8. Fig: Flow chart for coating liquid and solid particles using
spray-drying process

9. SUBLIMATION

10. SUBLIMATION
 Tablets manufactured by this technique are stated to usually disintegrate in 10-20 seconds.
 Inert solid ingredients that volatilize readily such as urea, ammonium carbonate, ammonium
bicarbonate, hexamethylenetetramine, camphor were added to the other tablet ingredients, and the
mixture is compressed into tablets.
 Mannitol and camphor were used, respectively, as tablets matrix and subliming material.
 Camphor was vaporized by subliming in vacuum at 80°C for 30 minutes to develop pores in the
tablets.
 The volatile materials were then removed via sublimation, which generates porous structures.
 Advantage: Sublimation of camphor from tablets resulted in superior tablets as compared with the
tablets prepared from granules that were exposed to vacuum

11. Fig: Schematic diagram of sublimation techniques for preparing fast
dissolving tablets

12. MELT GRANULATION

13. MELT GRANULATION
 Melt granulation technique is a process by which pharmaceutical powders are
efficiently agglomerated by a meltable binder.
 The advantage of this technique compared to conventional granulation is that
no water or organic solvents are needed.
 For accomplishing this process, high shear mixers are utilized, where the
product temperature is raised above the melting point of the binder by a
heating jacket or by the heat of friction generated by impeller blades.

14. PHASE TRANSITION

15. PHASE TRANSITION
This method is to prepare ODTs with sufficient hardness by involving the phase
transition of sugar alcohol.
In this method, ODTs are produced by compressing and subsequently heating
tablets that contain two sugar alcohols, one with high and other with a low
melting point.
 The heating process enhances the bonding among particles leading to
sufficient hardness of tablets which was otherwise lacking owing to low/little
compatibility.

16. DIRECT COMPRESSION

17. DIRECT COMPRESSION
 The disintegrant addition technology (direct compression) is the most preferred technique to
manufacture the tablets due to certain advantages:
• High doses can be accommodated and final weight of the tablet can exceed that of other methods.
• The easiest way to manufacture the tablets.
• Conventional equipment and commonly available excipients are used.
• A limited no. of processing steps are involved.
 Tablet size and hardness strongly affect the disintegrant efficacy. Hard and large tablets have more
disintegration time than normally required. Very soft and small tablets have low mechanical strength.
 So, an optimum kind and concentration of disintegrant should be chosen to achieve quick
disintegration and high dissolution rates.

18. SUGAR BASED
EXCIPIENTS

19. SUGAR BASED EXCIPIENTS
 The use of sugar-based excipients is especially bulking agents like dextrose, fructose,
isomalt, lactitol, maltitol, maltose, mannitol, sorbitol, starch hydrolysate, polydextrose, and
xylitol, which display high aqueous solubility and sweetness, and hence impart taste
masking property and a pleasing mouth feel.
 It have been classified into two types on the basis of molding and dissolution rate.
• Type 1: Saccharides (lactose and mannitol) exhibit low mouldability but high dissolution
rate.
• Type 2: Saccharides (maltose and maltilol) exhibit high mouldability and low dissolution
rate.

20. REFERENCES
Gupta AK, Mittal A, Jha KK. Fast dissolving tablet-A review. The pharma innovation. 2012 Mar 1;1(1).
Kumar NP, Nayyar P, Kumar SP. Fast dissolving tablets - A review. Middle East J Sci Res 2015;23(1):142-8.
Deepak H, Geeta A, Hari Kumar SL. Recent trends of fast dissolving drug delivery system - An overview of
formulation technology. Pharmacophore 2013;4(1):1-9.