An Insight into Orally Disintegrating Tablets

Orally disintegrating tablets (ODTs) have become one of the preferred dosage forms. Their growing popularity stems from the benefits they offer which conventional tablets fail to provide. Swallowing conventional tablets is a significant problem for the paediatric, elderly, bedridden patient, psychiatric patients, patients on a low fluid diet, and disabled patients. Also, the conventional tablets need to be taken with water which may not be possible or convenient in certain cases. This results in poor or even noncompliance in patients leading to failure of the overall treatment. 

ODTs overcome several of the challenges presented by conventional tablets:  

  • When placed in the mouth, ODT rapidly disintegrates or dissolves in the saliva of the buccal cavity forming a slurry or suspension which can be easily swallowed by the patient. 
  • The rapid dissolution of the tablets leads to a rapid onset of action. 
  • Since ODTs are easily swallowed, they can be taken without water.  
  • Drugs that are susceptible to the first-pass metabolism can be administered as ODTs as the drug gets absorbed across highly permeable buccal and mucosal membranes of the oral cavity leading to increased bioavailability.     

For pharma companies, ODTs offer both process and commercial benefits: 

  • Increase in drug loading capacity 
  • Fast scale-up of the manufacturing process 
  • An opportunity of retaining the patent exclusivity and product life cycle management  
  • Brand differentiation in a competitive market 
  • Product line extension

 

Working on formulation  

Formulation of ODTs requires a critical focus on the use of disintegrants and appropriate tastemasking agents for bitter active pharmaceutical agents. The excipients for ODTs should also ensure shorter disintegration time, compliance with the pharmacopoeial specifications, and be compatible and inert with the therapeutic agent.  

Superdisintegrants These are the crucial ingredients in ODTs since the tablet must disintegrate quickly within seconds when put inside the mouth. Superdisintegrants are substances that when added to the tablet formulation, facilitate the breaking of the tablet rapidly once it is placed inside the mouth. Some of the important properties that should be considered when selecting the superdisintegrant are flowability and compressibility, good hydration, poor water-solubility, and inability to form complexes with drugs. Sodium-starch glycolate, crospovidone, and carboxymethylcellulose sodium are few examples of superdisintegrants used frequently in the ODT formulations. These may be combined with natural superdisintegrants such as lepidiumsativum seed mucilage, isapghulahusk mucilage, gellan gum, and chitosan 

Binders Lactose, sucrose, cellulose-ethers like hydroxypropylmethylcellulose (HPMC), hydroxypropylcellulose (HPC), sugar alcohols such as xylitol, maltitol, synthetic polymers such as polyethylene glycol (PEG), polyvinylpyrrolidone (PVP) are commonly used binders to hold the particles together in the formulation. 

Sweeteners Sweeteners are all the more important in ODTs as palatability is the prime requirement for these dosage forms. The unpleasant taste of the drugs can be masked by either polymer coating, using sugarbased diluents such as mannitol or sucrose, by forming complexes with cyclodextrins, salt formation, microencapsulation, granulation, or by using synthetic sweeteners such as saccharin and aspartame.  

Lubricants – These are added to prevent sticking of powder to the machine, improve flow, and reduce friction with the die wall. 

 

Manufacturing techniques  

Compression, freezedrying, and molding methods are three major techniques used for producing ODTs. However, many technologies such as Orasolv, Flash tab, Flash Dose, Zydis, Durasolv, Wow tab technology have been patented for manufacturing of ODTs.  

  • OraSolv technology uses low compression force during tableting and makes use of the effervescent disintegrating agent for masking and reducing disintegration time.  
  • FlashTab is a combination process of dry and wet granulation before compression using superdisintegrants 
  • Zydis is a freezedried solid oral dosage form in which the API is physically trapped in a watersoluble matrix and then freeze-dried.  
  • Wowtab technology involves mixing the drug with low mouldability saccharide and granulating with high mouldability saccharide before compression.  
  • FlashDose technique involves the use of a spinning mechanism to produce a crystalline floss-like structure which is then compressed and moulded into tablets.  
  • DuraSolv technology was created to make direct compressed tablets that are suitable for packaging in bottles using unique ratios of lubricant and diluent.

 

Evaluation factors 

Evaluation parameters of ODT tablets as mentioned in the pharmacopeias include thickness, weight variation, hardness, friability, wetting time, invitro dispersion time, water absorption ratio, in vitro and in vivo disintegration time, drug content, and in vitro dissolution. In comparison to conventional dosage forms, ODTs have lower hardness and disintegration time in seconds.

 

Recent developments   

The world of ODT formulations is expanding rapidly with the development of newer taste masking and quality by design techniques. Fixed-dose combinations, enteric-coated ODTs, extended-release ODTs, mucoadhesive ODTs are the few advanced versions in this area.  

Fixed drug combinations (FDC) ODTs overcome the drawback of conventional ODTs which are large and hence difficult to swallow. Fixed-dose combination ODTs of Salbutamol and Ambroxol Hydrochloride have been developed by the formulation scientists using the direct compression method. Entericcoated ODTs are formulated for the delivery of drugs that are vulnerable to gastric enzymes or act as irritants to stomach mucosa. Diclofenac enteric ODTs have been developed using Eudragit polymer. Neos Therapeutics has developed Amphetamine (Adzenys XR-ODT) and methylphenidate (Cotempla XR-ODT) extendedrelease (ER) ODT that are approved by FDA. Mucoadhesive ODTs make sure that disintegrated particles adhere to the site of action for sustained activity. Oral care ODTs containing tamarind gum coated tea powder have been developed. 

 

References 
  1. Nagar, P., Singh, K., Chauhan, I., Verma, M., Yasir, M., Khan, A., … & Gupta, N. (2011). Orally disintegrating tablets: formulation, preparation techniques and evaluation. Journal of Applied Pharmaceutical Science, 1(04), 35-45. 
  2. Hirani, J. J., Rathod, D. A., & Vadalia, K. R. (2009). Orally disintegrating tablets: a review. Tropical Journal of pharmaceutical research, 8(2). 
  3. Pahwa, R., Piplani, M., Sharma, P. C., Kaushik, D., & Nanda, S. (2010). Orally disintegrating tablets-Friendly to pediatrics and geriatrics. Archives of applied science research, 2(2), 35-48. 
  4. Badgujar, B., & Mundada, A. (2011). The technologies used for developing orally disintegrating tablets: a review. Acta Pharmaceutica, 61(2), 117-139. 
  5. Nayak, A. K., & Manna, K. (2011). Current developments in orally disintegrating tablet technology. Journal of Pharmaceutical Education and Research, 2(1), 21. 
  6. Gauri, S., & Kumar, G. (2012). Fast dissolving drug delivery and its technologies. The pharma innovation, 1(2). 
  7. Sharma, D.; Singh, R.; Singh, G., Orally Disintegrating Tablets in FixedDose Combination containing Ambroxol Hydrochloride and Salbutamol Sulphate prepared by Direct Compression Technique: Formulation Design, Development, and In-Vitro Evaluation. Turkish Journal of Pharmaceutical Sciences, 2018; 15: 29-38.  
  8. Alotaibi, H. F.; Elsamaligy, S.; Mahrous, G. M.; Bayomi, M. A.; Mahmoud, H. A., Design of tastemasked enteric orodispersible tablets of diclofenac sodium by applying fluid bed coating technology. Saudi Pharmaceutical Journal, 2019; 27: 354-362.  
  9. Kiniwaa, R.; Miyakeb, M.; Kimuraa, S.-i.; Itaia, S.; Hiromu Kondoa; Iwaoa, Y., Development of mucoadhesive orally disintegrating tablets containing tamarind gum-coated tea powders for oral care. International Journal of Pharmaceutics 2019; X 100012.  

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