Drying technology used in Pharmaceutical Industry

Different drying technology used in Pharmaceutical Industries

1. PRESENTED BY- MR. DEBASHIS PUROHIT M.PHARM,2ND SEMESTER (INDUSTRIALPHARMACY) DATE-08/02/2018 SCHOOL OF PHARMACEUTICALSCIENCES, SIKSHA ‘O’ ANUSANDHAN (DEEMED TO BE UNIVERSITY), BHUBANESWAR SUBJECT -PHARMACEUTICAL PRODUCTION TECHNOLOGY TOPIC -DRYING TECHNOLOGY USED IN PHARMACEUTICAL INDUSTRY M.PHARM,2 nd SEMeSTER SEMINAR

2. PRINCIPLES OF DRYING [1] Large surface area for heat transfer. Efficient heat transfer per unit area (to supply sufficient latent heat of vaporization or heat of sublimation in case of freeze-drying) Efficient mass transfer of evaporated water through any surrounding vapour boundary layers, i.e. sufficient turbulence to minimize vapour boundary layer thickness . Efficient vapour removal , i.e. low relative humidity air at adequate velocity.

3. Different Machinaries used in Pharmaceutical drying [2] Fluidized bed drying Drum dryer Rotary Dryers Lyophillization (Freeze drying)

4. FLUID-BED DRYERS PRINCIPLE The particulate matter is contained in a vessel, of which is perforated, enabling a fluid to pass through the bed of solids from below. If the air velocity through the bed is increased gradually and the pressure drop through the bed is measured, a graph of the operation shows several distinct region s.

5. WORKING Material to be dried is placed on the bowl and heated and air is passed for heating . Then air is passed through the filter and passed through bed of material. The air flow is generated by fans fitted at the top . As the flow increases the bed bag expands and particles of powder start a turbulent motion. Due to the regular contact with a material gets dry. The air leaving the FBD passes through the filter to collect the fine particles of the material.

6. Advantages Efficient heat and mass transfer give high drying rates, so that drying times are shorter than with static-bed convection driers . Economic , heat challenge to thermoliabile materials is minimized. The fluidized state of the bed ensures that drying occurs from the surface of all the individual particles and not just from the surface of the bed. Hence, most of the drying will be at constant rate and the falling rate period is very short. The temperature of a fluidized bed is uniform and can be controlled precisely.

7. DISADVANTAGES The turbulence of the fluidized state may cause excessive attrition of some materials, with damage to some granules and the production of too much dust . The vigorous movement of particles in hot dry air can lead to the generation of static electricity charges. The danger is increased if the fluidized material contains a volatile solvent such as isopropanol . Adequate electrical earthing is essential .

8. USES It is used to reduce or minimize the liquid moisture content of the material.

9. DRUM DRYERS PRINCIPLE- In drum dryers, slurries or pasty feedstock's are dried on the surface of a slowly rotating steam- heated drum. A thin film of the paste is applied on the surface in various ways. The dried film is not monitered once it is dry and collected as flakes (rather than powder).

10. WORKING At first liquid is kept in a feeding pan in which the heated drum is applied to the surface and spreads to a film which dries rapidly. The dried product is scrapped from the surface of the drum by means of “Doctors knife” in the form of flakes. The drying rate can be controlled by adjusting rotation speed and temperature of drum.

11. A DVANTAGES It is quick method and c ompact . It’s heating time is short. Drying temperature can be reduced by enclosing in a vacuum chamber.

12. DISADVANTAGES Operating conditions are critical and it is necessary to introduce careful control on : Feed rate. Temperature of drum. Thickness of film. Speed of rotation of drum.

13. USES Milk products. Starch powder. Iron salts. Suspensions of kaolin or zinc oxide.

14. ROTARY DRYERS PRINCIPLE- Rotary Dryer is a simple, inexpensive unit for reducing the moisture content of flotation concentrates, as well as chemical and industrial products. Frequently the saving of shipping weight so effected will pay for the dryer in a few months. Difficulties from freezing while in transit are also eliminated. Many industrial projects are now using Dryers for control and production purposes on many materials.

15. WORKING The dryer is made up of a large, rotating cylindrical tube, usually supported by  concrete columns or  steel beams. The dryer slopes slightly so that the discharge end is lower than the material feed end in order to convey the material through the dryer under  gravity. Material to be dried enters the dryer, and as the dryer rotates, the material is lifted up by a series of internal fins lining the inner wall of the dryer. When the material gets high enough to roll back off the fins, it falls back down to the bottom of the dryer, passing through the hot gas stream as it falls.  

16. ADVANTAGES Rotary dryers are less sensitive to particle size. It can accept the highest flue gasses of any type of dryer. Low maintenance cost;thus economical. It has the greatest capacity than any type of dryer.

17. DISADVANTAGES Excessive entrainment losses in the exist gas stream is possible especially if the material contains extremely fine particles due to the large gas volumes and high gas velocities that are usually required.

18. USES These are mostly used in the mineral industry for drying sands,limestone,fertilizers,coal,iron sulphate etc.

19. Lyophilization PRINCIPLE- Lyophilization , or cryodesiccation —is a dehydration process typically used to preserve a perishable material or make the material more convenient for transport.

20. WORKING Sublimation in the freeze drying process can be described simply as: FREEZE - The product is completely frozen, usually in a vial, flask or tray. VACUUM - The product is then placed under a deep vacuum, well below the triple point of water. DRY – Heat energy is then added to the product causing the ice to sublime.

21. ADVANTAGES Removal of water at low temperature. Thermoliable materials can be dried. Compactable with asceptic operations. Sterility can be maintained.

22. DISADVANTAGES Many biological molecules are damaged by the stress associated with freeze-drying or both. Cost may be an issue depending upon product. It is a long time process.

23. USES It is used in pharmaceuticals and biotechnology to increase the shelf life of the product. It is used in food industry to preserve food,produce essence or flavouring agents. In technical industry it is used in chemical synthesis and formation of stable product.

24. REVIEW ARTICLE-1 Crystallization processes in pharmaceutical technology and drug delivery design Shek nov et al; suggested that crystallization possess a major role for particle formation in pharmaceutical Industry as well as it plays a vital role in defining stability and drug release properties of final dosage form by the process of direct compression and formation of amorphous,solvated and polymeric form and finally recent development in supercritical technology was considered for crystallization process.

25. REVIEW ARTICLE-2 Freeze drying Process: A Review Soham sukla has suggested ‘Freeze drying’ method for drying thermoliable materials which involed 3 steps. 1-freezing-Here freezing material was kept in a freeze drying flask and rotating the flask in a bath called shell freezer, which was cooled by mechanical refrigiration . 2-Primary drying-In this phase pressure was lowered and enough heat was supplied to the material and about 95% of water was sublimated. 3-Secondary drying-Here temperature is raised higher then in primary raised above 0 degree celcius to break any physico chemical interactions that have been happened between water molecules and frozen materials. After the freezedrying process is complete vaccum is usually broken with an inert gas and at the end the residual water content in the product was 1 to 4% which is extremely low.

26. REFERENCE RM Mehta, Pharmaceutics-I: introduction to the drying process, Page no-194(1996). C.V.S. Subrahmanyam ,J. Thimma Setty,Sarasija Suresh, V. K usum D evi pharmaceutical engineering principles and practices-filtration, page no. 394 – 397(2001). Crystallization processes in Pharmaceutical technology and drug delivery design. B.Yu Shekunov,P York. Asian Journal of Pharmaceutical Sciences,10(4),Page no-283-291, ( 2015) Freeze Drying Process:A Review.Soham Shukla . International Journal of Pharmaceutical Sciences,11(2),(2011).