Formulation and manufacturing of suspensions

Industrial pharmacy assignment

1. MAHARSHI DAYANAND UNIVERSITY DEPARTMENT OF PHARMACEUTICAL SCIENCES Assignment of Industrial Pharmacy on : Formulation & manufacturing of suspension Submitted to : DR. DEEPAK KAUSHIK MS. PRERNA KAUSHIK Submitted by : Sagar Khanna B.Pharm , Vth sem. 1432

2. introduction Suspension may be defined as preparation containing finely divided drug particles distributed somewhat uniformly throughout a vehicle in which the drug exhibits a minimum degree of solubility. Suspensions are the biphasic liquid dosage form of medicaments . The range of solid particles in suspension is 0.5 to 5.0 micron . Chemically stable than solution .

3. CLASSIFICATION Based on general classes :- Oral suspension :- eg. Antacids , antibiotics Externally applied suspension :- eg. Calamine lotion Parenteral suspension :- eg. Insulin zinc suspension

4. FORMULATION COMPONENTS WETTING AGENTS : S ubstance which reduce the interfacial tension between the solid particle & liquid phase. It is adsorbed at the solid or liquid interface , in such a way that the affinity of the particles for the surrounding medium is increased & interparticular forces are decreased. The use of wetting agent allows removing the air from the surface and easy penetration of the vehicle into the pores. e.g. alcohol in tragacanth mucilage , glycerin.

5. FLOCCULATING AGENT : Flocculating agent reduces the interfacial tension. Surfactant with negative charge are adsorbed on the particles , minimise flocculation in the presence of positive ions because of natural repulsion of like charge. e.g. of negative charge surfactant : sodium lauryl sulphate, sodium dioctyl sulphocinate etc. Non-ionic surfactant also have negative charge surfactant in solution.

6. DISPERSING AGENTS :- Some particles have not sufficient surface energy, so that particles come together & forms large particle to overcome that difficulty the substances which are introduced in the suspension are called dispersing agent. These substance increase the zeta potential & do not allow the particles to come together to form large particles. They also act as stabiliser in suspension. e.g . glyceryl monostearate.

7. PRESERVATIVES :- It should be effective against wide range of micro organisms. It should be physically & chemically stable . It should be non-toxic & compatible with other added substance . e.g. benzoic acid, sodium benzoate . Fig. – using salt as food preservative

8. SUSPENSION FORMATION Dispersion of Drug Particles : While preparing a suspension of the powders, it is necessary to overcome particle particle attractive force. It s is done by mixing the powders with a minimum required amount of wetting agent either anionic or non-ionic. Concentrated solution of wetting agent is mixed with powders to make slurry , then slurry is passed to a colloid mill so that particles are throughly wetted. While making slurry Glycerine or Alcohol can be used for better penetration.

9. PREPARATION OF STRUCTURED VEHICLE Structured vehicle is an aqueous solution of suspending agent which may be hydrocolloid or polysaccharide or clay. Using high-shear mixer a good dispersion can be prepared,the water in the tank is slowly agitated and powders of suspending agent are sifted slowly over the water in the tank&the individual particle becomes wetted completely. Addition of powders must be completed before the medium becomes thick. Better dispersion is also possible if an eductor is used.

10. A funnel is attached to the top eductor and a high-speed stirrer is fitted to move the water or medium at very speed. When the stirrer is switched on, the water or medium starts moving. Suspending agent are poured into through the funnel. Particles individually are surrounded by water molecules and get properly wetted. No lump can form. Addition of Formulation Excipients : these can be premixed with the suspending agent and mixed with water during prep. of structured vehicle.

11. Incorporation Of Drug Particle : Once the solution of suspending agent is prepared , the dispersion of drug should be gradually added to it with continuous stirring. Deaeration and Volume Make-up : During preparation of structured vehicle and incorporation of drug into it, stirring with high speed is done , air is entrapped into thick preparation. Entrapped air may affect the rheological property as well as stability of the preparation.

12. Homogenization :- After the volume is made-up, the formulation should be finally homogenized to reducethe size of dispersed particles and for their uniform dispersion. There are various equipments available for homogenization of a liquid preparation such as mortar and pestle, dounce homogenizer (manual method), stator-rotor homogenizer, ultrasonic homogenizer, high-pressure homogenizer, etc.

13. Stator-rotor homogenizer A lso called as mechanical shear homogenizer. Most of the rotor-stator homogenizers are of probe-style. These contain smaller motor-driven blades, called knife, at the end of a rotor shaft. When the liquid enters the rotor-stator, the knife creates the shear to disrupt the liquid. Various types of rotor-stator homogenizers with different probe size and power are available to homogenize sample of different toughness and sizes. The probe may be of metal or of plastic , The plastic probe may be disposable, Metal probes are reused after proper cleaning . Latter reduces the human error to some extent .

14. Ultrasonic homogenizer :- Ultrasonic homogenizer uses an electronic generator that sends waves of high frequency mechanical energy to a horn through a transducer. The horn then starts vibrating rapidly. Due to this vibration small bubbles are quickly formed and then collapsed within the system. This process is called as cavitation. Also available at wide range of power & size. Sonicator can effectively break the particles in to very fines up to nano size range . Commonly used for prep. o f nano particles. Main problem is denaturation of proteins .

15. References :- Khar DK , Vyas SP et-al lachman and lieberman , textbook of industrial pharmacy , CBS publisher , 4 th Edition 2013 , page no. 665 – 671 . Tripathi DK , Industrial pharmacy, pharma med press, 2018, page no. 282 – 297. https :// homogenizers.net/collections/rotor-stator-homogenizers https :// webstor.srmist.edu.in/web_assets/srm_mainsite/files/downloads/SUSPENSIONS.pdf