Commercial Manufacturing Pharmaceutical Unit Processes Flashcards
(24 cards)
Mixing is putting together of ingredients in _____ with more or less thorough dispersion of the constituted elements among one another
Objective:
One mass or assemblage
To obtain dosage units of the SAME QUANTITY of drug substance
Fluids mixing mechanisms
Involves the movement of a relatively LARGE PORTION of the fluid being mixed from one location to another
Makes use of _____
_____ which move adjacent volumes of the fluid in _____
Must result in a _____ of the various portions of the fluid being mixed to be considered effective
Bulk transport
Paddles, Revolving blades
Shuffling- 3D directions
Rearrangement or permutation
Fluids mixing mechanisms
It is the direct result of TURBULENT fluid flow which is the _____ of fluid velocity at any given point within the system
Meaning of TURBULENT
Turbulent mixing
Random fluctuations
Moving in an irregular or violent way
Fluids mixing mechanisms
Based on STREAMLINE or LAMINAR flow
Encountered in processing _____, but also stirring that is gentle adjacent to stationary surfaces in a vessel
Achieved by mixers which _____ the fluid being mixed
Laminar mixing
Highly viscous liquids
Stretches and folds
Fluids mixing mechanisms
Involves DIFFUSION which results from _____ of the molecules
Usually performed with LAMINAR mixing to _____ at the interfaces between the fluid layers
Molecular diffusion
Thermal motion
Reduce sharp discontinuities
Equipment
Used when material to be mixed is LIMITED IN VOLUME and can be conveniently contained in a suitable mixture
System consist of two primary component
Batch mixing
Tank or container to hold while mixing
A means of supplying energy for rapid mixing
An equipment of batch mixing
It produce RADIAL flow
It produce AXIAL and TANGENTIAL flow
Most EFFICIENT when they can run at high speed in liquids of relatively low viscosity
Impellers
Propeller
Turbines
Propellers
An equipment of batch mixing
Usually arranged in a way that allows the BUOYANCY of the bubbles to lift the liquid from the bottom to the top of the mixing vessel
Used in liquids of
Air jets
Low viscosity, non-foaming, unreactive with the gas employed and non-volatile
An equipment of batch mixing
Fluids are pumped through NOZZLES arranged to permit GOOD CIRCULATION of material throughout the tank
Generates _____ in the direction of their axes, does not generate _____
Fluids jets
Turbulent flow, tangential flow
Pump fluid itself
This produces an UNINTERRUPTED supply of freshly mixed materials
Desirable in handling _____ of material
The feed rate within the tube is carefully controlled and should be uniform via an _____
If the rate is difficult to control what is used
Complex arrays of interconnected tanks can be used for _____
Continuous mixing
Very large volumes
Exact metering device
Tank
Mixing
Continuous mixing is accomplished through the use of
Tube or pipe
Chamber
Factors to consider in mixer selection
Physical properties of materials (density, viscosity, miscibility)
Economic considerations (time required, powder expenditure)
Cost of equipment and maintenance
Selection of equipment depends on VISCOSITY and DENSITY of the fluid
A. Best mixed by method that generates a HIGH DEGREE OF TURBULENCE and circulate the entire mass of material
B. Mixed by turbines of FLAT BLADE design
Monophase systems
A. Low viscosity
B. High viscosity
Composed of several liquid or solid phases
Involves the SUBDIVISION or DEAGGREGATION of one or more of the passes present with subsequent dispersal throughout the mass of material to be mixed
Polyphase systems
Polyphase systems
Mixing requires the subdivision of one of the phases into GLOBULES which are successively reduced in size and are then distributed throughout the bulk of the liquid
Selection of equipment depends on _____
A. _____: requires HIGH SHEAR rates produces by passing the fluid under HIGH PRESSURE through small orifices
B. _____: dispersed by the shearing action of two surface in CLOSE PROXIMITY and moving at DIFFERENT VELOCITIES
- Achieved in _____
Immiscible liquids
Viscosity
A. Low (emulsions)
B. High (Ointments)
-paddle mixers
HIGH viscosity immiscible liquids are relatively efficient since they
Generate SUFFICIENT shear to reduce globule size
Induce SUFFICIENT circulation of material to ensure UNIFORM dispersion throughout the completed mixture
Polyphase systems
Mixing depends on SEPARATION OF AGGREGATES into primary particles and the distribution of these particles throughout the fluid
Mixing is done with the help of _____ which generate shear forces of sufficient intensity to _____
Finely-divided solids in liquids
High speed turbines, disrupt aggregates
Finely-divided solids in liquids
A. _____: efficient in DEAGGREGATION of solids but are typically inefficient in distributing the articles uniformly throughout the entire mass
B. _____: composed of ABRASION-RESISTANT ROLLERS
A. Muller mixers
B. Roller mixers
Batch mixing
_____: consists of a container of one of several GEOMETRIC forms
The resulting motion is accentuated by means of _____ or simply by virus of the shape of the container
Tumbling mixers
Baffles: restrain the flow of prevent spreading sound or light
Efficiency of tumbling mixers depend on the _____
A. _____: not produce the desired intense tumbling or cascade
B. _____: tend to produce CENTRIFUGAL FORCES sufficient to hold the powder to the sides
Optimum rate of rotation ______
Speed of rotation
A. Too slow
B. Too rapid
30-100 rpm
Batch mixing tumbling mixers
Takes the form of a cylinder that has been cut in half approximately a 45 degree angle with it’s long axis and then rejoined to form a V SHAPE
The material _____ which causes the final blend to be very HOMOGENOUS
Twin-shell blender or V blender
Batch mixing
Consists of a container to hold the material and moving crews, paddles or blades to bring about mixing
Does not depend entirely on _____; useful in mixing solids that have been _____
A. _____: consists of a HORIZONTAL cylindric tank.
B. _____: powders are lifted by a centrally located VERTICAL screw and allowed to cascade to the bottom of the tank
Stationary mixers
Gravity, wetted (sticky or plastic state)
A. Ribbon blender
B. Helical flight mixer
Large mixers have _____ in composition than small mixers
Greater variation
Metered quantities of the powders or granules are passed through a device that reduces both the SCALE and INTENSITY of segregation, usually by impact or a shearing action
May be transferred directly to capsule filling or tablet machines
Continuous mixing
