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43 terms

Pharmaceutics - Capsules

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Capsules
Solid dosage forms in which medicinal agents are enclosed in a small shell of gelatin (hard or soft)
Contain gelatin, water, colorants, & optional materials like process aids or preservatives
Advantages of capsules
Odorless
Tasteless
Easily swallowed (consider caplets)
Elegant
Soft gelatin capsules
contain plasticizers like glycerin or sorbitol
Composition of Hard Gelatin caps
Gelatin
Water
Additives (Dyes, opaquing agent, preservative)
Hard Gelatin Cap formulation
Active ingredient
Filler/diluent (direct compression fillers preferably for flow and compactibility)
Lubricants
Glidants
Disintegrants
Gelatin
Natural - hydrolysis of collagen
Major component of caps
Nontoxic and acceptable to use worldwide
Readily soluble at body temp
Good film-forming material - strong & flexible films
Solutions of high concentration mobile at 50 C
Solution in water or in water-plasticizer blend undergoes reversible change from sol to gel at temps only a few degrees above ambient
Type A gelatin
produced by acid hydrolysis
- takes about 7-10 days, used maily for procin skins - require less pretreatment than bones
Type B gelatin
produced by basic hydrolysis
10 x as long, use for bovine bones
Limitations for properties of materials used for filling caps
Cannot react with gelatin
Cannot contain high level of free moisture
Volume of the unit dose cannot exceed the sizes of capsules available
Colorants
Water soluble dyes and insoluble pigments
Pigments and dyes mixed for range of colors
Dyes mostly synthetic, subdivided into azo and non-azo dyes
Pigments not absorbed on ingestion
Process Aids
Sodium lauryl sulfate - wetting agent
Usually no need for preservatives - water activity will not support bacterial growth (bonded to gelatin)
Hard Gelatin Capsule Shell
Mostly from gelatin, some from HPMC (hypromellose)
religious, cultural or other reasons - alternatives to animal derived components
HPMC slower speed of gelling - machine output reduced
Gelatin caps unsuitable for aq liquids because water softens gelatin, distorts cap resulting in leakage
Dipping process
metal molds dipped into hot gelatin solution, which gels to form a film
Higher the viscosity, the thicker the shell wall produced
Dried, cut to length, removed from mold & 2 parts are joined together
Fill Options
Solid at ambient temp, liquefied by heating (thermosoftening mixture)
Liquefied by stirring - thixotropic mixture
liquid filling - how to protect/guard against leakage, gelatin seal
Granules or coated pellets or tabs
Formulation Modifications
Protect stomach - enteric film coating around filled caps or formulate contents as pellets & coating with enteric polymer
Enteric coated
soluble at only high pH further down GIT for targeting specific sites or coatings that are disrupted by colon specific enzymes
Floating capsules
Contain various hydrophillic polymers that swell on contact with water and form a mass that can float on gastric fluids - dissolve slowly, releasing continuous flow of solution into intestine
Characteristics of formulations to be filled into caps
Capable of being filled uniformly to give stable product
Release active contents in form available for absorption
Comply with requirements of pharmacopeial and regulatory authorities
Release of active ingredient starts by disintegration of capsule shell
Dissolution from Hard Gelatin Cap
Dissolution rate of shell
Rate of penetration of dissolution medium
Rate of deaggregation of powder mass
Nature of primary drug particles
Cross-linking can reduce shell solubility in water
Hard Gelatin Caps advantages
Flexibility of formulation (easy compounding, strong compact not required, unique mix fills, easy for clinical trial material)
Can achieve IR and MR profiles
Once sealed, good barriers to O2
Hard Gelatin Caps Disadvantages
Encapsulation machines slower than tablet machine
Bulky material difficult to fill
Concern maintaining proper shell moisture content (too dry - brittle, fractured, too moist - too soft, sticky)
Cross-linking issues for all cap products
Encapsulation
Manual or automatic filler
Different DFs
Capsule dosage forms
Powders, pellets, microtablets, tablet, tablet/powder or pellet/tablet combinations into 2 piece gelatin capsule
Manual capsule filling machine
Loads caps in machine, removes top halves, fills remaining halves with powder, tamps, and closes capsules all in one simple procedure
Continuous motion capsule filling machines
Designed for speed, reliability, economy, and precision
Caps filled with powder or pellets using a single tower design that performs simultaneous operations.
Dosing precise to within 1%
Softgels
Similar to hard gelatin caps except plasticizer incorporated in shell
Made of modified starch
Usually filled with liquids or suspensions
Filling with dry solids and compressed tabs possible
Softgel Advantages
May result in improvement of rate and extent of drug absorption
High accuracy in filling
Good sealing
Faster onset of action
Less dustiness
Ease of swallowing, convenience, absence of poor taste
Softgel disadvantages
High specialization required for manufacturing
More costly than tabs or hard caps
Can fill only one kind of fill
Softgels
Colored, flavored, transparent,opaque
enteric or DR
PO
Chewable, suckable, twist-off, meltable
Components of Softgel
1. gel mass that will provide softgel shell
2. fill matrix of softgel contents
- drug may be present in both shell and the fill matrix, but commonly in matrix
Softgel shell
Gelatin in water at 80C under vacuum, add plasticizer
Once gelatin dissolved, add other components
HOt gell mass transferred through pipes to encapsulation machine, forming 2 separate gelatin ribbons
During casting, gelatin passes from sol to gel - carried through rollers
Liquid Fill Matrix
Drug (dissolved or dispersed in non-aq vehicle)
Selection of Liquid Fill matrix
Capacity to dissolve drug
Capacity to retain drug in solution in GI
Rate of dispersion in GIT after softgel shell rupture and release of fill matrix
Compatibility with softgel shell
Ability to optimize rate, extent and consistency of drug absorbed
Types of softgel fill matrices
lipophilic liquids
hydrophilic
self emulsifying oils
micro and nanoemulsions
Perconcentrate
softgel fill matrix is combo of lipophilic and hydrophilic liquids with surfactant components - p po admin --> disperse to form microemulsion or nanoemulsion
Manufacture of softgels
Accurately measured volumes of fill matrix injected into space between gelatin ribbons
Forces gel to expand into pockets of dies - govern size & shape
Capsule halves are sealed together with application of heat & pressure
Manufacture - careful control of
Temp - heat for cap seal formation
Timing - timing of dosing of unit quantities during formation
Pressure - pressure exerted between 2 rotary dies controls softgel shape and final cut out from gel ribbon
Softgel Formulation
Gelatin
Plasticizer
Water
Materials for appearance (colorants, opacifiers)
Flavors
Gelatin (50% of wet molten gel mass)
- most commonly type B gelatin
Plasticizers
Make softgel shell elastic and pliable
20-30% of wet gel formulation
glycerol
Amount and choice of plasticizer contribute to product hardness, may affect dissolution or disintegration
Selected on basis of compatibility with fill formulation, ease of processing, desired properties of final product
Water
ensures proper processing during gel prep & softgel encapsulation - removed by drying
Greatest advantages - softgels
To convert a liquid formulation into a solid dosage form, encapsulate into soft gelatin capsule
Product testing - in process
gel ribbon thickness
softgel seal thickness at time of encapsulation
Fill matrix weight
Capsule shell weight
Softgel shell moisture level
Softgel hardness at end of drying
Product testing - finished product
Capsule appearance
Weight variation
Disintegration
Dissolution
Moisture permeation test
Active ingredient assay
Fill weight
Content uniformity
Microbiological testing