Hard gelatin capsule structure
Two pieces, cap and body
Soft gelatin capsule structure
One piece
Advantages of capsules
Avoid many steps of tablet manufacture, may improve bioavailability of poorly water soluble drugs, convenient way to administer some liquids, difficult to counterfeit, stability of drug may be improved, diversity of filling, ideal for clinical trials and drug studies
Disadvantages of capsules
Require specialised equipment, potential stability problems if containing liquid fills, problems related to homogeneity of fill weight and content, slower than tablet manufacture
Benefits of gelatin
Non toxic, worldwide acceptance, readily soluble in biological fluids, good film forming material, changes from solid to gel a few degrees above ambient temperature
Water soluble colourants
Azo or non-azo dyes
Insoluble pigments
Iron oxide, titanium dioxidesW
What colourants are more commonly used in capsules and why
Insoluble pigments as they are not absorbed
What is the largest capsule size
000
What is the smallest capsule size
5
Ways of sealing hard gelatin capsule
Gelatin band sealing, hydro-alcoholic solvent seal
How does gelatin band sealing work
Dilute solution of gelatin applied to centre of capsules, when dry produces seal
How does hydro-alcoholic solvent seal work
Solution of equal parts ethanol and water applied to centre of capsule, soften capsule, heat to 45 degrees, interface fuses to produce seal
Steps in filling hard gelatin capsules
Rectification, separation, filling, joining, ejection
Methods for powder filling on an industrial scale
Dependent method, independent dosing systems
Dependent method of capsule fillin
Lower half capsule in revolving turntable, rotated under hopper containing powder, flow and homogeneity maintained by circular movement, at end of operation two halves bought together
Independent dosing systems
Tube containing spring loaded piston depressed in powder bed, enables plug to enter tube, tube with plug elevated out of powder bed, rotated, put over lower half of capsule, powder plug dispensed
What are softgels
Capsules whose mechanical properties have been manipulated by adding plasticisers, more flexible
Components of softgels
Gelatin (normally type B), plasticising agents, water, opacifiers (titanium dioxide), colorants, may contain flavor
Fills in softgels
Primarily liquid, sometimes powder, lipophilic liquids, self emulsifying systems, microemulsions, water miscible liquids
Advantages of softgels
Improved drug absorption, easy to swallow, no taste issues, avoid dust handling problems for cytotoxic drugs, overcomes problems with manufacture of compressed tablets, liquid flow more precise which increases dose uniformity, drugs protected against oxidation- more stable
Manufacture of softgels
Two sheets of gelatin ribbon between pair of matched dies, ribbon pressed into dies and medication placed, pressure between two plates enables individual capsules to be cut
What 2 subprocesses are required prior to softgel encapsulation process
Gel mass and liquid matrix