General consideration for Process design of lyophilized product

By.Rajeev Sharma

Lyophilization is commonly used in the pharmaceutical and biotech industries to improve stability and shelf life of parenteral dosage forms.

The scope of molecules that are typically lyophilized include proteins, peptides, liposomes etc. .

Lyophilization

Solution Lyophilized Cake

Lyophilization Lyophilization

•Definition- A dehydration process typically used to preserve a perishable material or make the material more convenient for transport.

A process where water is removed from a product after it is frozen and placed under vacuum Ice “sublimates” from solid to vapor without forming a liquid“Three” steps

Freezing (Ramping Time , Annealing or Not, Freezing Temp)

Primary drying (Collapse T, Eutectic T, Glass Transition T,

Pressure Rise , Dew Point & Vacuum Degree )

Secondary drying (Temp. of Drug degradation , Pressure rise )

Lyophilization

Lyophilization

Form Of Water

Desired Freeze Dried Characteristics Sterile & Free from Pyrogen Uniform appearanceIntact cake (Remains intact after shipping/handling)Low moisture contentMinimal particulatesReasonable reconstitution timeChemically Stable

RobustReproducibleScale of manufacture, clinical? commercial?QbDAnalytical testingSpecification settingStability studies

Desired Process design for Lyophilization

Challenges to the pharmaceutical scientist in developing a lyophilized dosage form include:

Excipient selection

Container/closure system

Biocompatibility

Pre formulation and formulation development studies

Reconstitution must result in a biocompatible solution suitable for IV infusion, IM injection or SC injection

Critical Points for Consideration

Critical Points For Consideration

Critical Points for Consideration

Excipients

Bulking Agent- Build structure upon sublimationSucroseMannitolMaltoseDextrose Lactose

ExcipientsStabilizers

• Cryoprotectants (during freezing) they dissolve in water and lower the melting point of water / A cryoprotectant is a substance used to protect biological tissue from freezing damage (i.e. that due to ice formation)

Eg. - PEG, ethylene glycol, propylene glycol, and dimethylsulfoxide (DMSO)

• Lyoprotectants (during drying) Lyoprotection was defined as the stabilization and prevention of the degradation of a macromolecule both during freeze-drying and afterwards, during storage.)

Eg. – Disaccharides (Sucrose, Maltose , Lactose)

Excipients

Buffers• Citrate• Histidine

Avoid salts that undergo pH change during freezing such as

• Phosphates

Excipients

Tonicity Adjusters•NaCl•Mannitol•Sucrose(caution using in some patient populations)•Glycine•Glycerol

Container Closure Selection

Vial size•2 mL, 5 mL, 10 mL, 20 mL, >20 mL

Vial type•Glass•Other

Stopper•Material•Coating•Size - 13 mm, 20 mm

•Crimp seal•Color•Type

Vials, Rubber stopper & Seals Vials , Rubber stopper & Seals

Glass Transition Tg and Collapse Tc Temperatures

In the great majority of cases the solutes do not crystallize at the solubility limit, ice continues to form as the temperature is decreased and the solution continues to concentrate until it is so viscous it turns to glass.

This it does at a characteristic and reproducible temperature, the glass transition temperature Tg'. The “prime” mark is used to denote this is the glass formed by freeze concentration, a glass which may still contain 20-50% by weight of unfrozen water.

Glass Transition Tg and Collapse Tc Temperatures

This water is not bound in any way but diffusion is limited by the extremely high viscosity of the glass. For products that behave like this, Tg' is the temperature at which the ice starts to melt back and the product starts to collapse. (i.e. Tc=Tg′).

The glass transition and the eutectic melt have quite different profiles in a DSC scan, the glass transition is a step like transition whereas a eutectic melt appears as a peak, or trough depending upon the set up of the DSC.

Collapse Temperature

Crystalline state-If decreasing the temp crystal appears (liquid to solid) is known as eutectic temp. and latent heat was released in this process.Glassy state- if decreasing the temp. where liquid changes in glass (not solid) that temp is know as glass transition temp.

Collapse Temperature

In Drying process ice sublimates through the pores as shown in picture (left side) but if we increase the temp continuously brown layer of drug change (shown at right side) the pores start blocking up above the layer of ice , where water does not removed at the point, this temp is known as collapse temp.The value of collapse temp. depends on the drugs properties, formulation , cooling methods and so on.

Collapse temp. can be determined by Freeze drying microscope (FDM). Light black is frozen layer , black portion is drying layer and border line between both is sublimation front.If we increases temperature continuously the drying layer starts increasing and sublimation front starts increasing from left to right. at the particular temperature The water blockage starts which is shown in right pic (white border) which is collapse region. We can not make the product collapse. The collapse temperature is the safest temp of primary drying.

Components Tg Tc

Protein

Glycosidase -29 -15Ovalvumin -11 -10

ruhMAB HER - -20

Sugar

Sucrose -32 -31Trehslose -29 -28.5Lactose -28 -30.5Maltose -30 -

PolyolsGlycerol -65 -Sorbitol -46 -Mannitol -35 -1.4

Polymers

Dextran (70K) -10 -10Polyvinylpyrrolidone

(PVP) (40 KD) -21 -24Ficoll -19 -20

Gelatin -9 -8

Hydroxyethyl Starch -12 >-5

Amino AcidGlycine -62 -3.5Alarrine -65 -Histidine -33 -

Salts

Sodium acetate -64 -Sodium citrate -41 -

KH2PO4 55 -K2HPO4 65 -

NaCl -60 -CaCl2 -95 -ZnCl2 -88 -

Preformulation Studies

SolubilitypH stabilityStability under different temp. DSC thermo gramsGlass transition temperatureCounterionBuffer saltPolymorphism

Formulation Process Studies

Aseptic process designSterile filter selection

•Compatibility•Formulation•Microbial retention•Filter validation

Compatibility with compounding vessels, tubing, etc.Bulk solution stabilityBioburdenFill volume

Process Design Studies

Pre-freeze•Shelf temp

Freeze•Pore structure determined by freezing rate•Desired crystalline structure•Maintain well below Tg

AnnealPrimary Drying

•Sublimation under vacuum•Avoid melt back while achieving reasonable cycle time

Secondary Drying•Isothermal desorption of bound water

Post Cycle•Stopering

Process Flow

Process Flow

Stability Testing

AppearanceReconstitution timePotencyPurityWater contentpHSterilityEndotoxin

Setting of Specification

In-process•Potency•pH•Osmolality•Density•Bioburden•Appearance

Fill weight

Setting of Specification

Finished product•Potency•Purity•Reconstitution time•Appearance•Sterility•Endotoxin

Thanks