Goals of Preformulation Establish the necessary physicochemical parameters of a new drug substance. Determine drug kinetic rate profile. Develop a stability indicating assay. Establish drug compatibility with common excepients.

Goals of Preformulation Establish the necessary physicochemical parameters of a new drug substance. Determine drug kinetic rate profile. Develop a stability indicating assay. Establish drug compatibility with common excepients.

Types of incompatibility Compatibility tests Types of incompatibility ?

Which Drug/Excepient ratio Compatibility tests Aim ? Which excepient Which Drug/Excepient ratio

? Compatibility tests FDA Guidelines Methods Solid dosage form Liquid dosage form FDA Guidelines

Compatibility test for solid dosage forms Stopper + Wax Drug + Excepient Room Temperature 55oC Without water With water Without water With water Compare to drug stored under same conditions

Compatibility test for solid dosage forms Stopper + Wax Drug + Excepient Room Temperature 55oC Visual examination Analytical assay Quantitative relation of certain excepient character and interaction rate

Compatibility test for liquid dosage forms Aqueous solution Non-aqueous solution Parenteral Oral

Compatibility test for liquid dosage forms Aqueuos solution compatibility Parentral Oral Drug + Excepient solution -Heavy metals Heavy metals+chelating agent Oxygen and nitrogen atmosphere Autoclaving Different blugs -Ethanol Glycerin Sucrose Preservative Buffers

Compatibility test for liquid dosage forms Aqueuos solution compatibility Parentral Oral Drug + Excepient solution Visual examination Analytical assay

Compatibility tests ??? Drug : Excipient ratio The preformulation screening of drug-excipient interaction requires (1 : 1) Drug:excipient ratio, to maximize the likehood of observing an interaction. ??? Some researchers recommend ratios of : 1:5 for diluents 3:1 for binder & disintegrants 5:1 for lubricant 10:1 for colourant

Compatibility tests Analytical Methods Chromatography Vapour Pressure Osmometry Accelerated Storage Testing Thermal Analysis Non-thermal Analysis Radio Labelled Techniques Fluoroscence Measurement Spectroscopy

Compatibility tests Methods Chromatography TLC HPLC

Compatibility tests Methods Chromatography TLC HPLC

Compatibility tests Methods Chromatography TLC HPLC Advantages : Evidence of degradation Spots or peaks isolation. Quantification to obtain Kinetic data. Changes in the chromatograph such as appearance of NEW SPOT or Peak or change in Rf values or Rt means significant interaction.

Compatibility tests Methods Thermal Analysis Isothermal microcalorimetry Differential scanning calorimetry Thermogravimetric analysis Calorimetry is the science of heat. It is about how a given material responds to temperature changes on both the atomic and macroscopic level. It reveals important information about the arrangement and interaction of the atoms.

Differential scanning calorimetry (DSC) Is a thermoanalytical technique in which the difference in the amount of heat required to increase the temperature of a sample and reference is measured as a function of temperature. For solid state

Applications Differential scanning calorimetry (DSC) It detects physical transformation such as melting, dehydration or crystallization Temperature Heat Flow - > exothermic Glass Transition Crystallisation Melting Cross Linking (Cure)

Applications Differential scanning calorimetry (DSC) It detects physical transformation such as melting, dehydration or crystallization Phase equilibrium diagrams of enantiomers Compatibility of drug with excepients

Differential scanning calorimetry (DSC) DSC thermogram for API, Croscarmilose and physical mixture of both

Differential scanning calorimetry (DSC) DSC thermogram for API, Lactose and physical mixture of both

Heat conduction microcalorimetry Isothermal heat conduction microcalorimetry is an analytical method allowing determination of minute amounts of evolved or absorbed heat. The sensitivity is 10 000-fold higher than the sensitivity of conventional differential scanning calorimetry (DSC). By microcalorimetry heat flow signals in the range of µW are detectable. The rate of heat flow is proportional to the rate of the process taking place.

Heat conduction microcalorimetry Fig. 8. Concentration dependent drug-associated heat flow at 258C for a drug concentration of 8.7% NEA and various concentrations of E2-hemihydrate

Heat conduction microcalorimetry For a reaction A + B = C + D First order Zero order

Heat conduction microcalorimetry Time (days) 1 2 -10 10 20 Ø 80oC 75oC Zero-order

For liquid and solid state Heat conduction microcalorimetry Applications Heat conduction microcalorimetry detects chemical changes. BUT it gives no direct information about the chemical nature of the reaction For liquid and solid state

Drug/excepient compatibility Heat conduction microcalorimetry Applications Drug stability Drug/excepient compatibility Liquid state Solid state -Oxidation -Decomposition -Kinetics -Kinetics -crystallization

Thermogravimetric analysis Measures the amount and rate of change in the weight of a material as a function of temperature or time in a controlled atmosphere. Measurements are used primarily to determine the composition of materials and to predict their thermal stability at temperatures up to 1000°C. The technique can characterize materials that exhibit weight loss or gain due to decomposition, oxidation or dehydration.   For solid state

Compatibility tests Methods Non-thermal Analysis X-ray diffraction FT-IR Spectroscopy

FT-IR Spectroscopy Is the absorption measurement of different IR frequencies by a sample positioned in the path of an IR beam. Different functional groups absorb characteristic frequencies of IR radiation. The main goal of IR spectroscopic analysis is to determine the chemical functional groups in the sample.

FT-IR Spectroscopy

FT-IR Spectroscopy Common Applications Identification of compounds by matching spectrum of unknown compound with reference spectrum (fingerprinting) Identification of functional groups in unknown substances. Identification of reaction components and kinetic studies of reactions Detection of molecular impurities or additives present in small amounts . Analysis of formulations such as insecticides and copolymers

Detects chemical interations For liquid and solid state FT-IR Spectroscopy Detects chemical interations For liquid and solid state K. A.Mohammed, H. K. Ibrahim, M. M. Ghorab, Drug Deliv, 2014.

X-ray diffraction X-rays interact with crystalline substances to give a diffraction pattern. The X-ray diffraction pattern of a pure substance is like a fingerprint of the substance. In a mixture of substances, each produces its pattern independently of the others. The powder diffraction method is thus ideally suited for characterization and identification of polycrystalline phases.

X-ray diffraction

Transdermal nonaqueuos solution compatibility -Compatibility with different excepients -Release and permeation characteristics In vitro In vivo With membrane (ex-vivo) Without membrane

Nonaqueuos solution compatibility Time (units) 6 12 18 24 90 100 110 Amount released Flux of oily solution release Flux of solution+membrane release Chein et al., Drug Dev Ind Pharm, 1983.

Transdermal nonaqueuos solution compatibility -Compatibility with different excepients -Release and permeation characteristics In vitro In vivo With membrane (ex-vivo) Without membrane Sacrifice

Emulsion compatibility Preformulation is very formulation oriented: -Surfactant selection -Calculation of surfactant amount -Measuring CMC -Calculating the required HLB -pH stability profile of the surfactant in presence of other emulsion components

Emulsion compatibility Micro/nanoemulsion

Gel compatibility Preformulation is very formulation oriented: -Polymer selection -Drug stability in the gel

Preformulation studies → expected outcomes The product will: Meet specifications (assay, impurities & dissolution rate) Be consistent within & between batches. Is palatable to the patient. Have optimum chemical & physical stability. Fewer formulations fail stability & BA studies Have cost effective manufacture.