HERBAL COSMETIC

HERBAL COSMETIC (PERFORMULATION STUDIES, COMPATIBILITY STUDIES, POSSIBLE INTERACTION BETWEEN DRUGS AND CHEMICALS

1. HERBAL COSMETICS ( Preformulation studies, compatibilty studies, Possible interaction between drugs and chemicals)

2. Preformulation studies

3. INTRODUCTION Preformulation is a group of studies that focus on the physicochemical properties of a new drug candidate that could affect the drug performance and the development of a dosage form. This could provide important information for formulation design or support the need for molecular modification. Every drug has intrinsic chemical and physical properties which has been consider before development of pharmaceutical formulation. This property provides the framework for drugs combination with pharmaceutical ingredients in the fabrication of dosage form. Preformulation study is done to develop the elegant, stable, effective and safe dosage form by establishing kinetic rate profile, compatibility with the other ingredients and establish Physico -chemical parameter of new drug substances. Among these properties, drug solubility, partition coefficient, dissolution rate, polymorphic forms and stability are plays important role in preformulation study. 

4. Preformulation studies include S tudies of Assessment of physicochemical properties of herbal extracts and their relevance to the final formulation The physical and chemical stability of the herbal extracts Compatibility studies of the herbal extracts with potential excipients Objective: The preformulation investigations confirm that there are no significant barriers to the compound’s development as a marketed drug. The formulation scientist uses these informations to develop dosage forms .

5. Principal areas of preformulation

6. Organoleptic characters Color: If the colour is undesirable or variable, incorporation of a dye in the final product is recommended. Taste: If taste is considered to be unpalatable, a less soluble form of the drug (salt or prodrug ) ought to be considered Odor: The substance may exhibit an inherent odor characteristic of major functional groups present. Odor greatly affects the flavor of a preparation or food stuff

7. BULK CHARACTERIZATION

8. Bulk Characterization

9. ANALYTICAL METHOD FOR CHARACTERIZATION OF SOLID FORMS Microscopy Hot stage microscopy Differential Scanning Calorimetry (DSC) Differential Thermal Analysis (DTA) Thermogravimetric Analysis Infrared Spectroscopy X-ray Powder Diffraction Scanning Electron Microscopy Dissolution / Solubility Analysis

10. Microscopy In this type of microscope light passes through cross-polarizing filters. Amorphous substances (e.g. super-cooled glass and non-crystalline organic compounds or substances with cubic crystal lattices e.g. NaCl ) have single refractive index. Through this type of microscope the amorphous substances do not transmit light, and they appear black. They are called isotropic substances. Hot-stage microscopy In this case, the polarizing microscope is fitted with a hot stage to investigate polymorphism, melting points, transition temperatures and rates of transition at controlled rates. It facilitates in explaining the thermal behavior of a substance from the DSC and TGA curves

11. THERMAL ANALYSIS Differential Thermal Analysis In DTA instrument a record is produced where temperature difference (  T) (between the sample and reference material) is plotted against temperature (T) when two specimens are subjected to an identically controlled temperature regime. The reference material is alumina, keiselguhr .

12. Differential Scanning Calorimetry In DSC method the difference in energy inputs (  H) into a sample and reference material is measured as a function of temperature as the specimens are subjected to a identically controlled temperature programme . Samples that may be studied by DSC or DTA are: Powders, fibres , single crystals, polymer films, semi-solids or liquids.

13. Thermogravimetric Analysis (TGA) Application of TGA in preformulation study Desolvation and decomposition processes are monitored. Comparing TGA and DSC data recorded under identical conditions can greatly help in the explanation of the thermal process.

14. X-RAY POWDER DIFFRACTION When a X-ray beam falls on a powder the beam is diffracted. This diffraction in found only in case of crystalline powder. Amorphous forms do not show X-ray diffraction.

15. ATOMIC FORCE MICROSCOPY Atomic force microscopy  ( AFM ) or  scanning force Microscopy  ( SFM ) is a very-high-resolution type of  scanning probe microscopy (SPM), with demonstrated resolution on the order of fractions of a  nanometer , more than 1000 times better than the  optical diffraction limit

16. Applications: The AFM has been applied to problems in a wide range of disciplines of the natural sciences, including  solid-state physics , semiconductor science and technology,  molecular engineering ,  polymer chemistry  and  physics ,  surface chemistry ,  molecular biology ,  cell biology , and  medicine .

17. Hygroscopicity Many pharmaceutical materials have a tendency to adsorb atmospheric moisture (especially water-soluble salt forms). They are called hygroscopic materials and this phenomenon is known as hygroscopicity Tablets containing dry  herbal  extracts are highly  hygroscopic , requiring a protective coating against moisture. ethylcellulose ( Ethocel Premium Standard-7) and derived basic polymethacrylic acid are able to improve stability of herbal extract

18. Tests of hygroscopicity Procedure: Bulk drug samples are placed in open containers with thin powder bed to assure maximum atmospheric exposure. These samples are then exposed to a range of controlled relative humidity (RH) environments prepared with saturated aqueous salt solutions . The amount of moisture adsorbed can be determined by the following methods: ( i )     Gravimetry (ii)    Thermogravimetric analysis (TGA) (iii)  Karl-Fischer titration (KF-titration) (iv)  Gas chromatography (GC)

19. Significance of hygroscopicity test To decide special handling procedure (with respect to time). To decide ( i ) the storage condition i.e. at low humidity environment. (ii) special packaging – e.g. with desiccant. (c) Moisture level in a powder sample may affect the flowability and compactibility which, are important factors during tableting and capsule filling. After adsorption of moisture, if hydrates are formed then solubility of that powder may change affecting the dissolution characteristics of the material. Moisture may degrade some materials. So humidity of a material must be controlled.

20. Fine particle characterization Parameters those are measured: ( i )   particle size and size-distribution (ii)  shape of the particle (iii) surface morphology of the particles Instrumental methods of particle size characterization Light microscope Stream counting devices Sieve method

21. (a ) Light microscope First a  standard graticule  (BS 3625) is standardized with a  stage micrometer . Then small number of particles are spread over a glass slide and placed on the stage of the microscope. Particles are focussed and the particle diameters are measured. Several hundred particles are measured and reported as a histogram. Disadvantage : The procedure is time consuming. (b ) Stream counting devices Examples:(a) Coulter counter:electrical sensing zone method (b) Malvern particle & droplet size Laserdiffraction (c) HIAC – counter       – optical sensing zone method (c) Sieve analysis A powder sample is passed through a standard sieve set. The particle size is plotted against % weight retained on each sieve. Use : This method is used generally for large samples

22. Instrumental method for determination of specific surface area Brunauer , Emmett and Teller (BET) nitrogen adsorption method A layer of nitrogen molecules is adsorbed to the sample surface at –196 C. Once the surface is saturated, the sample is heated to room temperature, the nitrogen gas is desorbed, and its volume is measured and converted to the number of adsorbed molecules via the gas law. Since each N 2 molecule occupies an area of 16 A 2 , one may readily compute the surface area per gram of each pre-weighed sample Instrumental method for characterization of surface morphology The scanning electron microscope creates the magnified images by using electrons instead of light waves.

23. Powder flow properties Powder flow properties depends on particle size Density Shape electrostatic charge and adsorbed moisture A free-flowing powder may become cohesive during development. This problem may be solved by any of the following ways : 1. by granulation 2. by densification via slugging 3. by filling special auger feed equipment (in case of powder) 4. by changing the formulation

24. SOLUBILITY

25. SOLUBILITY ANALYSIS Solubility depends on: pH & pKa Temperature Ionic strength Buffer concentration Determination of equilibrium solubility of a drug The drug is dispersed in a solvent. The suspension is agitated at a constant temperature. Samples of the suspension are withdrawn as a function of time, clarified by centrifugation, and assayed to establish a plateau concentration.

26. 1.Determination of pka value When a weakly acidic or basic drug partially ionizes in GI fluid, generally, the unionized molecules are absorbed quickly. Handerson-Hasselbach equation provides an estimate of the ionized and unionized drug concentration at a particular pH . Method of determination of pKa of a drug Detection of spectral shifts by UV or visible spectroscopy at various pH Potentiometric titration Variation of solubility at various pH

27. Effect of temperature on solubility Heat of solution,  H S represents the heat released or absorbed when a mole of solute is dissolved in a large quantity of solvent. Significance: Most commonly, the solubility process is endothermic, e.g. non-electrolytes, unionized forms of weak acids and bases   H is positive  Solubility increases if temperature increases. Solutes that are ionized when dissolved releases heat  the process is exothermic   H S is negative  Solubility increases at lower temperature.

28. Solubilization There is a need to understand the possible mechanism of solubilization of a drug molecule over the pH range encountered in GIT to achieve stable dosage form with effective absorption and enhanced bioavailability Means of increasing the solubility are: ( i ) Addition of a cosolvent to the aqueous system e.g. ethanol, propylene glycol and glycerin. MOA : These co-solvents disrupt the hydrophobic interactions of water at the non-polar solute / water interfaces. (ii) Solubilization in micellar solutions such as 0.01 M Tween 20 solution. (iii) Solubilization by forming molecular complexes e.g. benzoic acid forms complex with caffeine

29. Partition coefficient Partition coefficient is defined, as the ratio of un-ionized drug concentrations between the organic and aqueous phases, at equilibrium K O/W = [ C oil / c water ] Generally , octanol and chloroform are taken as the oil phase Significance : Drug molecules having higher K O/W will cross the lipid cell membrane To select the appropriate extraction solvents , carrying out drug stability studies, absorption of drug from dosage forms

30. DISSOLUTION This study enables us to study the influence of particle size, surface area, and excipients on dissolution of candidate drug molecule It also enables , if dissolution is the rate limiting step in the absorption process of a drug substances The extent of the drug absorption into systemic circulation depends on their dissolution rates in case of dosage form such as tablet, capsule, and suspension as well as those administered intramuscularly in form of pallets or suspension

31. The dissolution rate of a drug substance in which surface area is constant during disintegration is described by the modified Noyes-Whitney equation: dc/ dt = DA/ hV ( C s – C ) Where, D = diffusion coefficient of the drug in the dissolution medium h = thickness of the diffusion layer at the solid/liquid interface A = surface area of drug exposed to dissolution medium. V = volume of the medium C S = Concentration of saturated solution of the solute in the dissolution medium at the experimental temperature. C = Concentration of drug in solution at time t.

32. When A = constant and C S >> C the equation can be rearranged to : dC / dt = DA/ hV *C s ‘or’ VdC / dt = DA/h * C s ‘or’ W=k At where , k= D/h where, W = weight (mg) of drug dissolved at time t k = intrinsic dissolution rate constant

33. Determination of k: Pure drug powder is punched in a die and punch apparatus to give a uniform cylindrical shape. The tablet is covered with wax in all sides. One circular face is exposed to the dissolution medium. Thus, as dissolution proceeds, the area, A, remains constant. Time to time dissolution medium is taken out and fresh medium added to the chamber . With two types of assembly, the experiments can be carried out .

34. STABILITY ANALYSIS

35. Stability analysis Preformulation stability studies are the first quantitative assessment of chemical stability of a new drug . This may involve: Stability study in toxicology formulation Stability study in solution state Stability study in solid state 1.Stability study in toxicology formulation A new drug is administered to animals through oral route either by: Mixing the drug in the feed I n the form of solution I n the form of suspension in aqueous vehicle

36. Feed may contain water, vitamin, minerals (metal ions), enzymes and different functional groups that may severely reduce the stability of the new drug. So stability study should be carried out in the feed and at laboratory temperature . For solution and suspension, the chemical stability at different temperature and pH should be checked For suspension-state the drug suspension is occasionally shaken to check dispersibility

37. 2.Solution Stability Stability of a new drug may depend on : pH ionic strength co-solvent (iv) light ( v) temperature 3. Solid state stability Identification of stable storage conditions for drug in the solid state and identification of compatible excipients for a formulation

38. 4.Drug-excipient stability profile Hypothetical dosage forms are prepared with various excipients and are exposed to various conditions to study the interactions of drug and excipients

39. DRUG-EXCIPIENT COMPATIBILITY STUDIES

40. INTRODUCTION Drug- excipient compatibility studies represent an important phase in drug development. Drug substances are usually combined with excipients which serve different and specialized purpose. Although excipients are pharmacologically inert, they can undergo chemical reactions and physical interactions with drug substances under favorable environmental conditions. These interactions can lead to instability resulting in the formation of new entities with different physicochemical properties and pharmacological effects. Drug- excipient compatibility studies have been used to obtain rapid stability assessment of drug and excipients , drug stability are investigated under the stress condition according to standard protocol and/or existing knowledge on potential degradation pathway or incompatibilities.

41. Mechanism of Drug- Excipient (s) interactions

42. a. Physical drug- excipient interactions: Physical interactions may result in changes in dosage uniformity, color, odor, flow properties, solubility, sedimentation rate, dissolution rate etc. Incompatibilities are assessed by physically observing the test samples. Physical interactions can be either beneficial or detrimental to the product performance depending on its application b. Chemical drug- excipient interactions This involves the interaction of drug substance and excipient through chemical degradation pathway. Chemical interactions can be in the form of hydrolysis, oxidation, racemization , polymerization, Maillard reactions, photolysis etc., and changes in the study samples are analyzed by a chromatographic-based assessment of potency and formation of degradants or by any other analytical method depending on the nature of the candidate drug molecule. c. Physiological/Biopharmaceutical drug- excipient interactions Those interactions that occur after the drug product has been administered to the patient. These interactions are similar to physical interactions but differs in the sense that The interaction is between the medicine (drug substance and excipients ) and the body fluids The interactions have the tendency to influence the rate of absorption of the drug

43. Analytical Methods for Drug – Excipient Incompatibility Thermal methods of analysis – DSC- Differential Scanning Calorimetry – DTA- Differential Thermal Analysis Accelerated Stability Study DRS-Diffuse Reflectance Spectroscopy Chromatography – SIC-Self Interactive Chromatography – TLC-Thin Layer Chromatography – HPLC-High Pressure Liquid Chromatography Miscellaneous – Radiolabelled Techniques – Vapour Pressure Osmometry – Flourescence Spectroscopy

44. Thermal Techniques: Differential Scanning Calorimetry (DSC) DSC is widely used to investigate and predict any physicochemical interaction between drug and excipients involving thermal changes. METHOD -The preformulation screening of drug- excipient interaction requires (1: 1) Drug:excipient ratio, to maximize the likehood of observing an interaction. -Mixture should be examined under N 2 to eliminate oxidative and pyrrolytic effects at heating rate ( 2, 5 or 100 c / min) on DSC apparatus

45. Differential Thermal Analysis Thermal Analysis is useful in the investigation of solid state interactions. It is also useful in the detection of eutectics. Thermograms are generated for pure components and their physical mixtures with other components. In the absence of any interaction, the thermograms of mixtures show patterns corresponding to those of the individual components. In the event that interaction occurs, this is indicated in the thermogram of a mixture by the appearance of one or more new peaks or the disappearance of one or more peaks corresponding to those of the components. Example:DTA (DRUG:ENALAPRILMALEATE)

46. 2. ACCELARETED STABILITY STUDY Different formulations of the same drug are prepared. Samples are kept at 40ºC / 75 % RH. Chemical stability is assessed by analyzing the drug content at regular interval. Amount of drug degraded is calculated. % Drug decomposed VS time(month) is plotted.

47. DIFFUSE REFLECTANCE SPECTROSCOPY Principle: “Penetration of a portion of incident radiation flux into the interior of the solid sample, return of some portion of radiation to the surface of sample following partial absorption and multiple scattering at boundary of individual sample particles.” • Detects the decomposed products, along with physical and chemical adsorption of excipients on to A.P.I. and vice versa. • Example: Ethanol mediated interaction between dextroamphatamine sulphate and spray dried lactose in solid–solid mixture. • Discoloration of powdered mixture was accelerated by secondary amine and by storage at elevated temp. Two new absorption maxima were observed at 340 nm & 295 nm respectively

48. SELF INTERACTIVE CHROMATOGRAPHY SIC is useful for proteinous drug and excipients . METHOD:- -SIC is a modified type of affinity chromatography. - Here,drug is made immobilized as the stationary phase & solution to be tested( excipient soln.) acts as mobile phase -Measure Rt (Retention time) & compare with non –retained marker PRINCIPLE: - For different mobile phases (i.e. different excipients ) the injected drug have different interactions (may be repulsive or attractive) with the stationary phase of drug leads to shift in retention time ( Rt ). A. When interaction is repulsive,a sharper peak is obtained at a shorter retention time B. When no net interaction between the immobilized drug,Rt =dead volume of column C. When attractive interactions,it will have longer retention time& wider peak

49. TLC AND HPTLC TLC is generally used as confirmative test of compatibility after performing DSC. S.P. consist of powder (Silica, Alumina, Polyamide, Cellulose & Ion exchange resin) adhered onto glass, plastic or metal plate. Solution of Drug, Excipient & Drug: Excipient mixture are prepared & spotted on the same baseline at the end of plate. The plate is then placed upright in a closed chamber containing the solvent which constitutes the M.P. Any change in the chromatograph such as the appearance of a new spot or a change in the Rf values of the components is indicative of an interaction. The technique may be quantitated if deemed necessary. If significant interaction is noticed at elevated temperatures, corroborative evidence must be obtained by examining mixtures stored at lower temperatures for longer durations. Among the advantages of thin-layer chromatography in this application are: -Evidence of degradation is unequivocal. -The spots corresponding to degradation products can be eluted for possible identification.

50. HPLC AND FLUORESCENT MEASUREMENT • HPLC (high pressure liquid chromatography) Characteristics: - -The APIs and model compounds of diversified chemical structure was studied. -Elution rate: 7.5 ml/hr at ambient temp. -Allows the detection and quantification of impurities, which span a wide range of polarities, including nonpolar compounds. • FLUORESCENT MEASUREMENT : -This technique is restricted to those compounds, which can generate florescence. As the no. of such compounds are restricted, this method is used in Analysis and not in preformulation .

51. 6. Miscelleneous method: A) VAPOR PRESSURE OSMOMETRY & EQUILIBRIUM DIALYSIS: Principle : ‘samples of solutions and pure solvent are introduced into a temperature-controlled enclosure, which is saturated with solvent vapor.Since the vapor pressure of solution is lower than that of solvent, solvent vapor condenses on solution sample causing its temperature to rise. The temperature rise is predicted by Clausis – Clapcyron equation.’ Characteristics: -Either liquid or solid sample and must be soluble in organic solvent or in water -Sample must not undergo association in solution. -Sample size is approx. 3 gm for multiple analysis. -Measures a no. of avg. mole. Wt. of about 10,000 Daltons. -This method measures interactions & records the interaction caused by variation of particle no.   B) RADIO LABELLED TECHNIQUES: -It is important when the API is having radioactivity. -Method is carried out by using either 3H or 13C. -Highly sensitive method but the cost of carrying out the method & the availability of well established other techniques & methods, this method is generally not preferred.

52. POSSIBLE INTERACTIONS BETWEEN CHEMICALS AND HERBS Drugs can interact in two ways

53. Pharmacokinetic mechanism of drug interaction Alterations of absorption i.e. slippery elm — reduces absorption of thyroxine (helps to regulate metabolism) & lithium (a mood stabiliser ): Changes in the gastrointestinal pH (i.e. changing the stomachs acid environment which can affect how much of a medicine is absorbed). Adsorption, chelation and other complex‘s (i.e. two products combining and affecting the solubility or absorption). Charcoal – is used for overdoses by this process to adsorb drugs. Changes in Gastro intestinal motility (how quickly a drug passes through the system). Protein binding – This can affect how much of a drug is available for absorption. Horse chestnut binds with plasma and tissue proteins and competes against warfarin , a medicine used to prevent blood clots. Changes in metabolism and elimination resulting in either increasing or decreasing the amount of drug available to have an effect: The interaction may involve a herb causing either an increase or decrease in the amount of drug in the blood stream. A decrease in the amount of drug could occur by herb components binding the drug and preventing it from getting into the blood stream from the gastrointestinal tract. A decrease in a drug could be by stimulating the production and activity of enzymes that degrade the drug and prepare it for elimination from the body. A decrease in drug dosage by virtue of an interaction could make the drug ineffective. An increase in drug dosage could make it reach levels that produce side effects.

54. Pharmacodynamic mechanism of drug interaction Alterations in the way a drug affects a tissue or organ system. These interactions result in either enhancing or antagonising effects. Change in first pass metabolism (the way the liver processes a drug) e.g. St John‘s Wort acts as an inducer of the liver enzyme system. This is responsible for the metabolism of a large number of drugs, therefore may see an accelerated metabolism and reduced plasma concentrations of various drugs. Grapefruit juice – inhibits a transport protein that acts as a pump to move drugs across the cell wall, which can lead to higher levels of many drugs.

55. Examples of drug and herbs interaction Digoxin  (controls heart rate), some preparations with laxative effect (aloe, liquorice ) decrease potassium and increase digoxin toxicity. Theophylline  (eases breathing), any preparation that has stimulant effects i.e. caffeine (including guarana ) may have additive central nervous system effects and increase theophylline levels. Herbal products with a diuretic effect (including caffeine products) a problem for patients on lithium which helps to stabilise mood. Warfarin  (prevents blood clots), increased risk of bleeding with products that have a coumarin component (black cohosh , chamomile) or antiplatelet effects ( billberry leaf, fish oil, vitamin E and ginger, garlic), cranberry.

56. St John’s Wort  and certain antidepressants, can cause ‘serotonin syndrome’ a serious condition marked by confusion, uncoordination , and cardiovascular irregularities.St John’s Wort and sunlight can cause photosensitivity, especially if combined with other photosensitizing drugs like certain antibiotics.In addition, fatigue and gastrointestinal upset occur in some people. Avoid standardized St. John’s Wort if you use tanning beds or take drugs that cause photosensitivity Kava & Sleeping tablets  – increases sedation leading to coma.Kava Kava has become the herbal answer to Valium in America. Kava helps calm the mind and relax the muscles without causing side effects like over-sedation or addiction. However, kava is not safe for everyone. Don’t take kava with alcohol as it can intensify the effects of alcohol. In addition, kava may interact with anti-anxiety medications like, benzodiazepines and anaesthetics . Kava should also be avoided by people taking anti-psychotic drugs and levodopa for Parkinson’s disease. Gingko & Aspirin  – increases inhibition of platelet aggregation (a blood component) leading to increased bleeding, bruising (Gingko can be used for vascular insufficiency, poor circulation, stress and tinnitus. It is also a neroprotective and antioxidant, helps to improve concentration). St John’s Wort & Digoxin  – reduces absorption of digoxin leading to decreased digoxin level. Garlic & Warfarin –  increases inhibition of platelet aggregation leading to increased bleeding, bruising (Garlic for high cholesterol and blood pressure).

57. Reference http://pharmapproach.com/drug-excipient-compatibility-studies/ http://www.itmonline.org/arts/herbdrug.htm http://www.chiro.org/nutrition/FULL/Drug_Herb_Interactions.htm Lachman and lieberman’s ‘The theory and practices of Industrial Pharmacy’ 4 th edition, CBS publishers and distributors, page no: 217-252