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)

3. • 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
• Studies 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
Organoleptic
characters
color
odor
flavor
Bulk Characterization
Crystallinity and
polymorphism
Hygroscopicity
Particle
characterization
Powder flow
Solubility analysis
Ionization constant-
pKa value
pH solubility profile
Thermal effects
Common ion effect –
KSP
Dissolution
Partition coefficient
Solubilization
Stability analysis
Stability in toxicology
formulation
Solution stability
Solid state stability

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

8. Bulk Characterization
Crystallinity
It has marked effect on its hardness, density, transparency and diffusion.
Which influences both the choice of delivery system and activity(rate of
delivery)
• Crystalline state: Selenite crystals, also known as Gypsum Fibrosum or
Shi Gao in Pinyin, is not only a plaster building material, but also one of
commonly used Chinese herbs
• Amorphous state: do not have any fixed internal structure. E.g. Cardiac
glycosides
Polymorphism
• When a substance exists in more than one crystalline form, the various
forms are called Polymorphs and the phenomenon as polymorphism
• An example for herbal medicine is licorice- associated hypertension,
which is thought to be caused by increased renal sodium retention

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
1. Light microscope
2. Stream counting devices
3. 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 –
1960C. 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 N2 molecule occupies an area of 16 A2, 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
1. particle size
2. Density
3. Shape
4. 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

25. SOLUBILITY ANALYSIS
• Solubility depends on:
1. pH & pKa
2. Temperature
3. Ionic strength
4. 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.
Conc.
Time
Plateau
Equilibrium
solubility conc.
Fig. 1

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
1. Detection of spectral shifts by UV or visible spectroscopy at various pH
2. Potentiometric titration
3. Variation of solubility at various pH

27. Effect of temperature on solubility
• Heat of solution, HS 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  HS 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
KO/W = [ Coil / cwater ]
• Generally, octanol and chloroform are taken as the oil
phase
Significance:
• Drug molecules having higher KO/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 ( Cs – 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
CS = 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 CS >> C the equation can be
rearranged to :
dC/dt = DA/ hV*Cs ‘or’ VdC/dt = DA/h * Cs ‘or’ W=k At
where, k= D/h
• where,
W = weight (mg) of drug dissolved at time t
k = intrinsic dissolution rate constant
Slope = kA
time (t)
W

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.
.. .. ... ..
.. .. ... ..
Static disc
dissolution
aparatus
Rotating disc
dissolution
apparatus

35. Stability analysis
• Preformulation stability studies are the first
quantitative assessment of chemical stability of a new
drug. This may involve:
1. Stability study in toxicology formulation
2. Stability study in solution state
3. Stability study in solid state
1.Stability study in toxicology formulation
A new drug is administered to animals through oral
route either by:
I. Mixing the drug in the feed
II. In the form of solution
III. In 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:
(i) pH
(ii) ionic strength
(iii)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

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
Physical drug-excipient interactions
Chemical drug-excipient interactions
Physiological/Biopharmaceutical drug-
excipient 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 N2 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
Pharmacokinetically
Pharmacodynamically

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