Добавил:
Sekretar
kiopkiopkiop18@yandex.ru
t.me/Prokururor I Вовсе не секретарь, но почту проверяю
Опубликованный материал нарушает ваши авторские права? Сообщите нам.
Вуз:
Предмет:
Файл:Ординатура / Хирургия / Библиотека им академика М.И. Перельмана / Книга_5441_Библиотеки_им_академика_М_И_Перельмана.pdf
383
The advancement in polymer chemistry has provided large numbers of biocompat-
ible and biodegradable polymers. The lipidic nanoparticles can be further classied
as solid lipid nanoparticles, nanostructured lipidic carriers, liposomes, niosomes,
etc. Recently, some formulation scientists have also published articles on hybrid
nanoparticles prepared using lipids and polymers to improve biocompatibility and
permeation and control drug release (Jain and Zhong 2022). Chemically herbal
medicines are more prone to degradation by extreme pH and enzymes present in the
human body. To protect herbal medicine from the harsh biological environment of
the human body, encapsulating them inside the nanocarriers is the best way to
improve their bioavailability and therapeutic response (Jain etal. 2014). Multiple
articles published in the last decade proved the importance of nanoparticles in the
delivery of herbal medicine.
The chief bioactive component of Curcuma longa is curcumin, which has been
linked to several health benets, including anti-inammatory, anticancer, and anti-
oxidant properties. Despite this, it showed signicantly low water solubility, which
makes it less bioavailable and, thus, limits its use in clinical application. To over-
come this, Xie etal. (2011) formulated PLGA nanoparticle formulation of curcumin
using the solvent evaporation method to improve its oral bioavailability. The results
demonstrated a 5.6-fold increase in oral bioavailability and a roughly 640-fold
increase in water solubility with curcumin-loaded nanoparticles in comparison to
curcumin powder (Xie etal. 2011). Furthermore, the diterpenoid class of chemicals
such as andrographolides discovered from Andrographis paniculata is known for its
anticancer activity. Andrographolides show poor water solubility, which result in
poor bioavailability. To increase its solubility and bioavailability, Praveen etal.
(2013) synthesized solid lipid nanoparticles using the solvent injection method and
tested for invitro cell viability against the hormone-positive breast cancer cell line
(MCF-7 cells). The results showed the desired safety and activity prole (Parveen
etal. 2014). Hence, various types of polymeric and lipidic nanoparticles are the best
choice for delivering herbal medicines without any toxicity and stability issues.
15.2.3 Herbal Hydrogels
Hydrogels are three-dimensional polymeric networks of hydrophilic monomers,
which have a high water-retention capacity. Hydrogels can be engineered to have
mechanical properties that closely resemble various soft biological tissues and often
show great biocompatibility (Ho etal. 2022). Moreover, their exible and soft tex-
ture reduces the inammatory responses of surrounding cells and tissues. Hydrogels
can be categorized as natural, synthetic, or hybrid, based on the polymers used in
formulating the hydrogel. The size of the holes in the hydrogel network may also be
changed based on the need of particular formulation, which is an important factor
and directly associated with the drug release from the hydrogel. Hydrogels can also
be prepared by conjugating two or more polymers to get the desired properties
(Bashir etal. 2020). One such approach includes formation of pH-sensitive bond
between polymers, which releases the drug quickly at a particular pH.For instance,
15 Herbal Formulations: Development, Challenges, Testing, Stability, and…
384
a pH-responsive hydrogel for transdermal delivery of naringenin was developed by
Park and coworkers using radical polymerization of carboxymethyl cellulose and
2-hydroxyethyl acrylate. This gel showed a signicantly higher swelling ratio at the
pH of acne-prone skin and atopic skin (pH7–8) compared to the pH of normal skin
(pH5.5), due to ionization of the carboxyl group at alkaline pH.Further, skin per-
meation of naringenin was also greatly increased, when topically administered
through hydrogel (Park etal. 2018). Thus, hydrogel showed great potential for topi-
cal delivery of herbal medicine attributed to its high drug-loading capacity, easy
preparation method, and great compatibility with herbal medicines.
The research publications published in the last decade prove that nanotechnology
is an efcient way to deliver herbal medicines. The wide range of nanocarriers can
solve the problems of herbal medicines like poor solubility, low potency, poor sta-
bility, lack of compatibility, etc. Figure15.1 shows the schematic representation of
challenges associated with herbal formulation development and strategies to over-
come these challenges for successful preparation of herbal nanoformulations.
Overall, nanotechnology has great potential to bypass the pitfalls of herbal medi-
cine. We have discussed the testing methodologies, challenges of nanotechnology,
and regulatory requirements for marketing approval ofherbal nanoformulations in
the subsequent sections.
15.3 Challenges intheDevelopment ofHerbal Formulations
The development of herbal formulation is comparatively more challenging than the
formulation development with synthetic drugs. Herbal medicine is more prone to
degradation by change in temperature, pH, and solvent. Further, herbal medicines
Fig. 15.1 Schematic representation of limitations and strategies to overcome these limitations for
development of herbal nanoformulations
S. R. Pawar et al.
385
are comparatively less explored drug molecules; hence deciding the effective dose,
compatibility, stability, degradation prole, etc. demands scientically sound
knowledge to formulate any dosage form containing therapeutically effective dose.
Some commonly encountered challenges for formulation scientists during the
development of herbal formulations are discussed in the following subsections.
15.3.1 Extraction ofDesired Herbal Compound
The herbal extracts obtained immediately after the primary extraction are usually a
mixture of several phytoconstituents of varied molecular weight, medicinal poten-
tial, solubility, and chemical classes. Few are hydrophilic like glycosides, polyphe-
nolics, etc., others are lipophilic, such as diterpene, tri-terpenoids, monoterpene,
sesquiterpene, etc., while some may be median polar with partial aqueous as well as
lipid solubility like alkaloids, avonoids, etc. Altogether, these dissimilarities create
challenges for scientists in the characterization of herbal medicines and nanoformu-
lation, which can be solved by bioassay-guided fractionation of these extracts
(Bairwa and Jachak 2015). This technique segregates each phytoconstituent, start-
ing from solubility-based differentiation, followed by its separation based on polar-
ity using the chromatographic techniques and screening of molecules.
15.3.2 Difficulties inCrossing Biological Barriers
Any pharmacologically active moiety going inside the body must cross one or more
biological barriers before exerting the therapeutic response based on the route of
administration and site of action (Wu etal. 2020). Herbal medicines and formula-
tions are comparatively less stable in biological systems than synthetic and semi-
synthetic therapeutically active moieties (Banerjee etal. 2018). Hence, delivering
herbal medicine at the site of action requires detailed knowledge of formulation
development and associated biological interaction. Here, nanotechnology-based
approach may provide superior results in protecting herbal medicines.
15.3.3 Higher Cost ofPreparation
Nanotechnology is itself a costly technology due to the requirement to maintain
very high-quality standards, high-end technical instruments, technically sound sup-
port staff, and cleanrooms (ISO 4 or Class 10) to manufacture nanoparticles. Herbal
nanomedicine again adds on signicant amount of cost due to its additional require-
ment of extraction, identication, and purication steps (Pathak and Thassu 2009).
Purication of herbal extract is itself a humongous task, which requires very high-
end instruments like nuclear magnetic resonance spectroscopy, liquid
chromatography- mass spectrometry (LCMS), high-performance thin-layer chroma-
tography (HPTLC), supercritical uid chromatography (SFC), inductively coupled
15 Herbal Formulations: Development, Challenges, Testing, Stability, and…
386
plasma-mass spectroscopy (ICP-MS), and many more (Banerjee et al. 2018).
Overall, the extraction of pure herbal medicine and preparation of herbal nanopar-
ticles are high-cost processes.
15.3.4 Physical Stability ofHerbal Formulations
Physical stability is the key property of any formulation required to maintain the
efcacy and safety prole during its clinical application. Herbal medicine and for-
mulations are very sensitive to changes in temperature, pH, light exposure, and
humidity (Jeevanandam etal. 2016). Any alteration in abovementioned parameters
can cause the generation of degradation products and may alter the pharmacological
activity of herbal medicines (Wu et al. 2011). These changes are most likely to
occur during transportation or due to improper storage, although the probability of
occurring physical instability are less due to the regulatory guidelines, which made
the detailed stability study mandatory for herbal formulations.
15.3.5 Toxicity ofHerbal Medicine
Herbal formulations are also associated with different toxicity concerns like non-
IgE- mediated hypersensitivity or pseudo-allergic reactions, which may cause ana-
phylactic shock, face swelling, cardiac distress, ushing, etc. (Hua etal. 2018).
Therefore, it is advisable to deeply investigate the safety prole by relevant exvivo
and/or in vivo assays of potential toxicities and adverse effects before clinical
approval of herbal formulations (Desai 2012). Further, detailed invivo toxicity and
degradation kinetics studies in relevant animal models should also be carried out to
evaluate the short-term and long-term toxicity and biocompatibility of herbal medi-
cines and formulations.
These are some of the challenges that researchers may face during the develop-
ment of herbal formulations. Further, the testing methods to evaluate the purity and
stability of herbal medicines are discussed in the next section.
15.4 Testing ofHerbs andHerbal Formulations
The phytochemicals found in herbal plants showed variability based on factors such
as climate, soil composition, and geographical condition; these variations impede
the process of standardization (Nazim etal. 2018). The increasing growth in defor-
estation is the cause of the adulteration and substitution of natural medications,
which compromise the therapeutic potential of herbal medicines. Thus, it became
almost important to ensure the quality of medicinal herbal products by applying the
appropriate standards and sophisticated quality control techniques (Marchese etal.
2017). Standardization is important for the identication, evaluation, and purity of
herbal medicine as well as the verication of herbal products. The physical,
S. R. Pawar et al.
387
chemical, biological, and preliminary identication characteristics contribute to the
purity of herbal medicine and formulations. The quality and freshness of the herbal
drugs are determined by their purity (Rashid etal. 2018).
The pharmacognostical scheme for separation, macroscopic evaluation (shape
and markings), microscopic evaluation (qualitative and quantitative), evaluation of
physicochemical parameters (moisture content, acid insoluble ash, water soluble
ash, etc.), identications (adulterants and genuine drug), and other parameters
reported for the rst time can all be important tools for the authentication of herbal
medicine (Zhang etal. 2012). This process of standardization of formulation under
the standard setting of herbal medicines helped to create a monograph in the phar-
macopeia and other standard texts (Fernandes and Salgado 2016). The components
of herbal medicines are complex; hence certain high-end approaches and tactics are
used to verify the quality, purity, and integrity of the herbal formulations, which are
discussed in the following subsections.
15.4.1 Thermal Analysis
Thermal analysis is an analytical method widely used for the characterization of
herbal medicine such as the determination of purity, thermal stability, compatibility
with other phytocompounds and excipients, etc. (Guimaraes etal. 2017). Thermal
techniques (such as thermogravimetric analysis and differential thermal analysis)
can be used to analyze reaction order (n), activation energy (Ea), frequency factor
(A), and degradation constant of the herbal extract. These thermal approaches can
also be used to evaluate the absolute water content, crystallizationstate, and thermal
degradation (Liu etal. 2019a). Usingthermal analytical techniques like differential
thermal gravimetry and differential scanning calorimetry, the interaction between
the excipients and therapeutically active herbal medicine can be studied, which is
one of the important parameter in marketing approval of herbal medicine and
formulations.
15.4.2 High-Performance Thin-Layer Chromatography (HPTLC)
Extraction of herbal medicine is the inevitable step in the development of any herbal
formulation. During the process of extraction, active compounds are frequently
present in the extraction media with other similar components (Do etal. 2019).
Here, HPTLC is used to get a ngerprinting prole as a primary quality control test.
Further, it is a widely approved qualitative method and used to match the pharma-
copeial standards of diverse medicinal herbal formulations (Patil etal. 2018). Using
the HPTLC scientists can determine the efcacy, safety, and quality of divulged
phytochemical components.
15 Herbal Formulations: Development, Challenges, Testing, Stability, and…
388
15.4.3 High-Performance Liquid Chromatography (HPLC)
The quantitative and qualitative separation and identication of different compo-
nents of phytocompounds are the most stringent step in the extraction of herbal
medicine. Thesophisticate technologies like preparative and semipreparative HPLC
methods are used in the separation of large samples of extraction with utmost accu-
racy and speed (Hamburger 2019). This technique separates the phytoconstituents
of similar chemical groups based on their polarity, hence providing the most accu-
rate separation (Walters etal. 2017). This technique is frequently employed in the
purication of herbal extracts.
15.4.4 Liquid Chromatography Mass Spectrometry (LCMS)
In complicated matrix analysis, where prior treatment of purication of the herbal
medicine is required to improve the quality and yield, the HPLC method has several
limitations when used alone without the assistance of additional methods. This
problem is solved by employing LCMS technology, which signicantly increases
the sensitivity of detection (Marchetti etal. 2019). The capabilities of the LCMS
technology include ner separation and a broad range of detection of analytical
chemicals, molecular mass, information of fragmentation, retention time, and struc-
ture characterization. The LCMS combination technique can be used for the identi-
cation, quantication, and quality control of marketed herbal products as well as
for the extraction of raw plant material. The ultra-high-performance liquid chro-
matogram coupled with electrospray ionization tandem quadrupole-time of ight/
mass spectroscopy (UHPLC-Q-TOF/MS) (Zhou etal. 2018) is a more powerful tool
for analysis that can be used to analyze complex traditional herbal extracts with
high resolution, efciency, and sensitivity.
15.4.5 Supercritical Fluid Chromatography
The SFC method uses compressed carbon dioxide (CO
2
) and a small proportion of
organic solvents, such as methanol, as the mobile phase. Here, the ratio of carbon
dioxide is higher compared to organic solvent; hence it is frequently referred to as
an alternative to the chromatographic method. In contrast to traditional organic sol-
vent methods, the SFC technique is used to extract the principal analytes from the
extraction media (Liu etal. 2019b). This technique can analyze frequently present
compounds in extraction media such as carbohydrates, alkaloids, saponins, avo-
noids, phenolics, lipids, etc. The capacity to identify and separate the fat-soluble
vitamins is an important advantage of SFC (Murcia-Morales et al. 2019). SFC
approachrequires a signicantly shorter time, utilizes fewer solventsand it is envi-
ronmentally friendly.
S. R. Pawar et al.
389
15.4.6 Gas Chromatography-Mass Spectrometry (GCMS)
GCMS is a powerful technique used to separate and subsequently identify the vari-
ous components of herbal extracts. The examination of volatile derivatives of herbal
extract is the most difcult to analyze by another sensitive analytical method.
Hence, GCMS is exclusively used to qualitatively and quantitatively analyze the
volatile oils present inside the herbal extracts (Zhang etal. 2018). It may also be
used to identify the various derivatives and drug metabolites of herbal medicines by
separating them from each other. LCMS is relatively more sensitive than GCMS,
hence the application of GCMS is limited to the analysis of volatile molecules
(Saito etal. 2019). The non-volatile and/or thermolabile components are not suit-
able for GCMS analysis.
15.4.7 Inductively Coupled Plasma-Mass Spectroscopy
Elemental components present inside the herbal medicines are an essential part of
human dietary requirements, although the excess amount of elemental components
can cause unwanted side effects to the human body. The quantity of elemental com-
ponents present inside the plant varies with geological condition, rainfall, quality of
soil, and pH (Varhan Oral etal. 2019). Hence, regulatory authorities have decided
the certain limits for elemental components, and manufacturers should meet these
criteria to get marketing approval for herbal medicine and formulations. Elemental
components are generally present either in the ionic form or non-ionic form with or
without other phytoconstituents (Tokalıoğlu etal. 2019). To qualitatively and quan-
titatively identify these elemental components, technologies like ICP-MS and PIXE
(partially induced X-ray emission) are used at the industrial level (Kumar etal.
2019). High amount of elemental components in herbal formulations may cause
multiple side effects in the human body; hence its control in herbal medicine and
formulation is a must for long-term use in humans after marketing approval.
The testing methods discussed in this section are most commonly employed for
purity and stability study of herbal medicine. Further, testing methods such as par-
ticle size analysis, zeta potential, drug release study, stability study, etc. also need to
be performed to get regulatory approval for herbal formulations. In this section we
have focused mainly on analytical testing methods for herbal medicines, whereas
stability-associated problems and requirements of herbal medicines and formula-
tions are discussed in the next section of this chapter.
15.5 Stability Requirement inHerbal Formulations
Herbal medicines are capturing the attention of scientists of all over the world in
treatment of diseases of modern era due to its less toxic potential and multifaceted
activity in human body. The clearance of stability testing is a must for any herbal
medicine or formulation to get regulatory approval for its clinical application. The
15 Herbal Formulations: Development, Challenges, Testing, Stability, and…
390
stability study is intended to ensure that the herbal medicine and herbal product
remain within the prespecied parameters of identication, strength, quality, and
purity. The stability of herbal medicine or formulation may be dened as “herbal
medicine and excipients should be in a physically, chemically, biologically, and
microbiologically stable state for a dened period” (Pingale etal. 2008). Each ele-
ment, whether medically active or inactive, in a dosage form can affect stability.
Environmental conditions such as temperature, light, air (particularly oxygen, car-
bon dioxide, and water vapors), and humidity can affect stability of herbal medi-
cines and formulations. Further, factors such as particle size, pH, quality of water
and other solvents, type of container, and the presence of additional chemicals either
from contamination or intentional mixing of different substances can inuence the
stability (Heigl and Franz 2003). Natural phytochemicals are generally less stable in
biological environment; hence detailed stability study is mandatory for such herbal
formulations before clinical approval. Multiple reports have been published demon-
strating the stability problems of herbal formulations along with its resolution and
efcient strategies to mitigate the stability problems (Poetsch etal. 2006).
Herbal medicines can lose their potency or may convert into harmful chemicals
upon non-suitable storage or transportation due to degradation. Therefore, it is cru-
cial for the manufacturer of herbal medicine or products to offer sufcient data on
its long-term stability testing and degradation kinetic study to ascertain the stability
in various temperatures. Nanotechnology-based approaches for formulation devel-
opment of traditional herbal medicine can primarily address stability-related prob-
lems. Generally, herbal medicines degrade in the presence of enzymes, strong
antioxidant molecules, or pH changes. Nanocarrier simply encapsulates the herbal
medicine inside the core of chemically inert polymeric or lipidic material and pro-
tects the sensitive herbal medicines from harsh biological environments (Ahmad
etal. 2022). The different types of instability of herbal medicines are discussed below:
15.5.1 Physical Instability
The issue of physical instability in natural medicines is frequently brought on by
contaminants and packaging container reactions. The secondary metabolites of
plant and chemical composition are impacted by factors such as microbial contami-
nation and moisture content. Further, the herbal formulations containing volatile
active ingredients have drawback of becoming less active upon longer storage
period (Shinde etal. 2009). To avoid physical instability, quality packaging material
should be used with a proper closure system.
15.5.2 Environmental Conditions
Suitable environmental condition is a must for the cultivation of herbal plants.
Variations in rainfall, altitude, temperature, and soil in addition to distinct harvest-
ing techniques, collection time, and method can lead to signicant variations in
S. R. Pawar et al.
391
product quality, stability, and concentration of desired chemicals in herbal medi-
cines and formulations (Thakur etal. 2011). The frequent change in weather associ-
ated with global warming created the need of using innovative cultivation techniques
like hydroponics, vertical farming, etc. to improve the yield of herbal crop
production.
15.5.3 Chemical Instability
Herbal formulations are frequently degraded by crystallization, hydrolysis, enzy-
matic deterioration, oxidation, and chemical interactions with the excipients or
additives during storage. Two main elements that impact the quality and stability of
herbal products are moisture content and temperature. For every 10°C increase in
temperature, a chemical reaction multiplies by two to threefolds, which affects the
heat-labile phytoconstituents, whereas moisture adsorption by herbal medicines
speeds up degradation, as most of these medicines are prone to hydrolysis
(Kyriakoudi etal. 2021). The pace of chemical decomposition is also accelerated by
the presence of enzymes in the herbal product.
15.5.4 Complex Mixtures
The combinations of various ingredients obtained during the extraction process may
impart stability-related problems in herbal medicine or formulations as the shelf-
life, therapeutic activity, concentration, and consistency of such components may
vary (Wang et al. 2023). Hence, proper purication steps are needed to be per-
formed to protect the nal product from such problems. Further, a detailed compat-
ibility study is mandatory, when more than one active ingredients are incorporated
in a single herbal formulation.
15.5.5 Lack ofGood Manufacturing Practices
The unwanted interactions of active ingredients with the packaging material and the
use of poor-quality packaging material are potent causes of instability in herbal
medicine or formulations as these increase the moisture content above the critical
value and cause mold growth in natural products (Drago etal. 2020). Alkaloids,
glycosides, tannins, avonoids, and other active ingredients are found in large quan-
tities in herbal preparations, and each one has unique stability requirements; hence
the stability of herbal formulations differs from that of each of its constituent parts.
Therefore, the primary duty of the maker of herbal drugs is to ensure that the
product is safe for patients to use and has sufcient stability for long-term storage.
Further, the stability prole of natural medicines should be carefully determined
because herbal formulations are generally used incombination of multiple active
herbal ingredients. Stability is a must to improve patient compliance, create
15 Herbal Formulations: Development, Challenges, Testing, Stability, and…
392
long- term trust with patients, and get regulatory approval. The distinct regulatory
guideline created by various countries for marketing approval of natural medicine
and formulations has been discussed in the following section.
15.6 Regulatory Guidelines inApproval
ofHerbal Formulations
Global concerns about the safety of herbal medicines have led national health
authorities to create regulations aimed at ensuring their safe use. WHO launched a
worldwide survey in 2001 covering herbal medicine regulations in 191 member
countries. The most crucial elements for the regulation of herbal medicines are
found to be the availability of research data, associated regulatory mechanisms, and
education (World Health Organization 2024a).
Herbal medicine regulations in India are handled by the Department of Ayurveda,
Yoga and Naturopathy, Unani, Siddha, and Homoeopathy (AYUSH), which was
founded in 1995 under the Ministry of Health and Family Welfare. The 1940 Drugs
and Cosmetics Act establishes the regulations governing the manufacturing and dis-
tribution of Ayurvedic, Siddha, and Unani (ASU) pharmaceuticals. The good manu-
facturing practices for ASU medications are particularly addressed in Schedule T of
the Drug and Cosmetics Act (US Food and Drug Administration 2024). In the USA
herbal remedies are subjected to United States (US) regulations under the botanical
drug product (21 CFR sections 331–358). These can be sold in the USA as an autho-
rized NDA or ANDA or as over-the-counter medication. In the USA, to include the
botanical component as a new active ingredient in the monograph, the company
would have to le a petition in line with 21 CFR 10.30.
Mexico, Brazil, and Argentina are the main competitors in the herbal market in
the region of Latin America. Brazil has regulated herbal drugs since 1967, and
herbal remedies are available as over-the-counter products and through prescrip-
tion. The Brazilian Drug Division, which oversees the enforcement of drug regula-
tions, published Directive 6in 1995, which outlined the legal requirements for
phytopharmaceutical drug registration in Brazil. In 2004, the RDC/48/2004 rule
was released in its fourth iteration. The directive states that registration of phyto-
pharmaceutical products is granted upon full verication of safety, efcacy, and
consistently dened quality. Further, human efcacy and safety test ndings are
also necessary for the registration of herbal medicine in Brazil (Sahoo etal. 2010).
Globally, there is an urgent need to develop a standard procedure for the develop-
ment of herbal medicinesincluding interlinking of the monographs for herbal medi-
cines published by various regulatory authorities, such as the Ayurvedic
Pharmacopoeia of India, United States Pharmacopoeia, British Herbal
Pharmacopoeia, Chinese Pharmacopoeia, Physician’s Desk Reference for herbal
medicines, and British Herbal Compendium (WHO 2000). The monograph for a
certain plant may differ throughout publications, which can create an unnecessary
disagreement in the regulatory approval. Further, research units and manufacturing
companies involved in herbal formulation development faced various challenges in
S. R. Pawar et al.