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Pharmaceutics) and chikitsa (therapeutics). Here, preformulation exhibits a significant role in
improving logical, safe, and effective herbal medicines (Fig. 9.1).
From historical literature, we can learn a lot about the qualities of single medications and
multiingredient formulations. This knowledge can be put to good use by the industry during
preformulation R&D. Solubility, dispersibility, hygroscopic nature, bulk formati on, compo-
nent interaction, and binding qualities must all be investigated.
2.1.1 Quality control of medicinal plants
Phytopharmaceuticals’ safety and efficacy are directly influenced by medicinal plants ’
quality control employed in the herbal product. For quality assurance, good agricultural
and collection practices (GACP) for medicinal plants are one of the first steps, which is
unswervingly dependent on the efficacy and safety of herbal drug products, and will also
lead to the protection of natural herbal resources for long-term use. Chemical analysis is
currently the most effective tool for standardization, identification of contamination, and me-
dicinal plant recognition and authentication. As a complement to other methodologies, tech-
niques based on molecular biology can be used to authenticate medicinal plants. Following
are some of the critical quality control parameters.
• Microscopic and macroscopic examination: assists false identification of desired variety
and detection of contaminants.
• Chromatog raphic analysis: helps in the recognition of crude drugs based on crucial
chemical markers.
FIGURE 9.1 Need of preformulation studies.
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• Extractive values: these are indicative weights of the extractable chemical constituents of
the crude drug under different solvents’ environments.
• Moisture content: it is checked to assist avoid inaccuracies in estimating the actual
weight of medicinal material. Low moisture indicates that the herbal product will be
more resistant to deterioration.
• Quantitative chemical evaluation: to assess the amount of the major classes of
phytoconstituents.
• Qualitative chemical evalu ation: this assis ts in the identification and characterization of
crude drugs in terms of phytochemical constituents. To discover and isolate the active
ingredients, it uses a variety of analytical techniques.
• Foreign organic matter implies removing matter other than the source plant to get the
plant drug pure form.
• Ash values: vital criterion to analyze the purity and identity of crude drug-total ash,
acid insoluble ash, water-soluble ash, sulfated ash, etc.
• Toxicological studies: pesticide residues, potentially hazardous ingredients, safety tests
in animals such as LD50, and microbial assays to identify the absence or presence of
potentially harmful microorganisms are all aided by this. As mentioned in the next sec-
tion, the procedures entail various scientific examinations, including physical, chemical,
and biological evaluations using a variety of analytical methods and equipment. The
same goals of such research into herbal quality assurance are as diverse as the proced-
ures used. Section 2.2 contains more information.
2.1.2 Issues in ensuring the quality control of herbal drugs
The identity of the plant material is the essential component. The process of botanical qual-
ity control begins with the identification of the plant. According to WHO general recommen-
dations for methodology on research and assessment of traditional medicines, the first stage
in assuring the quality, safety, and efficacy of traditional medicines is correct identifi cation.
The common English name, the transliterated name, the Latinized medicinal name, and
the scientific name are the four options for nami ng a plant. Misidentification can occur
when binomial names are not used. Nonuniformity of plant material owing to collecting
from undomesticated sources and diverse geographical places causes misunderstanding in
procuring authentic plant resources. Collections are always done by uninformed and un-
taught persons who are unaware of the herbal drugs’ identities. Traders and suppliers typi-
cally have a limited understanding of medicinal plants and the collection of wildly growing
species from woods and wastelands, leading to inferior quality [3].
Another serious issue is the adulteration of botanical preparations. Several medicinal herbs
are on the verge of extinction due to forest fragment ation, overexploitation of some plants,
and habitat loss. These and other factors (such as the cost of raw materials) make it difficult
to obtain genuine drugs, which encourages plant adulteration through the use of substandard
commercial vari eties, synthetic additives, worn-out drugs, or less expensive plants, or the uti-
lization of another vege tative part [4]. Several investigations claim that various herbal prod-
ucts contain adulterants and heavy metals that are not mentioned [5]. It is possible to utilize a
medicinal adulterant on purpose.
Furthermore, many natural products’ drug-drug interactions, pharmacokinetics, pharma-
codynamics, precise mechanism of action are still in their infancy. Simultaneously, an
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increasing number of reports of fatal or harmful effects of herbal products highlight the
importance of international registration and regulation of herbal medications and the creation
of safety checks. Clinicians should not administer or advocate herbal therapies that have not
been proven efficacious in a rigorous trial as if they were pharmaceuticals. On the other hand,
patients continue to be drawn to such herbal products, and this truth cannot be overlooked.
As a result, it is critical to inquire about patients. This also highlights the critical requirement
for botanical quality control.
Variations in botanicals are another element to consider. The safe and effective delivery of
natural products necessitates uniformity in biological activities and composition. On the
other hand, Herbal preparations rarely meet this standard due to rough growing conditions,
genetic inconsistency, difficulty in identifying plants, variations in harvesti ng procedures and
extract proce ssing, and, most importantly, a knowledge deficiency about bioactive principles.
Environmental factors such as temperature, sunlight, altitude, rainfall, soil, storage condi-
tions, various harvesting time, procedures, and manufacturing processes such as extraction,
drying, purification, and selection, can all affect product quality and plant chemical concen-
trations. Environmental factors such as insect feeding and microbial diseases can influence
secondary metabolites and, as a result, the plant’s chemical makeup. Chemical ingredient
concentrations are also varied in different portions of the same plant (e.g., roots, stems,
and leaves). Diurnal variations, for instance, paclitaxel, opium alkaloids, and seasonal shifts,
can contribute to herbal medication variability. The medicinal and poisonous components of
the plant differ depending on the portion of the plant used and the stage of maturity at which
it is harvested. Different producers’ products differ significantly, and it is impossible to con-
trol all factors that influence plant chemical composition [6].
Due to time and environmental circumstances, medicinal plant properties may have
changed. All of these conditions harm the quality of enriched fractions and, as a result, phy-
topharmaceuticals made with them [7]. The requirement for standardization and quality con-
trol of herbal products was express ed by Patwardhan et al. as follows [8].
• The identity of plant material may have altered over the last thousand years due to the
dynamic process of evolution.
• When traditional remedies were produced, technology and the concept of standardiza-
tion were considerably different.
• The provision of authentic raw material has become a challenge as a result of
commercialization.
2.1.3 Good agricultural and collection practices (GACP) guidelines
The World Health Organization (WHO) has produced technical standards for the quality
control of herbal medicines, the most recent of which are the guidelines on Good Agricul-
tural and Collection Practices (GACP) for medicinal plants. The instructions outline the
techniques and precautions necessary for the proper cultivation and gathering of medicinal
plants and the recording and documenting of vital data and information during their pro-
cessing. While herbal pharmaceuticals and other companies strive to meet quality control
criteria for herbal medicines, producers, handlers, processors, and farmers cannot be forced
to adopt proper agricultural and collection methods for medicinal plants. Training farmers
and other relevant people is one of the many vital steps that must be taken to ensure that
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excellent agricultural and collection techniques are followed in order to get high-quality me-
dicinal plant materials.
The main goals of GACP guidelines are to offer the quality assurance of medicinal plant
materials used as the source for herbal medicines, intending to improve the efficacy, safety,
and quality of finished herbal products; direct the formulation of regional and national GACP
monographs and GACP guidelines for medicinal plants, as well as related standard operating
procedures; and enlist the help of others in developing these guidelines. Other international
criteria, inc luding Good Manufacturing Practices (GMP), Good Sourcing Practice (GSP),
Good Clinical Trial Practice (GCTP), Good Agricultural Practice (GAP), and Good Laboratory
Practice (GLP), have been developed to ensure the quality of herbal medicines.
2.1.4 WHO guidelines for the standardization of raw herbal drug materials
The standardization of raw herbal drug materials includes the following parameters.
1. Authentication
2. Foreign matter (herbs collected should be free from soil, insect parts, animal excreta,
etc.)
3. Organoleptic evaluation (sensory charactersdtaste, appearance, odor, feel of the drug,
etc.)
4. Tissues of diagnostic importance present in the drug powder
5. Ash values and extractive values
6. Volatile matter
7. Moisture content determination
8. Chromatographic and spectroscopic evaluation
9. Determination of heavy metalsdcadmium, lead, arsenic, mercury, etc.
10. Pesticide residue
11. Microbial contamination
12. Afflatoxins should be removed entirely or should not be present.
13. Radioactive contamination
2.1.5 Parameters for preformulation study of phytopharmaceuticals
• Solubility and dispensability: The natural products’ solubi lity is an important physico-
chemical feature because it impacts the drug’s bioavailability, the rate of herbal drug
release into the dissolution media, and, as a result, the phytopharmaceutical product’s
therapeutic efficacy. Knowing the level of solubility is crucial for determining whether
more steps of adjustment are required to get the desired quantum or whether a filtration
step is required throughout the manufacturing process.
• Hygroscopicity: This could be taken into account in stability investigations of phyto-
pharmaceuticals. Herbal products are highly susceptible to structural alterations caused
by moisture in the air. They might be hygroscopic or effervescent. It could have signifi-
cant consequences during the production process, environmental controls, packaging,
and, most critically, phytopharmaceuticals’ stability and microbiologi cal characteristics.
During tablet manufacturing, direct compression of the active substances with sufficient ex-
cipients is one of the most advantageous processes; provided that drugs and excipient demon-
strate low hygroscopicity, good flow property, and compactibility [9]. Plant extracts are
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generally hygroscopic, viscous, and amorphous material and possess poor physicomechanical
property and flow ability. The aforementioned problems can be avoided by incorporating
nonhygroscopic excipient (e.g., dextran) into the extracts prior to direct compression [10].
• Organoleptic properties: Color, scent, taste, and touch are examples of physical proper-
ties that may be investigated solely throu gh sense organs. Color represents the external
color of a crude drug (e.g., black pepper is black colored). Every material’s color is
strongly related to its composition; most extracts are dark brown or black. Similarly,
chemical nature is linked to flavor and touch. The odor of herbal drugs may be sweet
aromatic (fennel), aromatic (coriander fruit), fragrant (cinnamon), aromatic spicy (long
pepper), etc. Some medicinal plants emit a distinct odor. Sulfur- containing herbal prod-
ucts may emit an unpleasant sulfur odor when burned. The taste may be spicy (cori-
ander), sweet (licorice), bitter (kalmegh), aromatic (cumin), agreeable and pungent
(ginger), pungent (capsicum), slightly pungent (tulsi), acrid (cannabis), etc. Fractured
surfaces are the essential characteristics of cinchona, cascara, quillia bark, and quassia
wood.
• Compatibil ity
No two elements with incompatibility to each other must be formulated together.
Interaction with excipients: Although excipients are inert and do not interfere with the herbal
drug’s interaction with the body, this is not always the case. For example, herbal products
produced with magnes ium oxide/magnesium carbonate as an anti-caking agent may have
a little “laxative effect” or intensify such an effect if the phytopharmaceuticals are also known
to have a laxative effect.
Herbal drug-herbal drug interaction: Combinations of various plant materials should also be
sought out and investigated for therapeutic effects. The phytoconstituents present in the phy-
topharmaceuticals may interact favorably or unfavorably with other herbal drugs in a poly-
herbal product. The components may be synergistic and boost each other’s effects. They may
be adverse to one another and neutralize each other’s effect. Ephedra (Ma huang) is a popular
herbal drug incorporated into a variety of formulations for weight loss, “energy” enhance-
ment, and symptomatic treatment of asthma. A pharmacodynamic interaction leading to a
fatality has been reported with simultaneous administration of caffeine and ephedra [11],
probably as a result of additive adrenergic agonist effect of the ephedrine alkaloids and
caffeine on the cardiovascular system and the CNS [12].
Herb-drug interaction: Concurrent administration of an aqueous extract of fruit of Foenicu-
lum vulgare, in rats was shown to reduce maximum plasma drug blood concentration, and
urinary recovery of ciprofloxacin. The most probable mechanism for such interaction is che-
lation of ciprofloxacin by metal cations present in the extract owing to poor absorption.
• Particle size and shape: Smaller the size of the particles, the better the surface area. The
easier it is for particles to disperse, dissolve, and assimilate in the body, the smaller they
are.
• Stability: Before any new phytopharmaceuticals are put into clinical trials, their stability
profile is required before moving further with product development. Environmental var-
iables may cause changes in the substance. It may decay, reduce its potency, or change
to another chemical due to a reaction, rendering it dangerous to use. As a result,
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stability testing is the most used method for determining shelf life and storage condi-
tions for phytopharmaceuticals. Stability studies are linked to establishing and guaran-
teeing the herbal product’s safety, quality, and efficacy from the early stages of
development through the end of its life cycle.
• Binding properties: The information on binding qualities can help to decide which ex-
cipients to employ. It could also refer to the phytopharmaceuticals’ dose form, such as
capsules or tablets.
• Purity: Preformulation studies must also consider this factor. The limit of impurity is
determined for each substance based on its dosage and toxicity. Other investigations
such as stability, degradation, and toxicity cannot be conducted unless the herbal drug’s
purity is verified. Pesticide residue, TLC, HPLC, UV absorption, and IR spectra are only
a few of the characteristics used to determine the purity of an herbal drug. All
poisonous botanicals, highly potent medications, and all metals and minerals should be
used only after thorough purification.
Once the individual extract has been characterized and its similarity with the history of
safe use material has been established, preformulation studies can be undertaken. There is
not much guidance and techniques for herbal medicines for their preformulation studies
compared to those of synthetic drugs, where much guidance and techniques are available.
Several aspects and measurement techniques are needed to study the properties of the phy-
topharmaceuticals to know the ability to obtain qualit y solid dosage form formulations.
Different editions of Ayurvedic Pharmacopeia of India should be referred for other tests/
protocols.
Preformulation studies can be carried out once the individual herbal extract has been
defined and its similarity to the history of safe use material has been determined. Herbal
medicine lacks the same level of supervision and approaches that are accessible in other
fields. To know the ability to generate quality solid dosage form formulations, specific ele-
ments and measuring procedures are required for studying the properties of
phytopharmaceuticals.
2.2 Toxicity issues
Toxicological issues related to the use of herbal medications are complex, but they have
been linked to a slew of significant side effects, ranging from cardiovascular issues to psycho-
logical and neurological impacts, liver toxicity or dysfunction, hematologic and renal toxicity.
Toxicity evaluation of phytopharmaceuticals should be conducted under international guide-
lines issued by relevant authorities such as the World Health Organization (WHO), OECD,
International Conference on Harmonization (ICH), or European Union (EU) authorities.
However, a minimal toxicity test battery similar to that used for pharmaceutical goods
should be established for toxicity evaluation of plants not used in the traditional practice or
with unclear safety. Toxicokinetics, genotoxicity, reproductive and developmental toxicity,
repeated-dose toxicity, single-dose toxicity, local tolerance carcinogenicity, and other toxicity
studies, such as immunotoxicity, antigenicity, and impurities, are a few examples. A reduced
battery of tests, including developmental and reproductive toxicity, carcinogenicity, and gen-
otoxicity, defined by competent institutions, is required for plants used in traditional medicine.
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Herbal toxicity is usually diagnosed after considering the temporal link between phyto-
pharmaceuticals exposure and the onset of the adverse event, as well as ruling out other
possible causes. However, in several situations, causality analysis employing adequate meth-
odologies for dete rmining phytopharmaceutical toxicity has failed to establish any causal ef-
fects or has indicated a weak causal association. The report of toxic liver injury caused by the
herb Chelidonium majus L. ingestion in patients from various European countries, for example,
has given cause for alarm [13].
Furthermore, even though weak or no causality of herbal toxicity has been demonstrated
in many cases, some researchers have reported on the potentially harmful nature of herbal
medications. Blue cohosh possesses direct cardiotoxic and sympathomimetic effects, which
induce coronary vasoconstriction and decreased oxygen flow to the heart, resulting in
morbidity and mortality in the fetus or newborn infant [14]. Similarly, cardiac glycosides
have been associated with hyperkalemia, a side effect seen in a patient who was using a va-
riety of herbal medicines [13].
2.2.1 Toxicological data assessment
General considerations: In today’s scientific rationale, even herbal treatments with a long
history of traditional use should be backed up by scientific proof. In general, the history of
plant material’s traditional use should be instructive in planning experimental toxicity inves-
tigations. Phytopharmaceuticals should also be tested for some specific harmful effects, such
as developmental and reproductive toxicity, genotoxicity, and carcinogenicity, because these
effects may not appear during traditional use. Additional preclinical testing will be required
if insufficient data on traditional herbal remedies or if these products have a suspect status
[13,15]. On the other hand, the EMEA indicated that well-documented clinical evidence,
epidemiological studies, and statistics, as well as post-marketing experiences for herbal prod-
ucts, may be evaluated to prevent unnecessary use of experimental animals. This assessment
may not be used to traditional herbal materials if the existing data or historical use data are
insufficient or if preclinical investigations are needed to address a safety issue identified or
suspected.
Selection of test models: It is critical to use suitable animal models or other alternative test
systems to obtain scientifically reliable information. Ex vivo and in vitro preparations and an-
imal models can be employed as test platforms. In the related sections, animal species to be
employed in test systems are discussed. Subcellular organelles, isolated organs and tissues,
receptors, cell cultures, cellular fragments, transporters, enzymes, and ion channels are exam-
ples of ex vivo and in vitro alternative test systems. Toxicity in an entire animal may no t al-
ways be observed in cell culture. As a result, in vivo tests on laboratory animals may be more
beneficial for toxicity identification and characterization than in vitro investigations. Because
most phytoconstituents undergo metabolic processing in the body after being taken orally,
in vitro test settings are unlikely to reveal the genuine toxicity profile of oral herbal drugs
[16].
Sample size: It is stated in several official guidelines issued by the Organization for Eco-
nomic Co-operation and Development (OECD), the Food and Drug Administration (FDA),
and European authorities. The experimental design should contain appropriate negative
and positive control groups. Suitable positive and negative control substances are mentioned
in the subsections of this document as official test guidelines [13].
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Route of administration: In a toxicological survey, ethnomedical knowledge on the tradi-
tional usage of the plant treatment will help decide which administration route to adopt. The
majority of herbal medicines are taken orally. As a result, after administering the test material
to test animals by oral gavage or food supplementation, it is critical to examine gastrointes-
tinal toxicity and identify afflicted tissues or organs. On the other hand, intraperitoneal injec-
tions are occasionally employed to evaluate the hazardous potential of test compounds.
However, this method of administration would not reflect the actual dangers, which might
be owing to an absence of gastrointestinal metabolites of the plant ingredients. Owing to
these justifications, the selection of administration routes is critical to evaluate the safety of
any phytopharmaceuticals. With these considerations, the choice of delivery method is
crucial when assessing the safety of phytopharmaceuticals [13].
Dose levels or concentrations of phytopharmaceuticals: Experiments in vivo should be
intended to describe the dose-response relationship, while in vitro experiments are intended
to set up a concentration-activity correlation. The toxic doses need to be evaluated in associ-
ation with the primary biological effect in test animals or the proposed therapeutic effect in
humans.
Testing strategy: Phytopharmaceuticals’ therapeutic benefits are frequently manifested af-
ter lengthy periods of repeated dosage, which can raise the risk of toxicity. For example, in-
dications of liver toxicity may appear after the organ has been significantly weakened, which
could occur after several weeks of utilizing a phytopharmaceutical. Although humans can
typically recognize and forecast acute or subacute toxicity indicators, there have been no pre-
dictable symptoms (developing delayed harmful consequences) associated with long-term
usage of the herbal treatment. As a result, in addition to acute and subacute toxicity testing,
subchronic and chronic toxicity tests are more helpful in assessing the safety of phytopharma-
ceuticals. On the other hand, phytopharmaceuticals may affect the pharmacod ynamics and
pharmacokinetics of the pharmacotherapy, resulting in a loss in effectiveness or an increase
in side effects. As a result, it is also a good idea to look into possible interactions between
phytopharmaceuticals and medications with a restricted therapeutic index, such as digoxin,
warfarin, antiepileptics, and others. Furthermore, research on cytotoxicity, genotoxicity,
mutagenicity, carcinogenicity, and reproductive and developmental toxicity should be con-
ducted to support the safe and sound use of phytopharmaceuticals, especially if genotoxicity
is suspected [16].
Contaminants in phytopharmaceuticals: Agricultural residues (i.e., pesticides, fertilizers),
heavy metals, microbes (endotoxins, exotoxins, mycotoxins), and industrial litter, which are
not natural components of plants, can contaminate phytopharmaceuticals. These contami-
nants may interfere with the results of toxicological testing on phytopharmaceuticals due
to their possible harmful effects. As a result, before submitting phytopharmaceuticals to
toxicity testing, they should be checked for such contaminants. Heavy metal contamination
has become a growing concern for herbal products due to increasing environmental dangers.
Heavy metals such as cadmium and lead are responsible for causing nephrotoxicity and gen-
otoxicity; hence contamination of phytopharmaceuticals with these hazardous metals might
skew the results. As a result, potential contaminants that could skew the results, such as pots
used for remedy production or plant material collection sites, should be carefully considered.
Heavy metal pollutants such as arsenic (As), lead (Pb), cadmium (Cd) can make herbal prod-
ucts poisonous. As, Cd, and Pb have WHO maximum acceptable limits of 1.0, 0.3, and
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10 ppm, respectively [17]. Agricultural practices and industry emissions accounted for indi-
rect causes. Pesticides may contaminate plant material, and poor manufacturing procedures
may contaminate bacteria, fungi, and other microbes. Contamination of plant materials with
agricultural agents, notable pesticides, is also regarded as a severe threat. Contaminations of
this nature are more common in cultivated plants, but wild species taken near cultivation
zones may still be in danger. Contamination of raw and processed plant materi als with my-
cotoxins is another external risk factor. Due to faulty processing or storage conditions, this is
especially common for plant materials obtained from herbalists or spice shops. Contamina-
tion with mycotoxin could skew the results of phytopharmaceutical carcinogenicity and hep-
atotoxicity studies [13].
2.2.2 Toxicity test battery
Single-dose toxicity (acute toxicity): This needs to be performed according to the appli-
cable international criteria that have been published or accepted. The toxicological examina-
tion of phytopharmaceuticals begins with an investigation of acute toxicity. This is defined as
“the toxicity induced by a medicine when it is provided in one or more doses over a period
not exceeding 24 h” in official papers, such as the ICH Guidance. The fixed-dose method fore-
goes lethality as an endpoint and is not intended to result in death [18]. The animals’ pain is
computed, making this a constructive modification for an alternative method. The acute toxic
class technique is used to identify a range of exposure levels at which mortality is likely to
occur, rather than a specific LD50 number. A sophisticated progressive dosing technique is
used in the test. The considerable reduction in the number of experimental animals is a
benefit of this strategy [19]. The going up and down method enables the calculation of the
LD50 value and confidence intervals, as well as the detection of toxicity symptoms [20].
The number of experimental animals employed in this study has been drastically reduced.
Both for the herbal extracts and the isolated compounds, the beginning dose for the fi xed-
dose levels can be 5, 50, 300, and 2000 mg/kg, as a dose expected to generate apparent
toxicity, if achievable, based on evidence from in vivo and in vitro data. If no other informa-
tion is available, the initial dose will be 300 mg/kg. Acute toxicity studies are used to estab-
lish a dose that is damaging but not lethal, which will be used in dose selection tests in the
future. The test sample is fed to experimental animals at increasing doses to determine the
dose that produces life-threatening central toxicity. It is also a good idea to consider employ-
ing vehicle control groups. The most prevalent test animals are rodents, with rats being the
most popular. Acute toxicity testing is also used to estimate the LD50 dose (the dose which
causes the death of half of the test animals). Many dose levels should be considered to
compute the approximate lethal dose [18e20].
Acute toxicity testing can provide preliminary information on the toxicity of phytophar-
maceuticals. Data from acute toxicity studies are likely to be utilized to offer evidence of
the possible dangers of an acute overdose in humans. In the absence of other data, single
oral dosage studies are also utilized to establish the extent of the toxicity and may aid in
determining the likely target organs of toxicity [21].
Repeated-dose toxicity: The primary goal of repeated-dose toxicity testing is to determine
the in vivo consequences of daily phytopharmaceutical exposure for periods of 28 days or
more. These test systems inv olve rodent species; however, rats are recommended. Such
research should disclose any potential toxicity targets, which could include organs, tissues,
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or cells. Repeated administration of the test samples causes any physiological and anatomo-
pathological alterations, which are determined. The test should also allow for the establish-
ment of dose-response relationships for any toxicity targets, allowing for the determination
of the nature and degree of toxic effects [22].
Subacute toxicity: These studies give information on the potential dangers of repeated oral
exposure and may be relevant in determining the dosing regime for longer-term adm inistra-
tions depending on the findings of additional studies conducted under OECD and ICH stan-
dards. For 28 days, experimental animals (rats and mice) are given the test sample orally at
progressive doses. This test also determines the test sample’s No-Observed Adverse Effect
Level (NOAEL) and offers information on the dose-response relationship [22].
Any available toxicity and (toxico-) kinetic data should be used to determine dose levels.
The most incredible dose level that causes harmful indications without death or severe
suffering should be chosen first, followed by a lowering dose sequence, preferably at two
to fourfold intervals. A fourth test group with substantial intervals (e.g., more than a factor
of 10) between dosages is frequently advised. Throughout the administration period, the test
animals are monitored daily for any signs of morbidity or mortality. Detailed clinical obser-
vations should be made for all animals before the first exposure (to enable within-subject
comparisons) and at least once a week after that. Surviving animals are also euthanized
and necropsi ed at the end of the test. At least once a week, take note of changes in body
weight and food/water consumption. At the end of the test period, all test animals undergo
clinical biochemistry tests, gross necropsy, hematological analysis, and specific histopatholo-
gy of organs. Additional tissue analyses may be required based on the results obtained [22].
Subchronic toxicity: For 90 days, the test sample is orally administered in progressive
doses to the groups of experimental animals. The subacute toxicity studies follow a similar
strategy for dosage level selection and observation and evaluation patterns in the experi-
mental animals. Ophthalmoscopy, electrocardiograms, and other particular toxicological
studies can be conducted if necessary. Subchronic toxicity experiments impart substantiation
for determining safety criteria for human exposure based on empirical findings, such as main
toxic effects, impacted organs, and determination of NOAEL value, as well as dose levels for
chronic research [23].
Chronic toxicity: The test drug is given to the experimental animal groups in gradua ted
amounts every day in chronic toxicity studies, as stated earlier in repeated-dose toxicity ex-
periments. In chronic toxicity testing, rodents are recommended; however, nonrodent species
may be necessary under specific regulatory regimes. The oral route is the most common route
of administration, but inhalation or cutaneous routes may also be utilized depending on the
application method in traditional use. One or more interim kills, such as at 3 and 6 months,
may be included in the study design. Throughout the administration period, the animals are
continuously monitored for any signs of illness or mortality [24].
Brine shrimp (Artemia salina) lethality assay: Although It is employed as a rapid and
straightforward acute toxicity test system for assessing the potential toxicity of some herbal
medicines, it is not included in any worldwide health institution’s toxicity testing protocols
due to its dubious utility. Lower sensitivity, Artemia strain standardization, characterization
issues, and the organism’s resistance to numerous phytochemicals such as phenolic com-
pounds and minerals are significant negatives [25].
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