Background: Traditional Siddha medicine has utilized antispasmodic herbs for centuries in Sri Lanka yet lacks

comprehensive scientific validation. This gap between clinical efficacy and evidence-based documentation

impedes acceptance within modern healthcare systems.

Objective: This systematic review synthesizes ethnobotanical evidence from classical Siddha texts with

contemporary pharmacological research to establish the scientific basis for ten commonly prescribed

antispasmodic herbs.

Methods: A cross-disciplinary approach integrated traditional Siddha Materia Medica classifications with peer-

Trachyspermum ammi, Justicia adhatoda, and Datura species exhibited high-quality experimental evidence with

activity comparable to standard pharmaceuticals. Others demonstrated moderate pharmacological support or

traditional ethnobotanical validation. Critical safety contraindications identified include narrow therapeutic

windows for tropane alkaloid-containing species, cardiovascular risks with Cannabis sativa, and haemostatic

interactions requiring perioperative management.

Conclusion: Substantial alignment exists between traditional Siddha practice and modern experimental

validation. This evidence supports integration of standardized antispasmodic herbal extracts into evidence-based

healthcare, with priority given to clinical safety profiles, quality standardization, and investigation of synergistic

multi-herb formulations characteristic of Siddha pharmacology.

Keywords: Antispasmodic; Siddha; Justicia adhatoda; Trachyspermum ammi; Datura species; Calcium channel

indigenous practitioners, continue to keep herbal therapeutics alive with clinically relevant applications

throughout Sri Lankan communities. This continued use reflects both cultural significance and empirical

validation accumulated over generations of practice.

Despite centuries of documented clinical success, Eastern medical systems face significant barriers to wider

acceptance and integration into modern healthcare frameworks. A critical challenge is the lack of rigorous

scientific evidence supporting traditional claims. Moreover, even when scientific evidence exists, inadequate

dissemination and accessibility of this evidence among practitioners, scholars, and Western medical

professionals has perpetuated a knowledge gap. This disconnect between traditional efficacy and scientific

validation represents a substantial obstacle to the advancement and credibility of Eastern medical practices.

practitioners, and patients seeking informed therapeutic options.

This review focuses on antispasmodic herbs described in Siddha texts and actively used by traditional

practitioners in Sri Lanka. The investigation synthesizes evidence from traditional Siddha classifications with

peer-reviewed pharmacological studies to establish the scientific basis for these herbal remedies. By examining

ten commonly used antispasmodic herbs, this review aims to illuminate the therapeutic potential of traditional

Siddha medicine and provide evidence-based information to community members, healthcare professionals, and

future practitioners. The ultimate goal is to present a clear, scientifically grounded picture of what herbal

medicine is capable of achieving in clinical practice.

mechanistic insights into these traditional claims. Priority was given to experimental models specifically ex-vivo

tissue assays and in-vivo animal studies that utilized extraction protocols congruent with traditional preparation

methods, such as aqueous infusions or ethanolic macerations. This approach ensured a rigorous comparison

between the qualitative therapeutic definitions in the Materia Medica and quantitative pharmacological indices,

including calculated ED50 values and identified receptor-blockade mechanisms. By synthesizing ethnobotanical

wisdom with rigorous literature selection, this methodology identifies the specific phytochemical agents

responsible for the traditionally observed antispasmodic and styptic effects.

Spasticity is defined as a velocity-dependent increase in muscle tone and is a consequence of upper motor neuron

spinal cord or higher centres after injury to motor pathways

. In cerebral palsy, spasticity is characterized by

rate-dependent hypertonia, with muscle tone increasing as the speed of stretch increases

. Antispasmodic drugs

system. It works by stimulating GABA-B receptors, which calms overactive nerve signalling through several

mechanisms. Unfortunately, baclofen has several limitations: it does not easily enter the brain, can cause

excessive drowsiness and muscle weakness, may harm the liver, and its effectiveness can decrease over time. As

a centrally acting alpha-2 adrenergic agonist, tizanidine suppresses muscle tone by inhibiting the spinal release

of the excitatory neurotransmitters glutamate and aspartate. Benzodiazepines mediate their effects via GABA-A

receptors, resulting in postsynaptic inhibition of central nervous system activity. Additional therapeutic options

include gabapentin and the alpha-2 agonist clonidine; however, clonidine's utility is limited by side effects such

as bradycardia and hypotension. Common adverse effects across this drug class encompass sedation, muscle

weakness, dry mouth, urinary retention, and constipation.

Medicinal plants play an important role both in preventive and curative treatments, despite advances in modern

western medicine. A single plant usually possesses multiple medicinal applications. Several scientific studies, in

parallel to this, have also shown the presence of synergistic and/or side effect neutralizing combinations in plants

.

convulsions or spasmodic pains

.

Common anti-spasmodic herbs mentioned in Siddha texts and being used by practitioners in Sri Lanka, after

ileum models

. This pharmacological action supports its traditional medicinal use for treating respiratory

complaints and spasmodic disorders

.

Ruta angustifolia

Ruta angustifolia is explicitly identified as an agent for allaying convulsions and spasmodic pains, frequently

employed in the management of infantile convulsions. The therapeutic utility is noted for its ability to relieve

severe internal spasms.

Hyoscyamus niger demonstrates concentration-dependent relaxation of spontaneous contractions in rabbit

jejunum and guinea-pig trachea

. These relaxant effects are mediated through a dual blockade of muscarinic

receptors and calcium channels.

The aqueous-methanolic extract of Trachyspermum ammi seeds produces dose-dependent inhibitory effects on

intestinal and tracheal contractions.

• Cardiovascular Risks: Cannabinoids are capable of inducing blood pressure fluctuations in a specific triphasic

pattern (low-high-low) and have been linked to increased heart rate, arterial spasms, and postural hypotension.

• Pregnancy: Exposure to Datura during pregnancy has been associated with permanent fetal damage; therefore,

its use is contraindicated for expectant mothers.

Both agents significantly influence haemostasis and require careful management around surgical procedures.

• Haemostatic and Surgical Cautions: Ferula asafoetida and clove oil (Syzygium aromaticum) can slow blood

clotting. Use must be discontinued at least two weeks prior to scheduled surgery to avoid excessive bleeding.

• Drug Interactions: Ferula asafoetida is known to interact with anticoagulants, antiplatelet drugs, and

antihypertensive medications.

Papaver somniferum (Opium): Sudden discontinuation of high-dose opium therapy can trigger a relapse of

delirium and extraordinary depression. Its status as a potent narcotic necessitates strict dosage control to avoid

fatal outcomes.

Trachyspermum ammi (Omam): Human data indicate that its use can reduce both milk and semen production. It

is traditionally advised that "hot-tempered" individuals use the seeds only in small quantities and in combination

with cooling herbs to mitigate physiological irritation.

Moringa oleifera: While the leaves show low toxicity, general considerations for skeletal muscle relaxants apply,

including potential for CNS depression and sedation. Use should be monitored closely in elderly populations,

Justicia adhatoda: Although preclinical findings are promising, a lack of standardized cultivation and extraction

Several species are supported by robust, controlled experimental data, often involving both ex-vivo tissue models

and in-vivo animal studies.

• Trachyspermum ammi (Omam): This species possesses the highest level of multi-modal evidence.

Pharmacological studies demonstrate dose-dependent in-vivo hypotensive effects in rats and ex-vivo inhibitory

actions on rabbit aorta and jejunum. The calcium channel blocking (CCB) mechanism is confirmed through

rightward shifts in Ca 2+ dose–response curves, comparable to the reference standard verapamil. Furthermore,

clinical evidence includes a double-blind randomised controlled trial (RCT) for its topical efficacy in neuropathic

pain.

• Datura species: The evidence for Datura metel, D. stramonium, and D. innoxia is substantial. In-vivo

gastrointestinal motility tests using charcoal meals and castor oil-induced diarrhea models in rodents confirm

for its traditional role as a respiratory and general antispasmodic.

These herbs are supported by clear experimental results, though they often lack the extensive clinical or multi-

modal mechanistic depth of the previous group.

• Ferula asafoetida: Evidence is grounded in ex-vivo studies where gum-resin extracts produced concentration-

dependent relaxation of isolated guinea pig ileum and tracheal smooth muscle. The mechanism is identified as a

dual blockade of muscarinic and histamine (H1) receptors.

• Syzygium aromaticum (Clove): Strong evidence exists for its antispasmodic and antidiarrheal actions through

ex-vivo inhibition of rhythmic contractions in isolated rabbit intestines. In-vivo mouse models using charcoal

transit and castor oil induction further validate its ability to decrease intestinal motility.

• Hyoscyamus niger: Its classification as a potent sedative and antispasmodic is supported by concentration-

dependent relaxation of rabbit jejunum contractions. The evidence points to a dual blockade of muscarinic

For certain substances, the quality of evidence is heavily weighted toward traditional Materia Medica or

established clinical status as a narcotic rather than new experimental assays. Its mechanism is attributed to

benzylisoquinoline alkaloids like papaverine.

• Sphaeranthus indicus (Sivakaranthai): The evidence is largely ethnobotanical, identifying it as a treatment for

epileptic convulsions and spasmodic gastropathies. While modern screening has identified antimicrobial and

immunomodulatory properties, specific quantitative antispasmodic assays are less prominent in the provided

• Ruta angustifolia (Aruvadha): Though explicitly identified for allaying convulsions in infants, it has received

"limited research attention" regarding its chemical composition and biological activity compared to other Ruta

species. Current evidence is primarily traditional.

• Cannabis sativa: Historically valued for relieving severe internal spasms, the source evidence is primarily

traditional. Recent findings provided focus on isolated cannabidiol (CBD) and its effects on multiple ion

such as Trachyspermum ammi and Justicia adhatoda exhibit quantifiable antispasmodic activity that is

comparable to standard pharmaceutical references, while the styptic properties of Papaver somniferum remain

foundational for the management of haemorrhagic disorders. This duality of evidence centuries of successful

clinical application corroborated by modern experimental data underscores the reliability of the Siddha

pharmacopeia.

The implications for the future of Siddha medicine are significant, suggesting a transition from traditional

practice to a more integrated, evidence-based medical system. The identification of specific active compounds,

such as the quinazoline alkaloids in Adhatoda or the tropane alkaloids in Datura, provides a platform for the

standardisation of Siddha drugs. This scientific grounding facilitates the broader acceptance of traditional

therapies within global healthcare frameworks, provided that the inherent complexities of whole-plant extracts

procedures. Accuracy in dosage and a thorough understanding of a patient’s concurrent pharmaceutical regimen

are essential to ensure safety.

Future research must move beyond preliminary screening to address the current gaps in clinical data. Priority

should be given to longitudinal human trials that establish definitive safety profiles and pharmacokinetic

"Vata"-regulating herbs will further illuminate the physiological basis of Siddha’s holistic approach to spasmodic

and inflammatory conditions.

The authors wish to acknowledge the six Siddha physicians, four Ayurveda physicians, three Unani physicians,

and seven traditional medical practitioners in Sri Lanka whose clinical knowledge informed the selection of

herbs reviewed in this study. The authors also acknowledge the Faculty of Siddha Medicine, Trincomalee

Campus, Eastern University of Sri Lanka, for institutional support. This research received no specific grant from

any funding agency in the public, commercial, or not-for-profit sectors.

Authors have declared that no competing interests exist.

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