INTRODUCTION:

The drugs used in the so called ‘alternative and complementary system’ of medicine are also known as herbal drugs^1,2. In the early twentieth century herbal medicine was prime healthcare system as antibiotics or analgesics were not available³. Ayurveda is the most ancient healthcare system and is practiced in India, Srilanka and other countries^4,5. Atharveda (around 1200 B.C), Charak Sanhita and Shushrut Sanhita (100-500 B.C) are the main classics that given detailed descriptions of over 700 herbs^6,7. These medicines are used by about 60 percent of the world population^8,9. In western world also, the use of herbal medicines is steadily growing with approximately 40 percent of population reporting use of herb to treat medical illness within the past year^10,11. Public, academic and government interest is growing exponentially due to the increased incidence of the adverse drug reactions and the economic burdens of the modern system of medicine¹². There is a need to integrate traditional medicine into the modern medicine practices.

This requires clinical validation by conducting controlled clinical trials¹³. Herbs are supposed to be safe but many unsafe and fatal side effects have recently been reported^12,14,15. There could be direct side effects, allergic reactions, effects from contaminants and/or interactions with drugs and other herbs. Studies should be conducted to examine the side effects considering the interaction with other herbs and modern drugs¹⁶. The risk-benefit ratio of the herbal drugs should be evaluated. Most of the herbal products do not have drug regulatory approval to demonstrate their safety and efficacy¹⁷. Therefore, present paper focus on the procedure and critical issues for conducting clinical trials in our country.

Categories of Herbal Products¹⁸:

The herbal products can belong to any of the three categories given below:

a. A lot is known about the use of a plant or its extract in the ancient Ayurveda, Siddha or Unani literature or the plant may actually be regularly used by physicians of the traditional systems of medicine for a number of years. The substance is being clinically evaluated for same indication for which it is being used or as has been described in the texts.

b. When an extract of a plant or a compound isolated from the plant has to be clinically evaluated for a therapeutic

effect not originally described in the texts of traditional systems or, the method of preparation is different, it has to be treated as a new substance or new chemical entity (NCE) and the same type of acute, subacute and chronic toxicity data will have to be generated as required by the regulatory authority before it is cleared for clinical evaluation.

c. An extract or a compound isolated from a plant which has never been in use before and has not ever been mentioned in ancient literature, should be treated as a new drug, and therefore, should undergo all regulatory requirements before being evaluated clinically.

According to WHO, "Herbal Medicines" should be regarded as, "Finished, labeled medicinal products that contain as active ingredients aerial or underground parts of plants, or other plant material, or combinations thereof, whether in the crude state or as plant preparations. Plant material includes juices, gums, fatty oils, essential oils, and any other substance of this nature. Herbal medicines may contain excipients in addition to the active ingredients. Medicines containing plant material combined with chemically defined active substances, including chemically defined, isolated constituents of plants are not considered to be herbal medicines. Exceptionally, in some countries herbal medicines may also contain, by tradition, natural organic or inorganic active ingredients which are not of plant origin¹⁹.

Past and current status:

India is globally attracting collaborative contract proposals for conducting clinical trials and many have already come forward to set up their clinical research organizations (CRO's). The projected figures for the various aspects of clinical research (market value, revenue, staff requirement) for the next five years, promise a growth at a rate greater than 20 percent (Table 1). Pharmacopoeial standards of 671 medicinal Plants parts have been developed and published in the form of Ayurvedic & Unani Pharmacopoeia of India by AYUSH. Pharmacopoeial work for 100 Ayurvedic compound formulations is about to complete and pharmacopoeial standards of about 50 formulations are expected for publication by May, 2007. 20 laboratories are engaged in the pharmacopoeial work of Ayurveda, Siddha and Unani drugs supported under a central project. National Formularies containing standardized composition of 1696 multi-ingredient classical formulations of Ayurveda, Siddha and Unani systems are also published as official documents for industry to follow²¹.

The DCGI is responsible for regulatory approvals of clinical trials in India and his office depends on external experts and other government agencies for advice²⁰. Various concerned Ministries / Departments

of Government of India are actively involved in R&D in the pharmaceuticals sector including herbal medicines for development of drugs for chronic diseases like blood pressure, diabetes, Asthma etc. As a result, a number of projects have been mounted related to R&D for development of drugs for chronic diseases like blood pressure, diabetes, Asthma etc besides the drugs for life style diseases like cancer, Diabetes, Gastric Ulcer, Dementia etc. As of now 28 new IND molecules developed within the country are undergoing Phase-I Clinical trials. There are also efforts to validate treatment from Traditional Systems of Medicine so that cost effective therapy with minimum or no side effects can be made available to the people. As there are a number of alternate therapies claiming cure for many conditions, guidelines for recognizing any new system of therapy have been developed by the Standing Committee on Alternate System of Medicine under the Chairmanship of DG, ICMR²¹ (Table 2).

ICMR has already initiated a programme for setting up Clinical Trial Registry in India (CTRI) in which all Clinical Trials both in the modern medicine and traditional medicine will be entered so that the data base will be available on all Clinical Trials conducted in India. This programme is funded by the DST and the WHO²¹.

Clinical trial of herbal drugs:

Regulatory approvals in India can usually take 3 months, which is comparable to most Asian and European countries. Although the US FDA gives approval in 30 days, most US trials are delayed because suitable subjects are not available in adequate numbers. The timelines for approval are often unpredictable in India as the Drugs Controller’s office depends on external experts and other government agencies such as the Indian Council of Medical Research (ICMR) and the Department of Biotechnology (DBT) for advice and there are additional permissions required for the import of trial samples and export of blood samples to foreign central laboratories. The potential for fast recruitment can partly offset the delay in the regulatory approval. Nevertheless the regulatory situation is a major concern for all pharmaceutical sponsors and Contract Research Organizations (CROs), who continue to press for improvements in the regulatory approval process to make it predictable, accountable and less cumbersome. The other aspects of regulatory revisions such as adoption of Good Clinical Practices (GCP) guidelines, removal of import duty on clinical trial samples, elimination of restrictions on concurrent trials, anticipated patent law changes have shown India’s seriousness about becoming a hub of global clinical trials²².

Once the animal studies are over, the herbal medicines are studied on human beings with compliance to GCP guidelines²².For the herbal remedies and medicinal plants that are to be clinically evaluated for use in the Allopathic System and which may later be used in allopathic hospitals, the procedures laid down by the office of the DCG (I) for allopathic drugs should be followed. This does not pertain to guidelines issued for clinical evaluation of Ayurveda, Siddha or Unani drugs by experts in those systems of medicine

which may be used later in their own hospitals and clinics. All the general principles of clinical trials described earlier pertain also to herbal remedies. However, when clinical

trials of herbal drugs used in recognized Indian systems of Medicine and Homoeopathy are to be undertaken in Allopathic Hospitals, associations of physicians from the concerned system as co-investigators/ collaborators/ members of the expert group is desirable for designing and evaluating the study²³.

Good clinical practice should be applied to all stages of clinical trials to ensure that quality and ethical requirements for clinical studies are met. It is expected that a traditional practitioner familiar with the product proposed for investigation be an integral member of the protocol development team, where those traditional practitioners exists. For all clinical trials, biostaticians should be consulted to ensure that the sample size is sufficient to satisfy the primary endpoint/objective²².

Typical information required for the preparation of a study protocol²²:

· Aim of the study

· Aim for marketing authorization: country and authorization level

· Therapeutic indication

· Administration route and dosage

· Any available information of pharmacological action and pharmacological action and pharmacokinetics/pharmacodynamics

· The number of compounds

· The preferred starting date

Phytopharmacological research timeline²²:

· Literature research and preparation of research program – 2-6 weeks

· Development of validated assay systems and chemical analysis – 4-8 weeks

· Biological activity – 4-8 weeks

· Extraction method development – 8-12 weeks

· Separation method development – 8-12 weeks

· Isolation of active compound(s) – 4-6 weeks

· Identification of active compound 8- 12 weeks

Report: 2-4 weeks

Total approximately 1 year

Revised Schedule Y (20th January 2005)¹⁸

Appendix I : Data to be submitted with application.

Appendix II : Contents of clinical study reports

Appendix III: Animal toxicology

Appendix IV: Animal pharmacology

Appendix V: Informed consent checklist and form

Appendix VII: Investigator’s undertaking

Appendix VIII: Ethics committee constitution

Appendix X: Contents of clinical study protocol

Appendix XI: SAE reporting data elements

Stages of clinical trial²³:

Phase I studies:

It involves test of new drug of treatment in a small group of people (20-80). It is designed to determined

safety associated with increasing doses in normal volunteers and also investigate toxicity and drug levels in states in which drug level might be altered such as fed vs fasted condition, in renal or hepatic impairment in phase I. For herbal tradional medicines this phase in generally unnecessary because traditional dosage regimens conveys reasonable confidence that these regimens can safely be administered to a small numbers of carefully monitored clinical subjects in phase II trials. Phase I study usually takes several months.

Phase II studies:

It evaluates the efficacy of a range of dosages in individuals with disease (large group of 100-300). It evaluates the maximum tolerated dose determined in phase I normal volunteers studies. If the dose is effective, dose ranging downwards would be investigated. If the phase I dose is ineffective, dose ranging upwards upwards may be performed. Phase II dose-ranging studies utilize a relatively small small number of patients per dosage group. Placebo and standard intervention groups may be included. If surrogate markers rather than disease endpoints are used in the phase II studies, it may be necessary to repeat dose ranging in phase III trials with more valid disease endpoints. It is important to verify tolerance in this phase. Both the literature review and the provisions in the protocol to be performed should focus on complete review of the clinical safety parameters. Phase II studies take longer-from several months to a few years- and can involve up to several hundred patients.

Phase III studies:

This trial is performed after establishing dose-ranging phase II data are available and involves expended trials of safety and efficacy. They are performed after preliminary evidence suggesting efficacy for the intervention has been obtained, and are intended to gather the additional information about efficacy and safety that is needed to evaluate the overall benefit-risk ratio of the intervention and to provide an adequate basis for general clinical use. Phase III studies usually include large numbers (several hundred to several thousand) of subjects, may involve human populations with broaden intervention characteristics than were used in the phase II trials, and involve statistical comparison of the intervention of the intervention to standard and/or placebo interventions.

A phase III study further examines the effectiveness of a drug as well as whether the drug is better than current treatments. Phase III studies involve hundreds to thousands of patients, and these advanced trials typically last several years. Many phase II and phase III studies are randomized; meaning that one group of patients gets the experimental

drug being tested while a second control group gets either a standard treatment or a placebo (that is no treatment, often masked as a ‘dummy’ pill or injection). Also, phase II and III studies are usually ‘blinded’- the patients and the researchers do not know who is getting the experimental drug. Finally, once a new drug has completed phase III testing, a pharmaceutical company can request approval from Food and Drug Administration (FDA) to market drug.

Table 1:

Projected figures in respect of revenue, human power and patient load for clinical research in India
	2003	2008	2010
Value (million USD)	50	200	1,000
Revenue (crore INR)	75	300	875
Full time staff requirement	800	4,000	20,000
Site-staff requirement	1,500	6,000	30,000

GCP guidelines for herbal drugs and products in conducting clinical trials in India¹⁸:

· It is important that plants and herbal remedies currently in use or mentioned in literature of recognized Traditional System of Medicine is prepared strictly in the same way as described in the literature while incorporating GMP norms for standardization. It may not be necessary to undertake phase I studies. However, it needs to be emphasized that since the substance to be tested is already in used in Indian Systems of Medicine or has been described in their texts, the need for testing its toxicity in animals has been considerably reduced. Neither would any toxicity study be needed for phase II trial unless there are reports suggesting toxicity or when the herbal preparation is to be used for more than 3 months. It should be necessary to undertake 4-6 weeks toxicity study in 2 species of animals in the circumstances pointed out in the preceding sentence or when a larger multicentric phase III trial is subsequently planned based on results of phase II study.

· Clinical trials with herbal preparations should be carried out only after these have been standardized and markers identified to ensure that the substances being evaluated are always the same. The recommendations made earlier regarding informed consent, subject, inducements for participation, information to be provided to the subject, withdrawal from study and research involving children or persons with diminished autonomy, all apply to trials on plant drugs also. These trials have also got to be approved by the appropriate scientific and ethical committees of the concerned Institutes. However, it is essential that such

clinical trials be carried out only when a competent Ayurvedic, Siddha or Unani physician is a co-investigator in such a clinical trial. It would neither ethically acceptable nor morally justifiable, if an allopathic physician, based on references in ancient literature of above-mentioned traditional systems of Medicine, carries out clinical evaluation of the plant without any concept or training in these systems of medicine. Hence, it is necessary to associate a specialist from these systems and the clinical evaluation should be carried out jointly.

· When a Folklore medicine / Ethno-medicine is ready for commercialisation after it has been scientifically found to be effective, then the legitimate rights/ share of the Tribe or Community from whom the knowledge was gathered should be taken care of appropriately while applying for the Intellectual Property Rights and / Patents for the product.

Critical Issues during Planning Clinical Trials

· As with drugs, an herb that is not toxic or therapeutic in one form or strength may be helpful or harmful in a different preparation²⁴.

· The potency of various compounds is affected by growing conditions, storage, handling, and preparation such that the potency of various products from the same plant can vary 10,000-fold²⁴.

· Knowledge of the nature of the preparations, and potential benefits and risks is necessary²⁵.

· Appropriate animal models are not available for validating claims of some very important and useful plant drugs like “Rasayana” enjoying esteemed repute in Ayurveda and termed in modern terminology as vitalizers, rejuvenators, adaptogens, and immunomodulators²⁶.

· Herbal medicines are prepared from materials of plant origin which are prone to contamination, deterioration, and variation in composition²⁷.

· Stored drug samples are prone to attack by harmful mycotoxin producing fungi. Detection to mycotoxins (aflatoxin B, acrilatoxin, citrinin and zearalenone) is certainly a matter of great concern in stored drugs of important medicinal plants²⁸, e.g. fruits of Embillica officinalis (1.51 µg/g); Terminalia chebula (1.19 µg/g)²⁹. S. Sapna et al., have developed a HPTLC method for the detection of aflatoxins B1, B2, G1 and G-2 from herbal raw materials. Studies revealed that caffeine acts as a good inhibitor of aflatoxins in stored samples³⁰.

· Many traditional medicines are claimed to exert their effects because each type of chemical compounds present may have a different activity and then seem of all of these may modify the action of the major “active” components³¹.

· Herb-Drug Interactions: Interactions between herbals and medications can be caused by either pharmacodynamic or pharmacokinetic mechanisms. Pharmacodynamic interactions can occur when an herbal product produces additive, synergistic, or antagonist activity in relation to the conventional drug with no change in the plasma concentration of either herbal product or drug³².The risk of having an herbal-drug interaction is based on a variety of factors and not solely based on the pharmacologic and pharmacokinetic characteristics of the herbal³³. Experimental data, case reports and case series regarding herb-drug interactions are limited³⁴. For e.g. Non-steroidal anti-inflammatory drugs (NSAIDs), particularly aspirin, have the potential to interact with herbal supplements that are known to possess antiplatelet activity (ginkgo, garlic, ginger, bilberry, dong quai, feverfew, ginseng, turmeric, meadowsweet and willow), with those containing coumarin (chamomile, motherworth, horse chestnut, fenugreek and red clover) and with tamarind, enhancing the risk of bleeding³⁵.

Table 2: Transition in regulatory authority capabilities in India²⁰

Before 2005	After 2005
Process patent law	Product patent for drugs, food and agrochemicals
Phase II and III trials were only permitted after those phases were completed elsewhere (Phase lag)	Schedule Y amended for multi-centric concurrent clinical trials as per GCP Upgraded Schedule M
	Clinical trial registry - India (CTRI), funded jointly by DST, WHO and ICMR initiated
	GLP monitoring authority set up for pre- clinical (toxicological) studies
	New drugs, imports, clinical trials, drug standards approved by Central Government Enforcement by States
	CDSCO-WHO National Pharmacovigilance Programme Launched

· Batch to batch variations start from the collection of raw material itself in the absence of the any reference standards for proper identification, and multiply during storage and further processing. Multiple markers and biomarkers may help in this problem²⁷.

· Analysis of phytoconstituents required advanced sophisticated analytical techniques to measure these compounds qualitatively and quantitatively. Chromatographic printing technique can be used for the assessment of the quality consistency and stability of the herbal extracts or products by visible observation and comparison of the standardized fingerprinting pattern. Fingerprinting of the herbals can be done by HPLC, HPTLC, MS, LC-MS, H¹NMR, etc. Apart from this there are some methods to evaluate the fingerprint quality of herbal materials or pharmaceutical products, such as correlative chromatography, comparative analysis, wavelet analysis and artificial neural networks (ANN)³⁶. Moreover, extracts of plant obtained can be loaded on the TLC plate and are developed in suitable solvent system. By using different solvent systems, derivatization of the plate to obtained distinct coloured spots and scanned under different conditions which utilizes laser beam or UV at different wavelengths pattern can be optimized to give distinct HPTLC profile for each fractionated plant part³⁷.

CONCLUSION:

A small number of herbal medicines have been shown to have a more favorable safety profile than conventional drugs of similar effectiveness on the basis of comparative clinical trials³⁸. An example of comparative trials is the randomized controlled trials in patients with depression; the frequency of adverse effects with extracts of St John's wort was significantly lower than that for the conventional antidepressants³⁹. Further, in randomized controlled trials in men with benign prostatic hyperplasia (BPH) similar observations have been reported for extracts of saw palmetto, when compared with finasteride⁴⁰. The benefit-risk comparisons must be made for each case, as it cannot be assumed that this will apply to all comparisons of herbal medicines and conventional drugs. Nor should it be assumed that a benefit-risk analysis is applicable to all preparations of a particular herb. As with evidence of efficacy, evidence of safety should be considered to be extract-specific or, at most, extended only to preparations of the same herb with a very similar profile of constituents.

Thus, the development of herbal medicines from the rich traditional source requires an integrated approach. This includes cultivation and procurement of raw material involving the producer to minimize the misidentification and contamination, manufacturing of the finished product with application of good manufacturing practice guidelines, and validating the therapeutic potential of the drugs by conducting controlled clinical trial with application of good clinical practices guidelines. The advantages of traditional systems of medicine with respect to their safety and efficacy could result in a better utilization of our herbal resources with application of the scientific methods.

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Received on 25.03.2008 Modified on 30.05.2008

Research J. Pharm. and Tech. 1(2) April-June. 2008; Page 69-74