Pharmacovigilance of Herbal Products

Herbal formulations are being widely accepted therapeutic agents as antidiabetics, antiarthritics, hepatoprotectives, cough remedies, memory enhancers, and adaptogens. The most common myth regarding herbal medicines is that they are completely safe, and can therefore be safely consumed by the patient, without a physician’s prescription. This belief has led to large-scale self-medication by people all over the world, often leading to disappointing end-results, side-effects, or unwanted after-effects. There is an increasing awareness at several levels of the need to develop pharmacovigilance practices for herbal medicines. The current model of pharmacovigilance and its associated tools have been developed in relation to synthetic drugs, and applying these methods to monitoring the safety of herbal medicines presents unique challenges in addition to those described for conventional medicines. Several problems relate to the ways in which herbal medicines are named, perceived, sourced, and utilized. This may be because of differences in the use of non-orthodox drugs (e.g., herbal remedies) which may pose special toxicological problems, when used alone or in combination with other drugs. The purpose of pharmacovigilance is to detect, assess, and understand, and to prevent the adverse effects or any other possible drug-related problems, related to herbal, traditional, and complementary medicines.

Pharmacovigilance standards

Pharmacovigilance is the science and activities relating to the detection, assessment, understanding, and prevention of adverse effects of drugs or any other possible drug-related problems. Recently, its concerns have been widened to include herbals, traditional and complementary medicines, blood, and biological products. The purpose of pharmacovigilance is to detect, assess, and understand, and to prevent the adverse effects or any other possible drug-related problems, which is not only confined to chemical drugs, but extended to herbal, traditional, and complementary medicines, biologicals, vaccines, blood products, and medical devices.

The history of the use of herbs as medication is very old, with some researchers stating that the first recorded use of herbs for medical treatment began over 4000 years ago. The origin of this type of medical treatment began in China and India. Traditional Chinese medicine centres on interactions between the body and the environment. A mixture of treatments, including herbs, acupuncture and massage, is then prescribed. Traditional Indian medicine has dated back to 3000 BC, and the most popular form is Ayurvedic. A combination of European, Chinese, Ayurvedic and other unconventional treatments influenced the use of herbs to the present day. In almost all the traditional systems of medicine, the medicinal plants play a major role and constitute their backbone. Adverse events may also arise from the misuse of the wrong species of medicinal plants, incorrect dosing, errors in the use of herbal medicines by healthcare providers and consumers, interactions with other medicines, and use of products contaminated with potentially hazardous substances, such as toxic metals, pathogenic microorganisms, and agrochemical residues.

The following examples demonstrate the range of problems encountered with the use of herbal medicines and products.

  • Some herbal products were found to contain 0.1 to 0.3 mg of betamethasone per capsule after some patients developed corticosteroid-like side effects
  • Owing to misidentification of the medicinal plant species, plant materials containing aristolochic acid were used for manufacturing herbal products, which caused severe kidney failure in patients in several countries
  • Reports have been received by drug safety monitoring agencies of prolonged prothrombin times, increased coagulation time, subcutaneous hematomas, and intracranial hemorrhage associated with the use of Ginkgo biloba
  • One of the most well-known traditionally used herbal medicines caused severe, sometimes fatal cases of interstitial pneumonia, when used in conjunction with interferon

Need of pharmacovigilance in herbals

In order to provide consistency in the naming of herbs in adverse reaction (AR) reports, the WHO Collaborating Centre for International Drug Monitoring has recommended the use of proper scientific binomial names for herbs used in medicine, including the use of such names (where this information is available) in the coding of AR reports. This would ensure comparability between reports from various international pharmacovigilance databases. It is equally important for the authors of published AR case reports to identify the specific product involved, including label and manufacturer information, specific ingredients, and dose employed. Published case reports would also benefit from analysis of the suspect product used, for contamination and adulteration, or species identification, where possible. A lack of, or incorrect, herbal identification has been noted as a potential source of confusion in published case reports of HMP toxicity.

Herbals concept of adverse reaction

An AR is defined as a noxious and unintended response to a marketed health product, which occurs at doses normally used or tested for the diagnosis, treatment, or prevention of a disease or the modification of an organic function. It is undeniable that plants have an important role in the development of modern medicines. More than 60 to 70% of modern medicines in the world market are directly or indirectly derived from plant products. High-profile issues such as ARs associated with Ephedra and Aristolochia have shown that HMPs can produce toxicity in human beings. The most common adverse effects reported are hepatic and renal problems. However, it is difficult to identify the causative agent associated with the ARs encountered because traditional herbal preparations often contain multiple ingredients. The WHO database has over 16,000 suspected herbal case reports. Due to the lack of clinical trials for most HMPs, post market pharmacovigilance is a critical source of safety information; however, the assessment of ARs associated with HMPs offers unique challenges in the quantity and quality of available information.

The quality of ARs depends in part on educating potential reporters of what types of data are valuable for assessment. Such educational efforts can take the form of online educational modules, such as those directed at naturopathic doctors.

Recommendations

There are several ways to move forward in attempting to provoke pharmacovigilance in herbals.

  1. Introduce pharmacovigilance concepts into the curriculum of herbals at the undergraduate and postgraduate level
  2. Make reporting of adverse reactions to regulatory mandatory for herbal formulations
  3. Train herbal experts in the science of pharmacovigilance and include them not only in reporting but also in assessment of the adverse reactions

Fraternity Efforts

Healthcare professionals should remain vigilant for potential interactions between herbals and prescription medications, especially when it involves medications with narrow therapeutic indices. Due to the wide use and easy availability of herbal medicines, herbal toxicity has become an issue of concern. The safety and quality of herbal medicine should be ensured through greater research, pharmacovigilance, greater regulatory control, and better communication between patients and health professionals. The recommended approach is to include herbal medicines in existing national pharmacovigilance systems or, where such systems have not yet been developed, to establish comprehensive national pharmacovigilance systems which incorporate coverage of herbal medicines. Pharmacovigilance in herbal medicine in India is perhaps an unthought of concept as yet; we must not need a disaster to wake the pharmacovigilance community to the need of the hour.

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