The word placebo comes from Latin meaning "I shall please". The placebo as defined in the reliable website is "an inactive substance resembling a medication, given for psychological effect or as a control in evaluating a medicine believed to be active". The word 'Placebo' in a standard dictionary has two meanings - either a medicine given to humour rather than to cure patient or a substance usually used as a way of testing the effect of a medicine given to others. The placebo phenomenon is not of recent discussion topics. The history of medicine is a history of placebo. There is growing interest in placebo phenomenon in medicine and in psychology as well. A book, "The Powerful Placebo (1997)" by Shapiro, A. K. and Shapiro E claims that the placebo has always been the norm of medical practice and the history of medical practice is a history of the dynamic power of the relationship between physician and patient. Throughout the annals of medical history, the belief in the doctor and the treatment has always been of paramount importance. The doctor believed in the treatment, the patient believed in the doctor, the person got better. Various medical researches from time to time show that people actually start to feel better once they meet the physician.
In a recent meta-analysis study comparing 110 homeopathy trials with matched conventional-medicine trials, the details of which appeared in Lancet (Shang A et al, Lancet 2005; 366(9487):726-32), it was found that there is weak evidence for a specific effect of homoeopathic remedies, suggesting that clinical effects of homoeopathy are placebo effects. This research report has revived interest and curiosity in placebo phenomenon among academics and health care professionals. The influence of the placebo effect in alternative medicine field has been debated for many years. Critics of alternative medicines often explain placebo effect is the answer of how homeopathy, acupuncture, faith healing, chiropractic, osteopathy and other treatments work.
We find placebo related medical achievements in every country and in every epoch. Clearly, each magic and empiricism played an important role in employing remedies. The ancient Egyptian healers recommended dung and excrements to repel bad spirits that caused diseases. In China, acupuncture has been practised for more than 2500 years. In India, the cornerstone of medicines was the mantra, kavacha, fasting and abstinence from sex, non-vegetarian foods and materialism. Paracelsus (Swiss alchemist and physician), in the 15th Century, observed that medicine killed and nature healed. Voltaire (French author and philosopher, 1694-1778) wrote, "The art of medicine consists in amusing the patient while the nature cures the illnesses".
It is a well recognised fact today that placebo effects can result simply from contact with physicians or other health professionals; even simple attention from them alleviates anxiety. In this context, I like to narrate two incidents from my own experiences. During my visits in my small native towns, I used to spend most evenings in a nearby known clinic. Many friends and contemporaries of the health care practitioner used to meet him on their way back home. They casually asked him for medicine(s) to get rid of their headache, sleeplessness, loss of appetite or anxieties. He always gave two sodamint tablets to be taken at night and morning. The following day all of them would be happy to tell him about their drastic improvements in conditions. In the early 1980s, when I was staying in a PG hostel in Kolkata, one day a hostel mate asked me if a tablet is there for sleep (as he was not having proper good sleep for a week). I gave him one-fourth of a paracetamol (calpol brand) tablet with the advice to take it just before going to bed as the tablet is very potent. The next day, to my surprise, he complimented both my judgement and the tablet, which helped him sound sleep. The effect is obvious i.e. placebo effect.
Contrary to the popular believe, placebos can have side effects and can be harmful. This is nocebo effect. One reason of nocebo effect is someone who disbelieves in a treatment may experience a worsening of symptoms. Surveys of the literature suggest that about one-quarter of patients taking a placebo spontaneously report discomforting side effects.
Placebos in clinical trials
Placebos have one very important role in medicine i.e. in clinical drug research trials. Placebo-controlled studies are the standard for establishing therapeutic efficacy of a new treatment (drug). Researchers use placebos in clinical drug trials in which a "test group" of subjects receives a drug being tested, and a "control group" receives the placebo. Regulatory agencies approve new drugs only after placebo-controlled studies establish not only that patients respond to them, but also that their effect is greater than that of a placebo. However, there are pitfalls of placebo-controlled studies. In certain clinical trials of particular drugs, it may happen that the level of the "placebo responses" manifested by the control's subjects are either considerably higher or lower (in relation to the test). In addition, placebo studies can pose an ethical dilemma for clinical trial involving serious life-threatening illnesses in which patient must receive active treatment.
Recent debate points out that the placebo and the placebo effects are far more ubiquitous than commonly thought. There is a plethora of literature available on placebo. A keyword search on "placebo" using 'scirus wed search' results 193890 references. In the context of recent withdrawal of anti-arthritis drug rofecoxib (Vioxx) from market, a clinical trial study revealed that compared to placebo, people taking Vioxx for at least 18 months had double the risk for cardiovascular events. Certainly, people may follow Paracelsus, who once said: "You must know that the will is a powerful adjuvant of medicine."
(The author is Reader in Pharmacy, Annamalai University, Annamalainagar 608 002, Tamil Nadu).