Dr Ron Eccles Outlines the Challenges of the Placebo Effect for Cough Medicines

Patients may find a placebo effect beneficial, but it causes issues in a clinical trial and makes it difficult to understand the efficacy of a pharmacological agent, said Ron Eccles, BSc, PhD, DSc, emeritus professor at Cardiff University.

Transcript:

Is there any benefit to the placebo effect in chronic cough?

There's a huge benefit: to the patient. If you are giving a medicine that has a lot of sensory impact, for example, most of the medicines you can pick up at your Walmart or your pharmacy, they made as viscous sweet setups. They have warming agents in, cooling agents in, menthol in, and they taste very medicinal, and that increases the magnitude of the placebo response. So, those medicines are really very good medicines, even without any pharmacological efficacy. They don't need the pharmacological efficacy; the patient believes the medicine is active, the anticipation is that they will have relief, and relief is what they get.

So, when you actually come to market these medicines and give them out, having a big placebo effect is greatly beneficial to the patient. However, in a clinical trial situation, where you're trying to measure the pharmacological efficacy, it confounds the clinical trial and makes it impossible to measure the pharmacological efficacy.

The placebo effect has been used in cough medicines for hundreds of years. And we used to bleed patients, we used to put leeches on them, we used to give them medicines that made them vomit and made them sick. And the patients all actually felt better as regards cough or anything else, because of the placebo effect.

Now, if you are trying to study pharmacology, the placebo effect confounds the clinical trials, it makes it very difficult to study the pharmacological effect of a medicine, if the trial is unbalanced, and the trial is likely to be unbalanced, because of side effects. Unfortunately, it's very difficult to get rid of the side effects with many medicines, and therefore, we don't have matched placebos.

There are many studies that have been conducted on psychoactive drugs. The psychoactive drugs cause a dry mouth. So, atropine has been used as a positive placebo, where you can create a dry mouth in the placebo arm. Unfortunately, the atropine, used as a placebo, has been found to be just as active and sometimes more active than the psychoactive drugs. Again, confounding the clinical trials because of its powerful placebo effect.