Activated charcoal drug can protect microbiome from antibiotics

By Jessica Hamzelou

Antibiotics can save your life, but they can also mess up your microbiome. A special formulation of activated charcoal could help, protecting your body from the side effects of antibiotics, and perhaps even aiding the fight against antibiotic resistance.

The side effects of a course of antibiotics – such as stomach pains and diarrhoea – are familiar to many. But by messing with the balance of microorganisms in a person’s body, they may also cause longer term changes, potentially leading to obesity, allergies and eczema. And by killing too many of the good bacteria in your gut, they can make way for harmful and even drug-resistant bacteria, such as C. difficile, which is responsible for around 30,000 deaths a year in the US.

Jean de Gunzburg and his colleagues at Da Volterra, a biotech company based in Paris, think they have found a solution. Activated charcoal – a super-absorbent material – is routinely used to soak up excess drugs in the guts of people who have overdosed, and they have evidence that a modified version could do this for antibiotics.

Protective effect

To stop charcoal from simply soaking up an entire dose of oral antibiotics, the team coated tiny pieces of activated charcoal with a special covering. This breaks down by the time the charcoal reaches the large intestine – which hosts a rich ecosystem of beneficial bacteria – allowing it to mop up any antibiotics that make it this far and protect the bacteria.

The team tested its slow-release activated charcoal, named DAV132, in a clinical trial of 44 healthy volunteers. A five-day course of the common antibiotic moxifloxacin was given to 28 people, half of whom also took DAV132 twice a day throughout the treatment, and for two extra days at the end. A further eight volunteers took DAV132 on its own, while eight people took nothing at all.

De Gunzburg’s team found that DAV132 didn’t affect how much of the antibiotic made it into a person’s bloodstream, suggesting that it wouldn’t stop the drug from killing off a bad infection. However, the faeces of the people who took DAV132 with the antibiotic had only around 1 per cent of the level found in the faeces of those who took the antibiotic on its own, suggesting the charcoal mopped up the antibiotic in the large intestine.

The drug also seemed to protect gut bacteria. Around 250 species of bacteria reduced in number in the guts of those who took antibiotics alone. “Close to 90 per cent of those species were protected by our product,” says de Gunzburg.

The team didn’t look at whether DAV132 reduced the incidence of side effects from taking antibiotics, such as diarrhoea.

No side effects

“The results are promising,” says Willem van Schaik at the University of Birmingham. “It’s a really exciting approach to protect the microbiome from antibiotics.”

So far, the team have seen no bad side effects from taking the charcoal. “The faeces become dark, but that’s the only consequence,” says de Gunzburg. But before their product becomes more widely available, the team want to see if it can stop resistant bacteria from developing. It’s also possible that the charcoal might soak up important other compounds in the gut.

De Gunzburg plans to start testing the charcoal in people taking antibiotics to treat infections next year. In the meantime, people shouldn’t give themselves regular activated charcoal, as this could simply stop their antibiotics from working.

Journal reference: bioRxiv, DOI: 10.1101/169813