Are underrecognized and underreported adverse effects of Amoxicillin making it a less safer drug?

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Amoxicillin: is an antibiotic used to treat many different types of infections caused by bacteria, such as tonsilitis, bronchitis, ENT nfections etc.

Treatment with amoxicillin-clavulanic acid ( B lactamase inhibitor) commonly causes diarrhea and candidiasis.

In the Canadian Medical Association Journal, Malcom Gillies, PhD from NPS Medicine wise, Sydney, Australia & colleagues disseminated their systemic review and meta analysis of randomized trials.The objective was to evaluate the clinical trials and to inform clinicians about the harmful effects caused by amoxicillin in order to help them make more careful decisions before prescribing this drug.

Study: 45 clinical trials were reviewed by Dr Del Mar (of Bond University in Gold Coast Queensland, Australia ) and his colleagues.Out of which 17 were on amoxicillin- clavulanic acid, 27 on amoxicillin and 1 on both. Only 25 trials provided enough data to enable the authors to evaluate the harms of this antibiotic and the authors deduced that the adverse reactions caused by this drug were underreported in medical proclamations or publications.

A range of conditions were included:

  • Dental care 20% (9studies)
  • Primary care 23% (15 studies)
  • Prevention 20% (20 studies)
  • Treatment 56% (25 studies)

The total number participants was 10,519 with 4,280 receiving amoxicillin, 1,005 receiving amoxicillin- clavulanic acid and 5,234 were on placebo.` Researchers discovered that nearly twice as many people taking amoxicillin had diarrhea when compared with those who were on placebo & diarrhea was over 3 times as likely in people who were taking amoxicillin- clavulanic acid.

The results revealed the number of courses of antibiotic to cause harm was 10 for diarrehea with amoxicillin- clavulanic acid and 27 for candidiasis with amoxicillin (with or without clavulanic acid).

Prolonged use of this medicine can cause oral thrush or a new vaginal yeast infection. So, a patient needs to contact his/her physician or pharmacist if they experience white patches in mouth, or changes in vaginal discharge.

According to Dr Del Mar, the important consequence of insuffiucient reporting of harms is the tilting of the balance of benefits and harms toward amoxicillin.

According to the researchers other common side effects such as GI disturbances and rashes have been fully reported but the above mentioned adverse effects werent fully reported.

The researchers also found surprising facts from the study that there was no significant increase in the rashes, nausea, vomiting, itching or abnormal liver function tests.

And now the researchers are suggesting that quality assessment tools for adverse events be included into clinical trials to submit the claim of  “no significant harm” to the same extent that efficacy claims receive.

Resistance: according to CDC, amoxicillin have been used in the treatment of infectious diseases since 1940s. Around 2 million people in US each year develop infections due to bacteria that are now resistant to antibiotics. And the common cause of antibiotic resistance is the over use and unnecessary use of antibiotics and this will keep on increasing until and unless the antibiotics are prescribed only by fully considering their benefits and harms.

The researchers believe that “the absence of evidence of harm” is not same as “evidence of absence of harm” for such drugs.

The studies are showing that antibiotics are being readily prescribed for the respiratory infections and they often provide only minor benefits, so in such cases the risks and benefits should be weighed carefully before using them.

The evidence of common adverse effects is insufficient because most of the data is not obtained from the randomized controlled trials but is collected from the observational studies.

Conclusion: So this shows that by the help of clinical studies in children and adults, in both males and females will give a better picture on the harms of amoxicillin and in return will help the physicians in prescribing the antibiotics after carefully deciding whether the benefits outweigh the risks or not.

Reference:

CMAJ.

US Pharmacist.

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