tag:theconversation.com,2011:/id/topics/asprin-11191/articlesAsprin – The Conversation2015-12-10T11:17:52Ztag:theconversation.com,2011:article/478952015-12-10T11:17:52Z2015-12-10T11:17:52ZWhen is an aspirin a day to prevent heart attacks too risky?<figure><img src="https://images.theconversation.com/files/102904/original/image-20151123-18233-a5dyg7.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">What's the harm?</span> <span class="attribution"><a class="source" href="http://www.shutterstock.com/pic.mhtml?id=117314986&src=id">Aspirin via www.shutterstock.com.</a></span></figcaption></figure><p>We’ve known for a long time that aspirin can help prevent damage from a heart attack or a stroke if taken during one of those events. In fact, you might have seen ads about how aspirin can be lifesaving during a heart attack.</p>
<p>Research backs that up. For people who have already experienced a heart attack or stroke, a daily aspirin regimen can <a href="http://circ.ahajournals.org/content/130/25/e344">actually prevent</a> future <a href="http://journal.publications.chestnet.org/article.aspx?articleID=1159438">heart attacks</a> and strokes.</p>
<p>But, as helpful as aspirin is to prevent recurrent heart attacks or strokes (this is called secondary prevention), a daily aspirin has long been controversial to prevent a first heart attack or stroke (this is called primary prevention). </p>
<p>To use aspirin for primary prevention, doctors are supposed to assess a patient’s risk of a first heart attack or stroke and decide when benefits of aspirin outweigh risks. But new draft guidelines for aspirin use have created confusion about who, exactly, should actually take aspirin. </p>
<h2>What do the new draft guidelines say about aspirin?</h2>
<p>The <a href="http://www.uspreventiveservicestaskforce.org/Page/Document/draft-recommendation-statement/aspirin-to-prevent-cardiovascular-disease-and-cancer">new draft guidelines</a> from the United States Preventative Services Task Force recommend adults between the ages of 50-59 take aspirin if they have at least a 10% 10-year risk of having a heart attack or stroke as measured by a <a href="http://www.cvriskcalculator.com/">risk calculator </a>.</p>
<p>For people 60-69, the task force says there is less benefit compared to for those ages 50-59, but that aspirin should still be used as long as there is a low risk of bleeding as a side effect.</p>
<p>But for patients younger than 50 or older than 70, the task force decided there was not enough evidence to make a recommendation about using aspirin. This is a major departure from the 2009 recommendation, which suggested use in all adults between the ages of 45-79 with an elevated risk of a heart attack or stroke.</p>
<p>This change happened in part because of a push to make medical guidelines strictly evidence-based. Right now, there are no randomized trials comparing aspirin to placebo in adults older than 70 or younger than 50. Without evidence, you can’t have evidence-based recommendations.</p>
<p>Basing guidelines strictly on evidence makes sense, but clinical trials are rarely perfect, and recommendations on how to use drugs need to make sense to primary care providers in order to avoid confusion.</p>
<h2>What do the data say about aspirin for primary prevention?</h2>
<p>Early trials that treated patients with aspirin during a heart attack or stroke found they were more likely to survive. But these trials <a href="http://circ.ahajournals.org/content/130/25/e344">also found</a> that leaving patients on aspirin for months and years afterwards reduced future heart attacks and strokes. </p>
<p>For every 100 patients who’ve had a heart attack or stroke and stay on a daily aspirin, five recurrent heart attacks or strokes are prevented in the next year. While there is a small risk of serious bleeding with aspirin (mostly stomach bleeding, but also bleeding in the brain), fewer than one in 100 patients experience this. Therefore, everyone agrees that the benefits of aspirin outweigh the risks for people who have had a heart attack or stroke.</p>
<p>But for patients with no history of a heart attack or stroke, the <a href="http://dx.doi.org/10.1016/S0140-6736(09)60503-1">data say</a> that the risk of serious bleeds and the benefit of reducing heart attacks and strokes are about equal for a population of middle-aged and older adults. </p>
<p>According to the new calculations in the task force guidelines, for every 100 men 55-60 years old with an <a href="http://www.cvriskcalculator.com">average risk</a> of a first heart attack or stroke of 1% per year, starting a daily aspirin would have a <em>lifetime</em> effect of avoiding about two heart attacks and one stroke among those 100 men, but causing about three serious stomach bleeds and about one hemorrhagic stroke. </p>
<h2>What do the new guidelines mean for you?</h2>
<p>The draft guidelines from the Preventative Services Task Force might not offer a lot of clear yes’s and no’s about who should and shouldn’t take aspirin for primary prevention. And guidelines from other groups offer differing advice. </p>
<p>Guidelines from <a href="http://www.heart.org/HEARTORG/Conditions/HeartAttack/PreventionTreatmentofHeartAttack/Aspirin-and-Heart-Disease_UCM_321714_Article.jsp">The American Heart Association</a>, <a href="http://content.onlinejacc.org/article.aspx?articleid=1889061">American College of Cardiology</a> and <a href="http://care.diabetesjournals.org/content/33/6/1395.full">American Diabetes Association</a> all endorse aspirin for primary prevention in certain higher-risk patients. However, the Food and Drug Administration <a href="http://www.bmj.com/content/348/bmj.g3168">denied a petition</a> from the aspirin manufacturer Bayer Inc for wording on their label that said aspirin could prevent heart attacks and strokes for people who had never had them.</p>
<p>And the <a href="http://www.escardio.org/The-ESC/Press-Office/Press-releases/Last-5-years/Aspirin-still-overprescribed-for-stroke-prevention-in-AF">European Society of Cardiology</a> does not endorse aspirin for primary prevention for any patient – even those at high risk.</p>
<p>But, the “over-the-counter” availability of aspirin means that Americans, many Europeans and potential patients all over the world can decide for themselves whether or not to take aspirin. And many are deciding to do so. A national survey that <a href="http://www.ajpmonline.org/article/S0749-3797(14/)00661-8/fulltext">we published in 2015</a> showed that nearly half of all US adults without CVD indicated that they “regularly” used aspirin as a preventive therapy. </p>
<p>So what should patients do? If you are over the age of 40 and don’t have a history of cardiovascular disease, check your predicted <a href="http://www.cvriskcalculator.com/">10-year risk of CVD</a>. </p>
<p>If your individual risk is greater than 10%, talk to your doctor about taking aspirin. Patients who don’t have a risk of bleeding could be considered good candidates for therapy, but they should understand that the odds of a serious bleed are about the same as the odds of preventing a heart attack or stroke. Not all patients will want to take the trade-off. </p>
<p>For patients who are under 70 with a CVD risk of less than 10%, aspirin therapy should generally be avoided. </p>
<p>While it is widely believed that these new task force recommendations will cut down on how many people go on an aspirin regimen in the US, that remains to be seen. It depends whether busy primary care providers read and agree with the guidelines, and then translate them into clinical practice.</p><img src="https://counter.theconversation.com/content/47895/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Craig Williams does not work for, consult, own shares in or receive funding from any company or organization that would benefit from this article, and has disclosed no relevant affiliations beyond their academic appointment.</span></em></p>New draft guidelines for using aspirin to prevent heart attacks have created confusion about who, exactly, should actually take it.Craig Williams, Professor of Pharmacy, Oregon State UniversityLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/321942014-10-09T09:48:39Z2014-10-09T09:48:39ZHow thalidomide became one of the most talked about drugs in cancer therapy<figure><img src="https://images.theconversation.com/files/61148/original/mgh69qc7-1412762862.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Dark past, but looking to the future.</span> <span class="attribution"><a class="source" href="https://www.flickr.com/photos/darwinbell/83485181/sizes/l/in/photolist-8nTeF-cUBoE-5CsLU-51yd8-51zgZ-5YsFg-51ydb-pvJee-51fBf-51g22-51g2o-89wk4-5jWYi-32s4Vq-5jWYj-6yaxcK-cUsC6-5jWY5-7ShPi-5jWUG-4QQyU-poQBe-5jWYc-4R5DR-finwZ-5jWY8-8rULmn-AQi4b-6NeWvg-aYzhn-aDCgG-5sBGy-5sBFR-4R5G8-eWAkXy-4QQPs-4QQsD-4R5EV-PftQA-4R5CT-AVdp3-KdeGV-eWoUrK-eWAjJb-eWoRRc-eWAiaC-eWAmQb-eWoSTa-eWoTp2-fabdxH-5v8G9/">Darwin Bell</a>, <a class="license" href="http://creativecommons.org/licenses/by-nc/4.0/">CC BY-NC</a></span></figcaption></figure><p>Innovative new drugs to treat cancer frequently make the headlines, either due to great success or controversy, as pharmaceutical companies get lambasted for selling the drugs at too high a price for state systems to afford.</p>
<p>But alongside this high-budget pharmaceutical research is a different tactic being quietly waged in the background: investigating old, inexpensive drugs, originally designed for a variety of maladies, to see whether they might be able to treat cancer – essentially, repurposing old for new. </p>
<figure class="align-left ">
<img alt="" src="https://images.theconversation.com/files/61152/original/m5q98rwm-1412764022.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/61152/original/m5q98rwm-1412764022.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=452&fit=crop&dpr=1 600w, https://images.theconversation.com/files/61152/original/m5q98rwm-1412764022.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=452&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/61152/original/m5q98rwm-1412764022.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=452&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/61152/original/m5q98rwm-1412764022.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=568&fit=crop&dpr=1 754w, https://images.theconversation.com/files/61152/original/m5q98rwm-1412764022.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=568&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/61152/original/m5q98rwm-1412764022.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=568&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">What else can these do?</span>
<span class="attribution"><a class="source" href="https://www.flickr.com/photos/epsos/8119248181/sizes/l/in/photolist-dntgBB-f4ozF8-eprZZH-7YJenQ-5ybjn2-9z7Esb-9bH4ur-2WWySF-7V1PRy-jR9gc-8Pomnt-oeNsPd-ovZbTK-aj2pWe-nS1dkA-oH4rdU-nRPvDM-nVncj9-nvA252-nui5G2-nHZFqF-ntBYA4-sCTxH-5fWrqu-oKTyND-oK4qob-nSw4Bx-nsjjC9-9d5WGV-4M7pV-nMoT1j-oDVBBT-6q9iv9-ncFSjE-aBH2Bg-nMdbka-78ePNM-bkbW8T-5S73oK-7kihrz-dErKR5-cqiNS1-c5Q5eb-vhNSP-4xWFPc-8c3Ug-4cXa6D-4VnZrY-8deFCr-4nVDsE-9Xcshz/">epSoS.de</a>, <a class="license" href="http://creativecommons.org/licenses/by/4.0/">CC BY</a></span>
</figcaption>
</figure>
<p>Repurposing Drugs in Oncology (ReDO), the international organisation aimed at promoting work in this area, defines repurposing as “the use of existing and well-characterised non-cancer drugs as new treatments for cancer.” ReDO believes that such drugs “may represent an untapped source of novel therapies”. Current candidates include diclofenac, an anti-inflammatory pain relief medication; clarithromycin, an antibiotic; and cimetidine, an antacid prescribed for stomach ulcers.</p>
<p>Cancers are increasingly being treated <a href="https://theconversation.com/how-science-is-using-the-genetics-of-disease-to-make-drugs-better-30747">on the basis of the mutations</a> that cause them, rather than where they are located. Seemingly distinct and unrelated cancers can arise due to the same genetic defect. Developing new drugs that target these mutations in a way that largely spares healthy cells is far from serendipitous and involves complex mathematical modelling and tens of thousands of laboratory hours to achieve even a prototype drug. All of this costs time and money.</p>
<p>Some researchers are shunning this process and instead turning to well-established drugs to improve cancer treatment. And it is an approach that is paying dividends.</p>
<h2>Rehabilitating thalidomide</h2>
<p>Infamous thalidomide, regrettably used to treat morning sickness in the late 1950s was catastrophic for developing foetuses and responsible for the birth of thousands of disabled babies. But despite this dark past, the potentially beneficial properties of thalidomide are being re-explored and it is currently one of the most talked about drugs in cancer therapy. More than 700 thalidomide clinical trials are currently registered in almost every cancer type imaginable and it is currently approved to treat a blood cancer called myeloma. </p>
<p>Although it isn’t fully understood how thalidomide works in cancer treatment, it is known to prevent the growth of new blood vessels, which can “starve” tumours and potentially cause them to shrink. There are other drugs which have similar properties, but many are expensive and come with a range of side effects. Thalidomide on the other hand is off-patent, cheap and relatively well evaluated.</p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/61151/original/5n8b5tzb-1412763695.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/61151/original/5n8b5tzb-1412763695.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/61151/original/5n8b5tzb-1412763695.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/61151/original/5n8b5tzb-1412763695.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/61151/original/5n8b5tzb-1412763695.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/61151/original/5n8b5tzb-1412763695.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/61151/original/5n8b5tzb-1412763695.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=503&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">100 years and counting.</span>
<span class="attribution"><a class="source" href="https://www.flickr.com/photos/aussiegall/4348697776/sizes/o/in/photolist-7ChdkS-5ACir-7fn1Ft-4iLkgb-9LVvkB-tAaQq-fxujXU-cokKLq-78dgxd-h6z1w2-khpF-fwpPW9-cncHUQ-cncZzy-Lox5K-bEDEz-v3Xxa-ds1TVY-7Vj6Lr-ab3wqX-cAb6zJ-9Wokj2-52Qb71-v9xvx-v9xvv-djNqXn-byWuu7-5baT2d-5b6A8K-ePr6yC-5ADPN-8PZkgJ-5ADSo-5NXog6-HGkW3-7FiETN-5E5bgc-64tE2t-ai718R-7TLnqF-61arse-v9Vv7-9wmVPN-CLqJJ-eiS8ev-4TzZPs-zpZn-3BrDcE-A6VD4-4dyUn6-5YcGKD/">Aussie Gall</a>, <a class="license" href="http://creativecommons.org/licenses/by/4.0/">CC BY</a></span>
</figcaption>
</figure>
<p>Aspirin, available commercially for more than a century, has also been investigated not only for its potential use in cancer treatment, but also in prevention. <a href="https://theconversation.com/profiles/jack-cuzick-97158">Jack Cuzick</a>, director of the centre for epidemiology at Queen Mary, University of London, <a href="http://annonc.oxfordjournals.org/content/early/2014/07/30/annonc.mdu225.abstract">led a research project</a> which earlier this year convincingly showed that daily aspirin reduces the risk of developing a variety of cancers and reduces the risk of dying from colon cancer by 40%. Cuzick practises what he preaches and has been taking aspirin daily for years, stating GPs “absolutely should recommend daily aspirin to all those over 50”.</p>
<p>These kinds of discoveries are not always made using educated guesses, and scientists often test thousands of drugs just to see if anything might work. Researchers at St Jude’s Children’s Hospital in the US <a href="http://www.stjude.org/stjude/v/index.jsp?vgnextoid=f582ccc3e3d77410VgnVCM100000290115acRCRD&vgnextchannel=363f2eecbf537410VgnVCM100000290115acRCRD&sc_cid=smd10029&sc_spid=92535816&linkId=9850037">recently tested</a> 1,300 existing medicines on medulloblastoma cells (a type of childhood brain cancer) in the lab. Two drugs typically used to treat breast cancer – gemcitabine and pemetrexed – were found to effectively kill these cells. A clinical trial has now been set up and researchers hope to improve a dismal cure rate of 40% in children with hard-to-treat medulloblastoma.</p>
<h2>Grunt work already done</h2>
<p>Alan Worsely, head of science communication for Cancer Research UK, said: “The advantage of re-using an existing drug is that much of the early work to find the correct dose of a treatment and discover any potential side effects is already done, so researchers can get on with finding out whether it can help cancer patients.”</p>
<p>Increasingly cheaper and quicker genetic testing methods mean that researchers are also now able to analyse the DNA of patients who respond atypically to normally successful treatments to figure out why. Childhood acute lymphoblastic leukaemia is one of <a href="http://leukaemialymphomaresearch.org.uk/patient-information/facts-blood-cancers">the success stories</a> of modern cancer treatment – 90% of children now survive for the long term. However, this still leaves 10% of patients who still die from the disease, mainly due to a relapse, which is very hard to treat. </p>
<p>Julie Irving, a reader in experimental haematology at Newcastle University <a href="http://www.bloodjournal.org/content/early/2014/09/23/blood-2014-04-531871.long?sso-checked=true">recently published research</a> showing that a drug called selumetinib, originally designed for tackling a faulty cell growth controlling pathway in lung and colon cancer, could be used to help children who relapse after treatment for acute lymphoblastic leukaemia but who also have the same faulty pathway.</p>
<p>The development of a new cancer therapy can cost <a href="http://www.sbns.org.uk/index.php/research/why-do-research/">upwards of a billion pounds</a> and take up to 15 years from initial development to reach patients. Mining the resource of thousands of “old” off-patent drugs is proving to be an important avenue in cancer treatment – and one which must be fully embraced by doctors and scientists.</p><img src="https://counter.theconversation.com/content/32194/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Victoria Forster does not work for, consult, own shares in or receive funding from any company or organisation that would benefit from this article, and has disclosed no relevant affiliations beyond their academic appointment.</span></em></p>Innovative new drugs to treat cancer frequently make the headlines, either due to great success or controversy, as pharmaceutical companies get lambasted for selling the drugs at too high a price for state…Victoria Forster, Postdoctoral Research Associate in Cancer Research, Newcastle UniversityLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/283622014-06-27T05:12:07Z2014-06-27T05:12:07ZNatural medicine is great, but chemists can make it even better<figure><img src="https://images.theconversation.com/files/52221/original/n2wp7hzf-1403691583.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Take one plant, tweak it a little...</span> <span class="attribution"><a class="source" href="https://www.flickr.com/photos/cifor/12184067924/sizes/l/in/photolist-jyEwUC-7Gu21k-7Gu1YV-aEXrSt-9sx2nc-7HwAC8-HNoiL-4NsDWE-9LHdBR-4PWPSg-5PtGSn-czjpp-4G3nUL-4tLvRd-64Jw9w-9pgKkf-6qYHis-2o38T-9tviGt-2knwZ-5UFDbW-6dp8KG-6dk18c-fniXzQ-9JGosk-4jTmMh-6A8JoK-7PeBhM-9A6VjQ-6hzf7J-bDGV3e-bnuJWa-6c4Wj8-6iHo7g-dCSR69-eoikuB-6zp9kb-5dwMte-bNKih8-bNKhUX-fNWAP-9yfeUo-7ULG7K-6PLSmn-bBrqsg-TmGi-6K5Xg6-5JLjZz-8qCCL1-mPVEx8-6oAC8o/">Cifor</a>, <a class="license" href="http://creativecommons.org/licenses/by-nc/4.0/">CC BY-NC</a></span></figcaption></figure><p>For years humans have searched for medicines in nature. While some seek “natural cures” in order to avoid chemicals, in truth everything is made up of chemistry. But as humans, we’re very good at manipulating what we find in nature – either through intention or accident.</p>
<h2>Penicillin: the antibiotic game changer</h2>
<p>The <a href="http://www.nytimes.com/2014/06/06/science/george-j-armelagos-anthropologist-who-told-skeletons-tales-dies-at-77.html?_r=0">late American anthropologist</a> George Armelagos showed 30 years ago that the inhabitants of ancient Nubia made their beer by <a href="http://news.nationalgeographic.com/news/2005/05/0516_050516_ancientbeer.html">fermenting grain that contained</a> streptomyces bacteria, which produces the antibiotic tetracycline. This in turn led to very low levels of infectious disease in the population. </p>
<p>But it wasn’t until the <a href="http://www.bbc.co.uk/history/historic_figures/fleming_alexander.shtml">accidental discovery</a> of penicillin by Alexander Fleming in 1928 and work done by Howard Florey and Ernst Chain in 1940 that led to the treatment of many wounded soldiers in World War II that the story of modern antibiotics really began. </p>
<p>There are many different molecules in the penicillin family – for example, Penicillin G, the substance made by Florey and Chain, contains 41 atoms. But all of them have the same core made up of two rings of atoms – mainly carbon atoms – fused together. Different molecules have different properties. One drawback of penicillin G was that it was broken up by stomach acid and could only be administered by injection.</p>
<p>But penicillin is manufactured by fermentation, and chemists found that they could produce penicillins with slightly different structures by changing the chemicals added to the fermenting broth. Different structures allowed researchers to produce penicillin, for example, that was stable to acid and allowed it to be taken by mouth. </p>
<p>It also subsequently became possible to mass-produce 6-aminopenicillanic acid – the molecule at the heart of the penicillin structure – and to then add side-chains of extra atoms to design a particular penicillin, like one that could tolerate threatening bacteria enzymes. This process is known as semi-synthesis – using the molecular structure from a natural source before adding “finishing touches”.</p>
<p>After the discovery of penicillin, there was intense interest in finding new antibiotics. The discovery of a molecule called chlorotetracycline (Aureomycin) in a sample of Missouri soil in 1945 led to a whole family <a href="http://www.rsc.org/chemistryworld/podcast/CIIEcompounds/transcripts/tetracycline.asp">of tetracycline antibiotics</a>. These now semi-synthetic products <a href="http://www.chm.bris.ac.uk/motm/doxycycline/doxyh.htm">include doxycycline</a>, effective against Lyme disease <a href="http://www.washingtonpost.com/wp-dyn/content/article/2010/02/19/AR2010021902369.html">and anthrax</a>.</p>
<h2>Ivermectin: the golf course find</h2>
<p>The 1970s yielding another important discovery from a microorganism named <em>Streptomyces avermectinius</em>, found in a soil sample from a seaside golf course by Japanese scientists. From this they isolated a molecule called avermectin, which proved active against numerous parasites. Still not satisfied, researchers made small tweaks to its structure to make it even more active. By dint of adding just two hydrogen atoms (to a carbon-carbon double bond) they <a href="http://www.who.int/apoc/cdti/ivermectin/en/">created ivermectin</a>.</p>
<p>Ivermectin is a tremendous success story <a href="http://www.rsc.org/eic/2013/11/ivermectin-river-blindness">in the treatment of river blindness</a> (onchocerciasis), a scourge of communities in tropical regions in the Americas and sub-Saharan Africa. This disease is <a href="https://theconversation.com/six-human-parasites-you-definitely-dont-want-to-host-17332">due to a parasitic worm</a> <em>Onchocerca volvulus</em> and is spread by certain black flies. A single dose of ivermectin every six months for the life cycle of the worms can keep the parasite at bay.</p>
<h2>Artemisinin: standing the test of time (just)</h2>
<p>An even greater scourge of sub-Saharan Africa is malaria, and the great discovery in the past half-century <a href="http://www.chm.bris.ac.uk/motm/artemisinin/artemisininh.htm">has been artemisinin</a>, obtained from the Chinese herb <em>Artemisia annua</em>. Artemisinin itself is not easily absorbed by the body so chemists have slightly altered its molecular structure and created new molecules – this is semi-synthesis at work again.</p>
<p>These have very similar structures to artemisinin but are more effective agents called arteether or artesunate. The latter of these can be administered intravenously for rapid action so is used against <a href="https://theconversation.com/new-twist-in-age-old-war-against-malaria-parasite-15856">acute cerebral malaria</a> where the disease spreads rapidly to the brain and can be fatal within three days.</p>
<p>But chemists can’t be complacent – the genes of the malaria parasite have <a href="https://theconversation.com/parasite-resistance-imperils-our-last-effective-malaria-drug-21685">shown an ability to adapt</a> to become resistant to artemisinin. And as one of the most effective remaining antimalarial drugs, resistance is a serious problem.</p>
<h2>Aspirin: the daddy of semi-synthetic</h2>
<p>And the daddy of all semi-synthetic drugs <a href="http://www.rsc.org/chemistryworld/podcast/CIIEcompounds/transcripts/aspirin.asp">is aspirin</a>. Back in the 18th century, an Oxfordshire clergyman named Edward Stone pioneered the use of willow bark in treating fevers; the bark contained a molecule called salicin, which in the body is transformed into the active compound, salicylic acid.</p>
<p>By the 1870s, salicylic acid itself was being used to treat fevers and pain, but digestive problems and ulcers were associated with its use. So chemists working for the German company Bayer converted it to acetylsalicylic acid, known today as aspirin, and that rapidly became the medicine of choice as an anti-inflammatory and painkiller.</p>
<p>Nature is the best synthetic chemist there is. It creates unbelievable molecules – both penicillin and artemisinin contain groupings of atoms that chemists thought could not exist – but they show that chemists can still improve on nature’s bounty and make amazing molecules that work even better in treating human ailments.</p><img src="https://counter.theconversation.com/content/28362/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Simon Cotton does not work for, consult, own shares in or receive funding from any company or organisation that would benefit from this article, and has disclosed no relevant affiliations beyond their academic appointment.</span></em></p>For years humans have searched for medicines in nature. While some seek “natural cures” in order to avoid chemicals, in truth everything is made up of chemistry. But as humans, we’re very good at manipulating…Simon Cotton, Senior Lecturer in Chemistry, University of BirminghamLicensed as Creative Commons – attribution, no derivatives.