Skip to 0 minutes and 6 seconds Antimicrobials, including antibiotics, have arguably been the most successful form of chemotherapy in the history of medicine. Antibiotics have helped control bacterial infections that were once leading causes of human death and so have saved millions of lives. Our tour of antibiotics starts by looking back in time and seeing how they evolved. From the concept of magic bullets, where a compound was viewed as a bullet to seek out and destroy an invading microorganism, through to the screening of vast numbers of coloured organic compounds, that act as dyes. Then on to the landmark discovery of penicillin G, by Fleming, in 1928, followed by the important work of Florey and Chain who, some 10 years later, developed an effective means of isolating penicillin G.
Skip to 0 minutes and 55 seconds Penicillin G is a member of a family of organic compounds with similar structures, that we call penicillins. We will explore the complicated structures of pencillins, how they are prepared in nature, and how they can be prepared in the lab. Importantly, we will investigate their interesting mode of action and how they interfere with the synthesis of bacterial cell walls - they indirectly lead to bursting of the cell walls. In 2010, a staggering 7.3 billion pills, capsules or ampoules, of penicillins were consumed worldwide. Unfortunately, humanity is helping to engineer a ‘superbug’ with the potential to kill hundreds of millions of people.
Skip to 1 minute and 38 seconds We will see that bacteria have the ability to mutate over time and become resistant to many medicines available to treat them, including penicillins. No new class of antibiotics has been found since 1987, and the lack of new medicines coupled with over-prescribing has led to bacteria becoming increasingly resistant. It is estimated that antibiotic resistance kills around 700,000 people per year around the world. The World Health Organisation has classified antimicrobial resistance as a ‘serious threat’ to every region of the world, which ‘has the potential to affect anyone, of any age, in any country’.
Skip to 2 minutes and 21 seconds Despite this, many major pharmaceutical companies have stopped research in this area, mainly due to economics - it can take over 12 years to discover and develop a medicine, costing more than £1.15 billion to do all of the research necessary for a medicine to be licensed for use - as antibiotics are used as a short course of treatment for bacterial infections, this reduces the commercial return of the investment. Nevertheless, the search for new medicines is never-ending, including research at York, and we will explore the range of antibiotics currently available, and importantly, some future directions of research. Let the race begin.
The race for new antibiotics
Antibiotic resistance is a growing cause for concern for us all. Experts warn of an impending catastrophic situation in which patients die following routine surgery due to infections that can no longer be treated. Among the superbugs of concern are strains of Staphylococcus aureus that are resistant to a number of antibiotics; these strains are called MRSA.
Antibiotic prophylaxis refers to the prevention of infection complications using antibiotics – these kill microorganisms or stop their growth (and this is called antimicrobial therapy). The most famous antibiotics are penicillins, a group of compounds with similar structures, which were among the first medications to be effective against many bacterial infections caused by staphylococci and streptococci. Most of you will have been prescribed a penicillin at some point (in 2013, it was suggested that as many as 80% of Americans are prescribed antibiotics annually), but you may not have been aware why an alternative name appeared on your prescription.
A name for every occasion
Traditionally, compounds were named based on their source, or on a property of the compound. For example, the name penicillin comes from the name of the mould Penicillium notatum, which produces it. The name Penicillium comes from the Latin word penicillus, meaning a painter’s brush, as the mould was thought to look like this.
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More recently, chemists devised and now use a systematic approach called IUPAC rules for naming compounds, based on their structure. For example, the IUPAC name for penicillin G is (2S,5R,6R)-6-(benzamido)-3,3-dimethyl-7-oxo-4-thia-1-azabicyclo[3.2.0]heptane-2-carboxylic acid – from this name, the chemical structure can be worked out. However, as it is so complicated, it is no surprise that we call it penicillin G and today, chemists tend to use a mixture of common and IUPAC names.
As the IUPAC names are often long and complicated, pharmaceutical companies use more concise and distinctive names to market their medicines, called the brand (trade or proprietary) names. For example, one manufacturer markets penicillin G using the brand name Pentids (notice the use of a capital letter for the brand name). Other manufacturers can make and sell penicillin G (it is off-patent) using different brand names, but generic names are more restricted. A generic name is assigned by an official body to identify the medicine and it is understood internationally – penicillin G is the generic name. So, a medicine has at least three different names – IUPAC, generic and brand names.
Many generic names are a shortened version of the medicine’s common or IUPAC name. In contrast, brand names are often catchy, sometimes related to a medicine’s intended use, and relatively easy to remember, so that doctors will prescribe the medicine and consumers will look for it by name. Brand names often suggest a characteristic of the drug. For example, Lopressor lowers blood pressure, Relenza provides relief from influenza, Skelaxin relaxes skeletal muscles, Tamiflu aims to tame flu and Wind-Eze aids indigestion and trapped wind.
What’s your favourite medicine name, and why?
By the way, with multiple names for the same medicine, it is no surprise there is confusion (the US Institute for Safe Medication Practices estimates that 25% of medication errors result from name confusion). So, to avoid confusion and medication errors, it is generally recommended that doctors use generic names when prescribing medicines, unless a specific reason exists. This can lead to cost savings because cheaper brands can be dispensed by the pharmacist. It may also avoid delay because the pharmacist can dispense a wider range of alternative preparations, rather than being limited to one brand, which may not be stocked.
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