An introduction into week two, understanding antibiotics and their resistance.
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.
This is an additional video, hosted on YouTube.
Interestingly, the G in penicillin G (or benzylpenicillin) comes from the term ‘gold standard’ (when named, it was the best penicillin available).
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
)-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.