Azithromycin in primary care

Dr Brian O’Doherty looks at the treatment of bacterial infections in the primary care setting

It is currently an opportune time to talk about the use of antibiotics, what with the increased instance of respiratory tract infections. Good clinical practice and other pressures, such as financial constraints, force us to consider our role in prescribing antibiotics and the appropriateness of doing so.
This winter, it has been compounded by the fact that as well as the ordinary flu virus and other atypical infections, we have the advent of the H1N1 influenza outbreak. This has caused a lot of confusion and a greater workload. There is also a great opportunity, perhaps, for patient education as most seem to realise now that antibiotics do not have a great role against viruses.
I must declare my interest in writing this article, as I have been involved in numerous international clinical trials on the use of azithromycin in a community setting. I have conducted multicentre clinical trials for sinusitis, chronic bronchitis, pneumonia and acute tonsillar infections for Pfizer International.
It is very well documented that respiratory-tract infections are one of the most common reasons to attend the primary care service. It is estimated that 25 per cent of the population visits their GP on an annual basis with the condition.
As a result, this is very time-consuming and there are a wide variety of decisions that must be made with regard to the treatment. This is because of differences in expectations as regards the modality of treatment between patient and physician. One must remember that there have been very few new antibiotics developed over the last ten years, particularly those that could be of use in primary care.
It is therefore very important that we use them appropriately. There are numerous studies that show that patient education can ease the burden of the expectation of prescribing. We can also use other strategies such as a delayed or withheld prescription.
Atypical infections
However, one must remember that this year – with all the presentations with myalgia, temperatures and atypical clinical signs – we must also think of the atypical infections such as mycoplasma, legionella and chlamydia.
These conditions respond very well to Zithromax. There is also excellent coverage of the normal bacteria that cause infection in the respiratory tract, i.e. Streptococcus pneumoniae, Moraxella catarrhalis or Haemophilus influenzae. In the guidelines for the treatment of community-acquired pneumonia, Zithromax is one of the drugs of choice, as it gives very good coverage for these particular pathogens.
There are numerous guidelines from different societies and azithromycin is recommended by almost all of them for community-acquired pneumonia/acute exacerbation of chronic bronchitis.
Zithromax is readily-absorbed and reaches peak levels quite rapidly. It is concentrated in the tissues and particularly well in mucus membranes. The tissue levels are much higher than the actual blood levels. The result of having such high tissue levels probably accounts for its clinical efficacy at the site of infection. It is also concentrated in the neutrophils, which migrate to the site of infection.
Azithromycin is a macrolide and is the related to erythyromycin. The modality of action is to prevent protein synthesis.
In general practice, there is now only beginning to be an awareness that we should have more guidelines for the treatment of common infection. This is being proposed by numerous agencies.
However, the problem is that most treatments for community-acquired pneumonia are for seven-to-ten days, on an empirical basis. It is probably much easier to treat patients for a shorter period of time such as a five-day course, which usually is more than adequate.
One of the main benefits of Zithromax is that it is only a once-daily dosage for three days. As a result of this, compliance is almost guaranteed. This is a huge issue with other antibiotics.
One study showed that up to 50 per cent of patients did not complete their courses of antibiotics and up to 38 per cent still had an antibiotic that was used again at a later stage. This would be a definite recipe for resistance and is something that should be discouraged.
Summary
In summary, azithromycin is a broad-spectrum macrolide antibiotic that is ideal for the treatment of respiratory tract infections.
It has proven action against all the major respiratory pathogens and is also active against the atypical pathogens. Due to its pharmacokinetics, it has a once-daily dose for three days, which greatly aids compliance. It has been shown to be equivalent to ten days’ treatment with other comparable antibiotics in the treatment of chronic bronchitis and pneumonia.
In this current season, I think it is one of the antibiotics that should be considered in treating respiratory tract infections.