Antibiotics are an essential aspect of modern day healthcare. They have lead to a rapid increase in life expectancy and great advances in medicine since their discovery.

A list of some antibiotics commonly found in a typical community pharmacy and their antibiotic class:

• Penicillins (e.g., amoxicillin, co-amoxiclav, flucloxacillin, phenoxymethylpenicillin)

• Macrolides (e.g., azithromycin, clarithromycin, erythromycin)

• Cephalosporins (e.g., cefalexin)

• Fluoroquinolones (e.g., ciprofloxacin)

• Tetracyclines (e.g., doxycycline, tetracycline)

• Nitrofurans (e.g., nitrofurantoin)

• Diaminopyrimidines (e.g., trimethoprim)

• Nitroimidazoles (e.g., metronidazole)

• Chloramphenicol

Antibiotics can be used to treat both acute and chronic infections. Their use can be prophylactic e.g., surgery or for treatment. They come in several medicinal forms (e.g., capsule, tablet, suspension, cream, eye drops) depending on their clinical indication and the patient themselves.

Key notes

This is a brief overview of antibiotics and some important things to note when dispensing them…

Tetracycline antibiotics + antacids: Do not take milk, indigestion remedies, or medicines containing iron or zinc, 2 hours before or after taking this medicine. Why? These antibiotics form complexes known as chelates with metal ions found in milk and antacids meaning that the antibiotic is less effective. This interaction is avoided by spacing antacids and tetracyclines at least 2 hours apart.

Tetracycline antibiotics: Tetracycline antibiotics such as doxycycline can make patients sensitive to sunlight. Patients should be advised to avoid sun beds and use sun protection.

Metronidazole + alcohol: Avoid alcohol while taking this medication and for at least 48 hours after stopping treatment. Why? Alcohol causes a disulfiram-like reaction when given with metronidazole. Side effects of this interaction include nausea and vomiting, stomach pain, hot flushes, palpitations and headaches.

Nitrofurantoin: This antibiotic is soluble in urine and can impart its brown colour to a patient’s urine. The patient should be reassured that this is harmless.

Chloramphenicol: Eye drops should be stored in the fridge.

Penicillin antibiotics: Always check patients for a penicillin allergy before dispensing.

Antibiotic suspensions: Some antibiotics come as powder for reconstitution into a suspension e.g., phenoxymethylpenicillin, flucloxacillin, amoxicillin. These antibiotic suspensions have a very short shelf-life due to the relative instability of their active ingredient in the liquid form. These should be made up to the correct volume using a measuring cylinder immediately prior to dispensing and used within the stated shelf-life on the box. The antibiotic should also be stored in the fridge once it has been reconstituted and throughout its use. The patient should be advised to shake the bottle well before each use to uniformly disperse the antibiotic so that a uniform dose is achieved.

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