The more frequent and numerous the prescription of drugs in a particular setting, the more the risk of an error occurring. It is well documented that most medication errors occur in Intensive Care Units, Pediatric Intensive Care Units (because of the wide ranges of patients in terms of age and weight, and requirement for weight determined dosing), and in the elderly patients.

In the prescribing of drugs, knowledge about the drug is a prerequisite to enable proper drug and dosage order. Adequate information about the patient is necessary (e.g. history of drug allergy) to avoid the use of the drug concerned. Drug dose must be adjusted for patients with disease states like hepatic and renal dysfunction.

The written prescription is usual in traditional practice, so illegibility and error prone methods of writing dosages are rife (e.g. writing of 1.0 mg can easily be mistaken as 10 mg, and use of wrong units). Abbreviations are also factors in drug errors – q.d. or once daily can easily be mistaken for q.i.d. which is four times daily. Providers must be particularly mindful of errors due to drugs with similar sounding names (e.g. Zyrtec and Zantac) and drugs which look alike or are put into look-alike packaging.

After transcription of the written prescription, the drugs are dispensed. This involves accurate compounding of the drug in the proper dose, form and timing. Drugs can be incorrectly formulated at this stage.

Administration errors occur when drugs are dispensed to the wrong patient, in an inappropriate dose or form and at the wrong time. These errors are generally human errors which tend to occur more frequently in busy units where nurses are stressed, overworked or inexperienced, as well as in the operation theatres when anesthetists often administer multiple drugs in often highly stressful situations.

The response to a drug must be monitored by providers with the assistance of the patient so that in the event that an adverse reaction does occur, appropriate adjustment or change in the drug administration can be effected. Documentation of such adverse drug effects is important to avoid similar errors in future.

The publication of the eye-opening paper “To err is Human” spurred efforts to minimize the occurrence of medication errors (as well as medical errors) through establishment of organizations to look into and manage every aspect of patient safety, such as Centers for Patient Safety and Institute for Safe Medication Practices. Error reporting processes that were voluntary and confidential were set up to determine the full extent of the occurrence of errors, thus enabling steps to be taken to address factors responsible for them. Information was shared and experts helped identify best practices to be implemented. Regulations and guidelines were formulated to improve safety compliance and training programmes conducted to train personnel in safety issues.

A systems based approach was established to improve conditions of patient medication, to make it difficult for errors to occur. Basically the environment in which health care is provided and the people working within it interact as a complex and dynamic functioning unit or system. Parts of the system relate to each other directly or indirectly. All systems have processes that transform inputs (e.g. ill patients) into outputs (e.g. healthy individuals). So, systems based approaches allow us to focus on the processes in the system and to use key target measures to evaluate and improve these processes in the system.