The expansion of prescribing by non-medical healthcare professionals is likely to benefit people with long-term conditions such as diabetes, ensuring that care is both effective and convenient. Given the increasing rates of diabetes, managing it and its complications will be an important part of the workload for many new prescribers.

All prescribers need a good knowledge and understanding of pharmacology and how it influences decisions about the choice of drug; the route of administration, dose and frequency; and the management of potential contraindications, side-effects and interactions with other drugs. Pharmacological treatment of diabetes aims to regulate blood glucose levels using insulin, insulin-stimulating drugs or insulin-enhancing drugs.

This chapter examines the fundamentals of pharmacokinetics – how drugs move within the body and are affected by it – and pharmacodynamics – the effects drugs have on the body and what moderates these effects. It highlights issues to consider when assessing clients before prescribing medication, using examples from the treatment of diabetes and its complications.

Routes of administration

Drugs can act either locally, mainly after topical administration, or systemically, mainly after oral or parenteral (see below) administration. If a drug acts locally, its effects are confined to a specific area; systemically acting drugs enter the vascular and lymphatic systems for delivery to body tissues. It is possible, however, for topical drugs to have systemic effects, especially if doses are large, frequent or administered over a long period.