Abstract In this article in the series of ‘bite sized’ pharmacology, we will look at the concept of drug action- the therapeutic effect of the medications we give. It is important that prescribers are aware of factors that can affect drug action and the time to onset of and subsequent duration of the desired therapeutic effect. We will look at factors that affect these two important areas of drug action. Knowledge of these factors can assist the prescriber when deciding on doses and dose schedules to ensure that patients receive their medications at the correct dosing, by the correct route and in the right formulation to ensure optimum therapeutic effect. It also helps the prescriber understand why dose adjustments are made or some drugs are avoided in patients with hepatic or renal impairment.

The article uses a case study to give examples of calculations that may be encountered with patients who have Alzheimer's dementia and benzodiazepines

This article contains a case study on calculations related to the safe use of lithium

The article uses a case study to test common calculations skills related to the use of antipsychotics including clozapine

In this second article in the series of ‘bite sized’ pharmacology we will start to look at the principles of pharmacodynamics. It is important that prescribers are aware of the actions their drugs have in the body after administration. They should know the SITE of action (where the drug works), the MODE of action (how the drug works) and the time to ONSET and DURATION of action (when the drug starts to work and how long for). This helps prescribers decide on drug choice, drug dose and the dose schedule as well as the length of time the drug needs to be prescribed for. This knowledge can also assist the prescriber in prediction and prevention (or minimising) of adverse drug reactions and to help educate their patients on possible side effects. In this article we will look at SITEs of action; receptors, ion channels, enzymes, and transport systems. We will also introduce the concepts of agonism and antagonism and their relationship to MODE of action.

Pharmacology is an area many nurse prescribers tell me that they worry about. This is whether they are prescribing students or qualified prescribers. They are very aware of the importance of pharmacological knowledge and its impact on safe prescribing. They typically want to know how much information they need to know and what depth and breadth that information should take. Another area they worry about is how many drugs they need to be familiar with? This series of pharmacology articles will explore some concepts in pharmacology to support the prescriber in developing that knowledge. This article begins by examining the basic concepts of pharmacokinetics to allow the reader to improve their understanding of drug handling within the body. It will explore the processes of absorption, distribution, metabolism and excretion to chart a drugs ‘route’ from administration to elimination.

In this article in the series of ‘bite sized’ pharmacology, we will look at the concept of first pass metabolism. All drugs given by the oral route undergo a degree of first pass metabolism either in the gut or the liver, with some drugs being destroyed before they reach the systemic circulation. This pharmacokinetic process affects the bioavailability of drugs administered by this route and is an important consideration for the prescriber. Knowledge of first pass metabolism can assist the prescriber when deciding on doses and dose schedules to ensure that patients receive their medications at the correct dosing, by the correct route for optimum therapeutic effect. It also helps the prescriber understand why dose adjustments are made for some drugs when switching the route of administration from oral and why some drugs cannot be given by the oral route.