.a. Describe the differences between local and systemic routes of drug administration, giving examples of each. (7)
Outline the actions a nurse can take to minimise the occurrence of side effects of drugs. (7)
1a) Local routes of administration will result in an effect to the area where the drug has been administered, whereas systemic routes of administration result in absorption into the circulatory system and so can affect the entire body. For example, local routes of administration include eye drops and ear drops, these medications will only have an effect on the eyes and ears respectively and will not enter the circulatory system to have an effect elsewhere. Additionally, this is also true of drugs administered by inhalation (nebulisers, inhalers) as they well only have an effect on the respiratory system and not elsewhere. Conversely medication administered orally will be absorbed at some point in the digestive system and so enter the circulatory system, an example of systemic administration. A further example of this route of administration is injection, as the drug is injected directly into bodily tissue it can take an effect on the entire body as it will be absorbed into the circulatory system quickly (or immediately in the case of intravenous administration).
b) One of the most important actions a nurse can take in order to minimise the effects of drugs is to take observations following administration, such as blood pressure, for example tricylic antidepressants can cause orthostatic hypotension. Observing respiratory rate can also be useful if a patient has been administered an opioid analgesic. A nurse can also ensure that the patient receives a drug to reduce the side effects of another drug, for example giving cyclazine to combat the nausea effects of morphine.
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Compare and contrast the actions of agonist, partial agonist and antagonist drugs. You should illustrate your answer with examples. (14)
2) When an agonist drug bonds to the receptor on a cell it may produce a range of effects, as the drug is able to bind to the receptor and cause an effect it is an agonist, for example when Morphine bonds to a neuronal cell in the brain it might cause nausea, respiratory distress or an analgesic effect dependant on what dose was administered, as the drug causes an effect from binding to a receptor it is an agonist.
This in contrast to an antagonist drug which, while still binding to the same receptors, will not produce a response. An antagonist can be used as an ‘antidote’ to agonist drugs, in the case of morphine the antagonist would be Naloxone. Naloxone will bind to the same receptors that morphine would bond with but the Naloxone will not cause a response and will not allow morphine to bind to that receptor and so will inhibit the action of morphine.
Finally there are partial agonist drugs, these drugs are similar to agonists but they do not have as many effects as agonists do as they cannot cause as much of a response from the receptors as agonists do. Still looking at opioid drugs, Buprenorphine is an example of a partial agonist. It has a similar analgesic effect to morphine but is less likely to cause respiratory distress and so doesn’t offer as many effects, and so is only a partial agonist. Partial agonists also have a ceiling effect in that unlike an agonist where the higher the dose, the more the effect. When an agonist is administered it binds to the receptor which causes the release of endorphins as do partial agonists, however when the dose is increased in an agonist the amount of endorphins released increases too, partial agonist do not have the same effect with regard to endorphins and so the drug effects are ‘capped’.
A client who has severe chronic obstructive pulmonary disease is prescribed oxygen via a controlled-flow mask to provide a concentration of 24%, whereas another patient who has severe acute asthma is prescribed oxygen via a high-flow mask to provide a concentration of 60%.
Explain the rationale for the differences in the oxygen prescriptions for these two clients. (14)
4) Those with COPD will have damage to the alveoli of the lungs and so may have emphysema, as the alveoli are damaged the surface area in which O2 and CO2 are exchanged is greatly reduced, this results in a low blood oxygen concentration and a higher blood carbon dioxide level. If a patient with this condition is given high flow, high concentration oxygen the respiratory rate may drop and the alveoli will have difficulty in transferring the oxygen to the blood and so the levels of carbon dioxide will rise. This effect will result in a lack of oxygen in the brain cells and so the patient will become disorientated and eventually comatose. This can be avoided by giving oxygen at a lower concentration such as 24% because this will allow the damaged lungs to exhale CO2 rather than retain it, this should result in the alveoli having an improved gaseous exchange. This is also why a controlled-flow mask should be used, as the stream of oxygen is controlled the lungs will not be over-filled with oxygen that they cannot use which would again result in an increased CO2 concentration in the blood as the alveoli will still struggle with the exchange. However in a patient with acute asthma the problem is not that the alveoli cannot exchange oxygen or that CO2 is being retained, it is that insufficient oxygen is reaching the alveoli in the first place due to obstruction caused by inflammation or bronchospasm. In this case it is important that the amount of oxygen in the lungs is increased so that the alveoli can exchange the oxygen and in turn increase the saturation of oxygen in the blood. To do this quickly it is important that high-flow oxygen is used at a high concentration as this will increase the volume of oxygen quickly, allowing the gaseous exchange in the alveoli to return to normal.
Laxatives are frequently administered by nurses.
List the FOUR groups of laxative drugs. (4)
Choose any TWO of these groups, explain their actions and side effects and provide at least one example from each group. (10)
6a) Bulk laxatives, Stool Softners, Osmotic Laxatives, Stimulant laxatives.
6b) Osmotic – These laxatives make stools softer by increasing the amount of water in the bowels. They can be given in the form of liquid or dissolved powder. Lactulose for example achieves this by being broken down by bacteria in the bowel which results in the production of acids. These acids then cause the contents of the bowel to become more fluid, as a result the stools are softened, lactulose also has the effect of mildly irritating the bowel, when this is combined with its osmotic effect, a laxative effect is produced. This however does cause some side effects, because of the increase in fluid in the bowels diarrhoea can occur. It also takes a couple of days to have its full osmotic effect and so flatulence and distention are common side effects.
Stimulant – These laxatives all contain anthraquinone emodin which is a purgative resin, this resin is released in the intestines and there it is absorbed into the bloodstream and begins to act on the large intestine causing muscle contraction (peristalsis), this peristalsis is what makes them stimulants. They are available in forms including tablets, suppositories, granules and syrups. The most commonly used example of a stimulant laxative is Senna, this works as has just been described and like osmotic laxatives may cause diarrhoea, further side effects of stimulant laxatives include griping pains and malabsorption.
Explain the actions of selective and non-selective non-steroidal anti-inflammatory drugs (NSAIDs). You should include their mode of action, effects and side effects and give examples where appropriate. (14)
7) Non-selective NSAIDs are used to reduce inflammation in rheumatoid arthritis and to reduce pain without causing sedative effects. Aspirin reduces the production of the lipid prostaglandin, this results in analgesia and the reduction of inflammation. Aspirin works by the inhibiting the ability of cyclooxygenase (both COX-1 and COX-2) to produce the prostaglandins in the first place, as these are responsible for the constriction and dilation of muscle cells and the sensitivity of spinal neurons to pain their removal will reduce both inflammation and pain. One problem with this action however is that the prostaglandins have a protective effect in the gastrointestinal tract and so their removal can result in gastric irritation as a side effect. Diclofenac is a good example of a non-selective NSAID as it is used to reduce inflammation in pain but causes irritation to the gastric tract which can ultimately lead to a gastric ulcer. More commonly it will result in indigestion, diarrhoea and headaches.
Pharmacology -Nursing Exam Questions & Answers
