Principles of drug administration: Administration of medicines per rectum


Chapter 22

Principles of drug administration


Administration of medicines per rectum



Medicines inserted into the rectum have two predominant actions:



The rectum can be a useful route for the administration of some medicines if the woman is nil by mouth, unconscious, or vomiting. This chapter reviews the correct procedure and discusses the role and responsibilities of the midwife.




The rectal route


This is a commonly used route for the administration of some medicines, but it is not always the most popular route for patients. The superior rectal vein drains the upper part of the rectum, while the inferior rectal veins drain the lower part. The lining of the rectum is delicate. Medicines can be well absorbed but there are potential dangers: rupturing the mucosa, infection and haemorrhage. The nearness of some of the branches of the vagus nerve in the rectum means that a bradycardia can be induced; extreme care is taken with any women needing a suppository who have an existing cardiac condition. There may also be inconsistencies in the amount of drug absorbed via the rectal route: the inferior rectal veins enter the circulation directly (lower rectum), facilitating faster drug absorption. From the upper rectum the superior rectal vein transports medication via the liver; the absorption systemically is slower. The presence of faeces in the rectum can also reduce drug absorption. The midwife should observe the woman for any signs of under- or overdose following P.R. drug administration (Jordan 2010).


Bradshaw et al (2009) suggest that any administration of suppositories or enema should be preceded by a digital rectal examination. This includes a risk assessment: particularly in understanding the client’s medical history, examining the perianal area, assessing anal sphincter tone, and noting the presence/absence of faeces in the rectum. A digital rectal examination should be carried out by an appropriately trained and competent practitioner. The author would suggest that the majority of maternity clients are unlikely to need this level of ongoing intervention, those that do should be cared for jointly by obstetric and gastroenterology teams. However, an appreciation of the client’s history, and of any perianal anomalies, e.g. perineal trauma, anal sphincter damage, haemorrhoids, genital warts, helminthic infection, are clearly significant factors that impact on the suitability of administering medication P.R.



Suppositories


The medication is contained within the pellet that dissolves at body temperature in the rectum. Sometimes ongoing use of suppositories can irritate the bowel; this often relates to whichever melting substance is used. Lubricating the suppository makes its insertion easier and improves the comfort for the woman. The instructions should be checked, some need lubricating with water alone, e.g. glycerin suppositories (BNF 2014).



Which way are they inserted?


The shaping of suppositories has traditionally suggested to practitioners that they should be inserted tapered end first. There is, however, a debate about this. Abd-el-Maeboud et al (1991) considered the anatomy and physiology of the rectum and believed that inserting a suppository blunt end first would facilitate its retention better than if inserted tapered end first. This caused a change in practice (Moppett 2000), but Kyle (2009) has questioned this change. Kyle (2009) considers that Abd-el-Maeboud’s trial had a dubious methodology and that changes to practice that are based on an isolated study should be made cautiously. Abd-el-Maeboud et al (1991) suggest that if the suppository is inserted blunt end first the anatomy of the rectum ‘sucks’ the suppository in as the sphincter closes, whilst inserting a suppository tapered end first prevents the anal sphincter from closing properly. The manufacturers continue to suggest that tapered end first is correct in line with their product licence (Bradshaw & Price 2007). Johnson & Taylor (2010) supported the idea that suppositories for systemic use should be inserted blunt end first while laxative ones should be inserted tapered end first. As Kyle (2009) suggests, if this issue is of considerable significance then further rigorous research is needed promptly. The reader should be aware of the devolving argument, any future studies and their locally agreed protocol.

Only gold members can continue reading. Log In or Register to continue

Oct 17, 2016 | Posted by in MIDWIFERY | Comments Off on Principles of drug administration: Administration of medicines per rectum
Premium Wordpress Themes by UFO Themes