Opiates constipation

Morphine has certain undesirable side effects. Among these are respiratory depression, nausea, and vomiting, depression of the cough reflex, cardiovascular depression and hypotension, smooth muscle contraction (constipation), and histamine release (93). Morphine s onset of action, duration, and low therapeutic indices have prompted a search for a more effective opiate iv anesthetic. Extreme simplification of the complex morphine molecule has resulted in anilido —piperidines, the fentanyl class of extremely potent opiate iv anesthetics (118,119). 

There are a number of side-effects of opiates that are due to their actions on opiate receptors outside the central nervous system. Opiates constrict the pupils by acting on the oculomotor nucleus and cause constipation by activating a maintained contraction of the smooth muscle of the gut which reduces motility. This diminished propulsion coupled with opiates reducing secretion in the gut underlie the anti-diarrhoeal effect. Opiates contract sphincters throughout the gastrointestinal tract. Although these effects are predominantly peripheral in origin there are central contributions as well. Morphine can also release histamine from mast cells and this can produce irritation and broncho-spasm in extreme cases. Opiates have minimal cardiovascular effects at therapeutic doses. 

Opiates Monitor patients for sedation and depressed cognition. Address constipation with use of stimulant laxatives. 

Acute physiological responses to opiate administration occur rapidly and include constricted pupils, decreased pulse rate, reduced body temperature, slowed respiration rate and impaired reflexes. In addition, there is a marked slowing of the digestive system through an altering of the tonus and motility of the stomach and intestines, allowing for greater water absorption. This last effect is not subject to tolerance, and constipation is a common side effect even for chronic users. Indeed, some report that this is the worst side effect of opiate use. 

Opium and its derivatives have been employed for centuries for the treatment of pain. Morphine was first synthesized in 1805 and has proven to be one of the most effective analgesic agents available [1], Morphine and its analogs are particularly useful because they diminish pain sensation while maintaining consciousness. However, opiates induce severe side-effects including respiratory depression, nausea, bradycardia and constipation and long-term use of opiates can cause addiction [2]. 

Constipation commonly results from a diet low in fiber or from use of constipating drugs such as opiates. Constipation may sometimes be psychogenic in origin. 

All opiate derivatives are associated with constipation, but the degree of intestinal inhibitory effects seems to differ between agents. Orally administered opiates appear to have greater inhibitory effect than parenterally administered agents oral codeine is well known as a potent antimotility agent. 

In the hospitalized patient without GI disease, constipation may be related to the use of general anesthesia and/or opiate substances. Most orally or rectally administered laxatives may be used. For prompt initiation of a bowel movement, a tap-water enema or glycerin suppository is recommended, or milk of magnesia. 

It is unlikely that these agents are effective in preventing constipation if major causative factors (e.g., heavy opiate use, uncorrected pathology, inadequate dietary fiber) are not concurrently addressed. 

Methadone is not without side effects. Although it is less addictive than other opiates, methadone can be abused and requires monitored use. Common side effects include sedation and constipation. Methadone is also safer than other opiates in overdose but does require careful monitoring of respiratory status when an overdose occurs. 

Constipation may be caused by slow intestinal transition, pelvic floor dysfunction, bowel dysfunction like irritable Bowel syndrome and tumours, but can also be secondary to other diseases and life conditions. Many medicines cause constipation, for example opiates, calcium channel blockers and drugs with anticholinergic effects, e.g. antidepressants. 

Symptom patterns those with alternating constipation and diarrhoea and predominant constipation may benefit from high fibre diets (although excess fibre may bloat). Those with predominant diarrhoea may require simple peripheral opiate agonists (loperamide), but may also be helped by raised fibre intake. Pain may respond in part to explanation that it does not indicate serious illness and in part to spasmolytic therapy with anticholinergic agents which... 

Geriatric Considerations - Summary Diphenoxylate is an analog of meperidine and can cause opiate adverse effects. When discontinued, physical dependence and withdrawal symptoms can occur. Adverse GI effects such as constipation, nausea/vomit-ing, and abdominal pain may result from normal doses. Afropine is added to discourage abuse but can cause anticholinergic adverse effects in the older adult. The benefits of f his drug combination for older adulfs are limifed by fhe risk of adverse effects. 

There are three principal classes of opiate receptors, designated x, K, and 5, and there exist a number of drugs that are specific for each of these receptor types. However, most of the clinically used opiates are quite selective for the preceptor the endogenous opiates enkephalin, endorphin and dynorphin are selective for the p and 5, 5 and k receptors respectively. When activated by opioids these receptors produce biochemical signals that block neurotransmitter release from nerve terminals, a process that underlies their blockade of pain signaling pathways as well as other effects, such as constipation, diuresis, euphoria, and feeding. 

There are many peripheral organs that possess enkephalin opiate receptors the ileum, the most distal part of the small intestine, and the vas deferens are the most significant. The receptors in the ileum are responsible for the antidiarrheal activity of opiates. This is also the explanation for the severe constipation that may occur when people use opiates for pain relief. 

Codeine, which is an opium alkaloid is most commonly opiate used as antitussive and more selective for cough centre. Like morphine, it depresses cough centre but is less constipating and abuse liability is low. It is relatively safe drug used in cough along with analgesic property and it s only important adverse effect is constipation. 

Opiates produce constipation by affecting receptors in the intestines. Opium extracts were used in this capacity to treat diarrhea. Today there are other related compounds on the market which accomplish the peripheral task without affecting the CNS because of their poor absorption from the Gl tract when taken orally. Imodium A-D , an OTC, contains loperamide. It is also available as a generic OTC. The prescription mixture of diphenoxylate and atropine is called Lomotil . 

Anileridine, ethyl l-(4-amino phenethyl)-4 phenylisonipecotate is available in the form of its dihydrochloride for oral administration and as the phosphate for injection (Leritine ). Its analgesic potency is intermediate between that of meperidine and morphine. Similar to meperidine, it exerts mild antihistaminic and spasmolytic effects, but it is devoid of the constipating effect of opiates. Sedative and direct hypnotic effects are similar to those of meperidine but less than those of morphine. 

The opiates cause constipation by inducing spasm of the stomach and intestines, presumably by the stimulation of opioid receptors in the myenteric plexus and reducing the release of acetylcholine. This property can be used therapeutically for the symptomatic relief of diarrhoea. Biliary colic and severe epigastric pain can occur because of the contraction of the sphincter of Oddi and the resulting increase in pressure in the biliary ducts. 

Codeine, hydrocodone, and hydromorphone decrease the sensitivity of CNS cough centers to peripheral stimuli, and decrease mucosal secretion. These actions occur at doses lower than required for analgesia (see p. 135 for a more complete discussion of the opiates). Dextromethorphan [dex troe meth OR fan], a synthetic derivative of morphine, suppresses the response of the cough center. It has no analgesic or addictive potential, and is less constipating than codeine. 

Reduce the senna dosage to 1-2 tablets once daily initially (also check Mrs CR s current bowel habits if diarrhoea then senna should be stopped, ffowever, as Mrs CR will continue to receive opiate analgesia then it is likely that prophylactic laxative therapy will need to be continued, due to opiates causing constipation in almost all patients). Monitor Mrs CR s bowel habits during her inpatient stay in order to ensure the appropriateness of the laxative therapy. 

Q4 Constipation can be a troublesome side effect of opiates used for pain relief, for example morphine and codeine. It is also a side effect of some calcium channel blocking agents, antacids containing aluminium compounds and iron salts used in the treatment of anaemia. 

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