Opioids which are extracted from opium are mixture of alkaloids from the poppy plant- Papaver Somniferum. Opiods are very commonly used in anesthesia and in intensive care unites. Their mechanism of actions at cellular level is by activating opoid receptors,these receptors are distributed throughout the central nervous system (CNS) and there main purpose of use in ICU are relieving pain (analgesic) and to some extend they are also sedatives. They are prescribed for patients in ICU who require strong relief from severe pain for more than a few days. It can become addictive if not administrated correctly. The three commonly used opioids in ICU are morphine, hydromorphine and fentanyl, where as fentanyl is also basically use for induction during general anesthesia.
Fentanyl which is a synthetic opioid is hundred times more potent than morphine which means it can act much more faster than morphine and that's why it is also administered in combination with benzodiazepine, such as midazolam , to produce procedural sedation for endoscopy, cardiac catheterization, oral surgery, etc. Fentanyl is often used in the management of chronic pain including cancer pain. Fentanyl dermal patches are also used for treating chronic pain. The patches release fentanyl into the body fat which then slowly releases it into the blood stream over period of 42 to 78 hours. Fentanyl does not detemine the release of histamines, which means they do not produce severe hypotension compared to morphine.
In well developed countries, new methods which are known as patient control analgesia (PCA) are used but these methods are only effective for patients who are conscious. In PCA, patient can administer himself a dose of opioids whenever the intensity of pain is high in a set time frame. The patient cannot exceed a certain dose in that time frame. PCA allows the patient to administer the dose of opioids during acute pain and this has been proven more efficient and successful. The opioids for intravenous use PCA may include morphine, meperidine, hydromorphone, and fentanyl but usually morphine is used more traditionally in PCA. According to research fentanyl has less side effects as compared to morphine (headaches, nausea, vomiting, urinary retention)
The common side effects of opioides are nausea, nose tip itching, , drowsiness , itching, dry mouth, miosis, and constipation but when used in excess and during abuse can cause adverse effects like respiratory depression,confusion ,hallucinations, delirium , urticaria , hypothermia , bradycardia, orthostatic hypotension, dizziness, headaches, ureteric or biliary spasm, muscle rigidity, myoclonus , flushing and addiction.