Adverse effects of Fentanyl’s

The most common side effects of fentanyl affect more than 10% of people and include nausea, vomiting, constipation, dry mouth, drowsiness, confusion, and weakness (weakness).Less commonly, in 3-10% of people, fentanyl can cause abdominal pain, headache, fatigue, anorexia and weight loss, dizziness, nervousness, anxiety, depression, flu-like symptoms, dyspepsia (dyspepsia), Shortness of breath, hypoventilation, apnea, and urinary retention.Fentanyl use has also been linked to aphasia.Although fentanyl is a more potent analgesic,it tends to cause less nausea than morphine, as well as less histamine-mediated pruritus.Fentanyl’s duration of action is sometimes underestimated, leading to medical harm.In 2006, the U.S.Food and Drug Administration (FDA) began investigating several respiratory deaths, but physicians in the U.K. were not informed of the risks of fentanyl until September 2008. warn.FDA reported in April 2012 that 12 young children died and 12 others became seriously ill as a result of separate accidental exposure to fentanyl skin patches.

Respiratory depression 

The most dangerous side effect of fentanyl is respiratory depression,a decrease in sensitivity to carbon dioxide leading to a decrease in respiratory rate, which can lead to hypoxic brain damage or death.This risk is reduced when the airway is secured with an endotracheal tube (eg, during anesthesia).This risk is higher in certain populations, such as those with obstructive sleep apnea.

Other factors that increase the risk of respiratory depression are:

• High fentanyl dose

• Sleep

• Older

• Concomitant use of CNS depressants such as benzodiazepines, barbiturates, alcohol, and inhaled anesthetics

• Hyperventilation

• Reduces carbon dioxide levels in blood serum

• Respiratory acidosis

• Reduces clearance of fentanyl from the body

• Reduced blood flow to the liver

• Renal insufficiency

Sustained-release fentanyl formulations, such as patches, may also produce unexpected delayed respiratory depression.The exact cause of sudden respiratory depression is unknown, but there are several hypotheses:

• People with rapid and massive body fat loss have saturated body fat compartments (people with cachexia caused by cancer, heart disease or infection can lose 80% of their body fat).

• Early carbon dioxide retention leads to cutaneous vasodilation (release of more fentanyl), and acidosis, which reduces binding of fentanyl to proteins and releases more fentanyl.

• Reduced sedation, a useful early warning sign of opioid toxicity, resulting in levels approaching respiratory depression levels.

• Another associated complication of fentanyl overdose includes the so-called wooden chest syndrome, which rapidly induces complete respiratory failure by paralyzing the pectoral muscles, explained in more detail in the Muscle Stiffness.

• Heart and blood vessels

• Bradycardia:Fentanyl lowers heart rate by increasing vagal tone in the brainstem,which increases parasympathetic drive.

• Vasodilation:It also relaxes arterial and venous blood vessels through central mechanisms, primarily by slowing the vasomotor centers in the brainstem.To a lesser extent, it does this by directly affecting blood vessels.This is more severe in patients with already enhanced sympathetic drives, such as those with hypertension or congestive heart failure.When taken in regular doses, it does not affect the contractility of the heart.

Muscle rigidity

If a large bolus of fentanyl is given quickly, muscle stiffness in the vocal cords can make bag-mask ventilation very difficult.The exact mechanism of this effect is unknown, but it can be prevented and treated with neuromuscular blocking agents.

Wooden chest syndrome

A prominent heterogeneous adverse effect of fentanyl also includes sudden stiffness of the abdominal muscles and diaphragm, which can lead to respiratory failure; this is seen at high doses and is known as wood chest syndrome.This syndrome is considered the leading cause of death from fentanyl overdose.Wooden chest syndrome, which was reversed by naloxone, is thought to be caused by the release of norepinephrine, which activates alpha-adrenergic receptors and possibly also through activation of cholinergic receptors. Wood chest syndrome is unique to the most powerful opioids today including fentanyl and its analogs while other less potent opioids such as heroin cause mild stiffness of the respiratory muscles to a greater degree than much smaller.

Overdose

Fentanyl poses an unusually high risk of overdose in humans.This is because the amount needed to cause toxicity is unpredictable.In its drug form, most overdose deaths were attributed to fentanyl alone, with a mean serum concentration of 0.025 µg/mL and a range of 0.005–0.027 µg/mL.Blood fentanyl concentrations of approximately 7 ng/ml or higher were associated with death in the context of polysubstance use.More than 85% of overdoses involved at least one other drug, and there was no clear correlation at what level the mixture was lethal.In some cases, doses of the lethal mixture varied by more than three orders of magnitude.This wildly unpredictable volatility with other drugs makes avoiding death especially difficult.