Pharmaniaga Fentanyl Side Effects

Respiratory system: Depending on dosage, fentanyl causes respiratory depression up to apnoea, lasting normally only a few minutes at low doses, but many hours at high doses. The respiratory depressant effect may last longer than the analgesic effect and may re-occur in the postoperative period.
Postoperative monitoring is therefore compulsory.
Furthermore, laryngospasm and in single cases bronchospasm was observed. Airway conductance may be impaired by glottic closure through glottic rigidity. In single cases, pulmonary oedema has been described after fentanyl.
Central nervous system: Besides sedation, vertigo, euphoria, nausea and vomiting may also occur.
In rare cases cerebral seizures were observed. Administration of fentanyl over a longer period of time may cause the development of tolerance. The development of drug dependence cannot be ruled out. After infusions of fentanyl of long duration in children, movement disturbances, increased sensitiveness and opioid withdrawal symptoms have been observed.
Cardiovascular system: Fentanyl may cause bradycardia up to cardiac arrest and a decrease in blood pressure, especially in hypovolaemic patients. Bradycardia can be treated by administration of atropine.
Orthostatic regulatory disturbances may occur.
Musculoskeletal system: An increased tension of skeletal muscles (muscle rigidity), especially thoracic stiffness resulting in impaired ventilation can occur, as well as myoclonic movements.
If muscle rigidity is occurring, the application of muscle relaxants is advised.
Various organ systems: The opioid specific effect on smooth muscles may lead to constipation, increased muscle tone of the ureter resulting in urinary retention, especially in patients with prostatic hypertrophy, and spasm of the sphincter of Oddi.
Fentanyl may cause miosis and disturbances of vision.
Allergic reactions like anaphylaxis, pruritus and urticaria may occur.
Sweating and singultus are further side effects which have been observed after the application of fentanyl.
Methemoglobinemia can occur.