Alfentanil

Indications

Alfentanil is used for: Adjunct in maintenance of general anaesthesia, Induction of anaesthesia, Analgesia in patients with spontaneous respiration

Adult Dose

Intravenous Adult: Incremental Injection: Anesthesia <30 Minutes Induction: 8-20 mcg/kg IV Maintenance: 3-5 mcg/kg IV increments q5-20min, or 0.5-1 mcg/kg/min IV Total dose: 8-40 mcg/kg IV Incremental Injection: Anesthesia 30-60 Minutes Induction: 20-50 mcg/kg IV Maintenance: 5-15 mcg/kg IV increments q5-20min Total dose: Up to 75 mcg/kg IV Anesthetic Induction: Anesthesia >45 Minutes Induction: 130-245 mcg/kg IV Maintenance: 0.5-1.5 mcg/kg/min IV or other general anesthetic Total dose: depends on duration of operation Continuous Infusion: For Anesthesia >45 Minutes Induction: 50-75 mcg/kg IV Maintenance: 0.5-3 mcg/kg/min IV Total dose: depends on duration of operation

Child Dose

Dose should be calculated based on ideal body weight Intravenous Child: <12 years Anesthesia Not recommended >12 years Incremental Injection: Anesthesia <30 Minutes Induction: 8-20 mcg/kg IV Maintenance: 3-5 mcg/kg IV increments q5-20min, or 0.5-1 mcg/kg/min IV Total dose: 8-40 mcg/kg IV Incremental Injection: Anesthesia 30-60 Minutes Induction: 20-50 mcg/kg IV Maintenance: 5-15 mcg/kg IV increments q5-20min Total dose: Up to 75 mcg/kg IV Anesthetic Induction: Anesthesia >45 Minutes Induction: 130-245 mcg/kg IV Maintenance: 0.5-1.5 mcg/kg/min IV or other general anesthetic Total dose: depends on duration of operation Continuous Infusion: For Anesthesia >45 Minutes Induction: 50-75 mcg/kg IV Maintenance: 0.5-3 mcg/kg/min IV Total dose: depends on duration of operation

Renal Dose

Administration

IV Preparation Add 20 mL to 230 mL of diluent for a final concentration of 40 mg/mL IV Administration Keep Naloxone and resuscitation equip available By incremental injection as analgesic adjunct to anesthesia with barbiturate/nitrous oxide/oxygen for short surgical procedures (expected duration <1 hr) By continuous infusion as a maintenance analgesic with nitrous oxide/oxygen for general surgical procedures By IV injection in aesthetic doses for anesthesia induction for general surgical procedures with a minimum expected duration of 45 min By IV inj as the analgesic component for monitored anesthesia care (MAC)

Contra Indications

Obstructive airway disease, resp depression. Hypersensitivity, Increased intracranial pressure. Admin in labour or before clamping of cord during caesarean section. Concomitant use during or w/in 14 days of MAOI therapy.

Precautions

Therapy exposes patients and other users to the risks of opioid addiction, abuse, and misuse, which can lead to overdose and death; assess each patient’s risk prior to prescribing therapy, and monitor all patients regularly for the development of these behaviors and conditions. Patient w/ hypovolaemia, CV disease (e.g. acute MI), bradyarrhythmias, history of drug abuse or acute alcoholism, head injury, intracranial lesions, increased intracranial pressure, pulmonary disease, decreased resp reserve, compromised respiration, COPD or other obstructive pulmonary disease, kyphoscoliosis or other skeletal disorder, and compromised intracerebral compliance, hypothyroidism. Hepatic and renal impairment. Elderly and debilitated patients. Childn. Pregnancy and lactation. Patient Counselling This drug may cause impaired cognitive function, if affected, do not drive or operate machinery. Monitoring Parameters Continuously monitor vital signs, oxygen saturation, BP, and heart rate. Monitor the patient well after surgery for delayed effects.

Pregnancy-Lactation

Pregnancy Prolonged use of opioid analgesics during pregnancy may cause neonatal opioid withdrawal syndrome; available data in pregnant women are insufficient to inform a drug-associated risk for major birth defects and miscarriage Labor or delivery Opioids cross placenta and may produce respiratory depression and psycho-physiologic effects in neonates; an opioid antagonist, such as naloxone, must be available for reversal of opioid induced respiratory depression in neonate; drug is not recommended for use in women during and immediately prior to labor, when use of shorter-acting analgesics or other analgesic techniques are more appropriate; opioid analgesics can prolong labor through actions that temporarily reduce strength, duration, and frequency of uterine contractions; however, this effect is not consistent and may be offset by an increased rate of cervical dilatation, which tends to shorten labor; monitor neonates exposed to opioid analgesics during labor for signs of excess sedation and respiratory depression Lactation The developmental and health benefits of breastfeeding should be considered along with mother’s clinical need for therapy; capsules and any potential adverse effects on breastfed infant from therapy or from underlying maternal condition Monitor infants exposed to drug through breast milk for excess sedation and respiratory depression; withdrawal symptoms can occur in breastfed infants when maternal administration of an opioid analgesic is stopped, or when breast- feeding is stopped Withdrawal signs can occur in breast-fed infants when maternal administration of an opioid analgesic is stopped or when breastfeeding is stopped; naloxone may precipitate opioid withdrawal in a breast-fed infant whose mother received opioid analgesics Lactation: use with caution

Interactions

Increased risk of prolonged/delayed resp depression w/ CYP3A4 isoenzyme inhibitors (e.g. ketoconazole, itraconazole, fluconazole, voriconazole, ritonavir, erythromycin, diltiazem, cimetidine). Enhanced resp depressant effect w/ barbiturates, benzodiazepines, neuroleptics, halogenic gases, and non-selective CNS depressants (e.g. alcohol). May increase blood concentration of propofol by 17%. May predispose to bradycardia or hypotension w/ drugs that depress the heart or increase vagal tone (e.g. β-blockers, anaesth agents). May cause bradycardia and cardiac arrest w/ non-vagolytic muscle relaxants. Potentially Fatal: Rarely, may cause severe and unpredictable potentiation of MAOIs.

Adverse Effects

Side effects of Alfentanil : >10% Arrhythmia (14%) Bradycardia (14%) Chest wall rigidity (17%) Hypertension (18%) Nausea (28%) Vomiting (18%) Tachycardia (12%) 1-10% Apnea (3-9%) Blurred vision (1-3%) Dizziness (3-9%) Hypotension (10%) Post-op respiratory depression (1-3%) Skeletal muscle movements (3-9%) Postoperative sedation (1-3%) <1% Sweating, flushing Warmness of the face/neck/upper thorax Pruritus Urticaria Respiratory (undefined) Respiratory/circulatory depression Respiratory arrest Shock Cardiac arrest Nervous System (undefined) Dizziness Visual disturbances Mental clouding/depression Sedation Coma Euphoria Dysphoria Weakness Faintness Agitation Restlessness Nervousness Seizures

Mechanism of Action

Alfentanil is a short-acting opioid analgesic related to fentanyl. It binds w/ stereospecific receptors w/in the CNS, thereby altering pain perception, increasing pain threshold, and inhibiting ascending pain pathways.