8 USE IN SPECIFIC POPULATIONS
Prolonged use of opioid analgesics during pregnancy may cause neonatal opioid withdrawal syndrome. Available data with alfentanil injection in pregnant women are insufficient to inform a drug-associated risk for major birth defects and miscarriage.
In animal reproduction studies, alfentanil reduced pup birth weights and increased pup mortality when administered to pregnant rats during gestation and throughout lactation at 9 times the human dose of 335 mcg/kg per procedure. Alfentanil was embryocidal when administered to pregnant rabbits during organogenesis at 72.6 times the human dose of 335 mcg/kg per procedure. No malformations were noted in rats or rabbits treated with alfentanil during organogenesis [see Data]. The estimated background risk of major birth defects and miscarriage for the indicated population is unknown. All pregnancies have a background risk of birth defect, loss, or other adverse outcomes. In the U.S. general population, the estimated background risk of major birth defects and miscarriage in clinically recognized pregnancies is 2% to 4% and 15% to 20%, respectively.
Fetal/Neonatal Adverse Reactions
Prolonged use of opioid analgesics during pregnancy for medical or nonmedical purposes can result in physical dependence in the neonate and neonatal opioid withdrawal syndrome shortly after birth.
Neonatal opioid withdrawal syndrome presents as irritability, hyperactivity and abnormal sleep pattern, high pitched cry, tremor, vomiting, diarrhea and failure to gain weight. The onset, duration, and severity of neonatal opioid withdrawal syndrome vary based on the specific opioid used, duration of use, timing and amount of last maternal use, and rate of elimination of the drug by the newborn. Observe newborns for symptoms of neonatal opioid withdrawal syndrome and manage accordingly [see Warnings and Precautions (5.3)].
Labor or Delivery
Opioids cross the 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 the neonate. Alfentanil injection is not recommended for use in pregnant women during or immediately prior to labor, when other analgesic techniques are more appropriate. Opioid analgesics, including alfentanil injection, can prolong labor through actions which temporarily reduce the strength, duration, and frequency of uterine contractions. However, this effect is not consistent and may be offset by an increased rate of cervical dilation, which tends to shorten labor. Monitor neonates exposed to opioid analgesics during labor for signs of excess sedation and respiratory depression.
Pregnant rats were treated with intravenous alfentanil doses of 0.08, 0.31, or 1.25 mg/kg/day (2.3, 9, or 36.6 times the human total dose of 335 mcg/kg based on body surface area, respectively). No malformations or embryotoxic effects were noted despite maternal toxicity (increased mortality in the mid- and high-dose group).
Pregnant rabbits were treated with intravenous alfentanil doses of 0.08, 0.31, or 1.25 mg/kg/day (4.6, 18, or 72.6 times the human total dose of 335 mcg/kg based on body surface area, respectively). Decreased live fetuses per litter and decreased litter size in the high dose group were noted in the presence of maternal toxicity (decreased body weight gain and mortality in the high-dose group).
No evidence of malformations or adverse effects on the fetus was reported in a published study in which pregnant rats were administered 8 mg/kg/day alfentanil (232 times the human dose of 335 mcg/kg/day based on body surface area) continuously from Gestation Day 5 through Gestation Day 20 via subcutaneously implanted osmotic minipumps.
Pregnant rats were treated intravenously with alfentanil 0.08, 0.31, or 1.25 mg/kg/day (2.3, 9, or 36.6 times the human total dose of 335 mcg/day based on body surface area, respectively) during gestation and throughout lactation. Reduced birth weights and decreased pup survival were noted in the mid- and high-dose groups in the presence of maternal toxicity (increased mortality in the mid- and high-dose groups).
The developmental and health benefits of breastfeeding should be considered along with the mother's clinical need for alfentanil injection and any potential adverse effects on the breastfed infant from alfentanil injection or from the underlying maternal condition.
Infants exposed to alfentanil injection through breast milk should be monitored 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.
8.3 Females and Males of Reproductive Potential
Chronic use of opioids may cause reduced fertility in females and males of reproductive potential. It is not known whether these effects on fertility are reversible [see Adverse Reactions (6.2)].
8.4 Pediatric Use
Adequate data to support the use of alfentanil injection in children under the age of 12 years of age are not presently available.
8.5 Geriatric Use
In one clinical trial, the dose of alfentanil required to produce anesthesia, as determined by appearance of delta waves in EEG, was 40% lower in geriatric patients than that needed in healthy young patients.
The initial dose of alfentanil injection should be appropriately reduced in elderly. Patients over the age of 65 have been found to have reduced plasma clearance and extended terminal elimination which may prolong postoperative recovery.
Elderly patients (aged 65 years or older) may have increased sensitivity to alfentanil. In general, use caution when selecting a dosage for an elderly patient, usually starting at the low end of the dosing range, reflecting the greater frequency of decreased hepatic, renal, or cardiac function and of concomitant disease or other drug therapy.
Respiratory depression is the chief risk for elderly patients treated with opioids, and has occurred after large initial doses were administered to patients who were not opioid-tolerant or when opioids were co-administered with other agents that depress respiration. Titrate the dosage of alfentanil injection slowly in geriatric patients [see Warnings and Precautions (5.6)].
This drug is known to be substantially excreted by the kidney, and the risk of adverse reactions to this drug may be greater in patients with impaired renal function. Because elderly patients are more likely to have decreased renal function, care should be taken in dose selection, and it may be useful to monitor renal function.
8.6 Hepatic Impairment
Alfentanil injection should be administered with caution patients with liver dysfunction because of the extensive hepatic metabolism. Reduce the dosage as needed and monitor closely for signs of respiratory depression, sedation, and hypotension.
8.7 Renal Impairment
Alfentanil injection should be administered with caution to patients with kidney dysfunction because of the renal excretion of alfentanil and its metabolites. Reduce the dosage as needed and monitor for signs of respiratory depression, sedation, and hypotension.
8.8 Respiratory Impairment
Alfentanil injection should be used with caution in patients with pulmonary disease, decreased respiratory reserve, or potentially compromised respiration, in such patients opioids may additionally decrease respiratory drive and increase airway resistance. During anesthesia, this can be managed by assisted or controlled respiration.