PRECAUTIONS
General
TYLENOL® with Codeine (acetaminophen and codeine phosphate) tablets should
be prescribed with caution in certain special-risk patients, such as the elderly
or debilitated, and those with severe impairment of renal or hepatic function,
head injuries, elevated intracranial pressure, acute abdominal conditions, hypothyroidism,
urethral stricture, Addison's disease, or prostatic hypertrophy.
Ultra-Rapid Metabolizers of Codeine
Some individuals may be ultra-rapid metabolizers due to a specific CYP2D6*2x2
genotype. These individuals convert codeine into its active metabolite, morphine,
more rapidly and completely than other people. This rapid conversion results
in higher than expected serum morphine levels. Even at labeled dosage regimens,
individuals who are ultra-rapid metabolizers may experience overdose symptoms
such as extreme sleepiness, confusion, or shallow breathing.
The prevalence of this CYP2D6 phenotype varies widely and has been estimated
at 0.5 to 1% in Chinese and Japanese, 0.5 to 1% in Hispanics, 1 to 10% in Caucasians,
3% in African Americans, and 16 to 28% in North Africans, Ethiopians, and Arabs.
Data is not available for other ethnic groups.
When physicians prescribe codeine-containing drugs, they should choose the
lowest effective dose for the shortest period of time and inform their patients
about these risks and the signs of morphine overdose (see PRECAUTIONS – Nursing
Mothers).
Laboratory Tests
In patients with severe hepatic or renal disease, effects of therapy should
be monitored with serial liver and/or renal function tests.
Carcinogenesis, Mutagenesis, Impairment of Fertility
No adequate studies have been conducted in animals to determine whether acetaminophen
and codeine have a potential for carcinogenesis or mutagenesis. No adequate
studies have been conducted in animals to determine whether acetaminophen has
a potential for impairment of fertility. Acetaminophen and codeine have been
found to have no mutagenic potential using the Ames Salmonella-Microsomal Activation
test, the Basc test on Drosophila germ cells, and the Micronucleus test on mouse
bone marrow.
Pregnancy
Teratogenic Effects: Pregnancy Category C.
Codeine
A study in rats and rabbits reported no teratogenic effect of codeine administered
during the period of organogenesis in doses ranging from 5 to 120 mg/kg. In
the rat, doses at the 120 mg/kg level, in the toxic range for the adult animal,
were associated with an increase in embryo resorption at the time of implantation.
In another study a single 100 mg/kg dose of codeine administered to pregnant
mice reportedly resulted in delayed ossification in the offspring.
There are no adequate and well-controlled studies in pregnant women. TYLENOL®
with Codeine (acetaminophen and codeine phosphate) tablets should be used during
pregnancy only if the potential benefit justifies the potential risk to the
fetus.
Nonteratogenic Effects
Dependence has been reported in newborns whose mothers took opiates regularly
during pregnancy. Withdrawal signs include irritability, excessive crying, tremors,
hyperreflexia, fever, vomiting, and diarrhea. These signs usually appear during
the first few days of life.
Labor and Delivery
Narcotic analgesics cross the placental barrier. The closer to delivery and
the larger the dose used, the greater the possibility of respiratory depression
in the newborn. Narcotic analgesics should be avoided during labor if delivery
of a premature infant is anticipated. If the mother has received narcotic analgesics
during labor, newborn infants should be observed closely for signs of respiratory
depression. Resuscitation may be required (see OVERDOSAGE).
The effect of codeine, if any, on the later growth, development, and functional
maturation of the child is unknown.
Nursing Mothers
Acetaminophen is excreted in breast milk in small amounts, but the significance
of its effect on nursing infants is not known. Because of the potential for
serious adverse reactions in nursing infants from acetaminophen, a decision
should be made whether to discontinue the drug, taking into account the importance
of the drug to the mother.
Codeine is secreted into human milk. In women with normal codeine metabolism
(normal CYP2D6 activity), the amount of codeine secreted into human milk is
low and dose-dependent. Despite the common use of codeine products to manage
postpartum pain, reports of adverse events in infants are rare. However, some
women are ultra-rapid metabolizers of codeine. These women achieve higher-than-expected
serum levels of codeine's active metabolite, morphine, leading to higher-than-expected
levels of morphine in breast milk and potentially dangerously high serum morphine
levels in their breastfed infants. Therefore, maternal use of codeine can potentially
lead to serious adverse reactions, including death, in nursing infants.
The prevalence of this CYP2D6 phenotype varies widely and has been estimated
at 0.5 to 1% in Chinese and Japanese, 0.5 to 1% in Hispanics, 1 to 10% in Caucasians,
3% in African Americans, and 16 to 28% in North Africans, Ethiopians, and Arabs.
Data is not available for other ethnic groups.
The risk of infant exposure to codeine and morphine through breast milk should
be weighed against the benefits of breastfeeding for both the mother and baby.
Caution should be exercised when codeine is administered to a nursing woman.
If a codeine containing product is selected, the lowest dose should be prescribed
for the shortest period of time to achieve the desired clinical effect. Mothers
using codeine should be informed about when to seek immediate medical care and
how to identify the signs and symptoms of neonatal toxicity, such as drowsiness
or sedation, difficulty breastfeeding, breathing difficulties, and decreased
tone, in their baby. Nursing mothers who are ultra-rapid metabolizers may also
experience overdose symptoms such as extreme sleepiness, confusion, or shallow
breathing. Prescribers should closely monitor mother-infant pairs and notify
treating pediatricians about the use of codeine during breastfeeding (see PRECAUTIONS
– General, Ultra-Rapid Metabolizers of Codeine).