promethazine and codeine (cont.)
There may be an increase in the risk of certain neurologic reactions that
affect movement of muscles (EPS, see below) when promethazine is combined with
medicines that also cause EPS. Such drugs include antipsychotics, metoclopramide
(Reglan), and amoxapine (Asendin).
Promethazine should not be used with propylthiouracil (PTU) due to the
increased risk of low white blood cell counts and increased risk of infections.
The reason for this interaction is not known.
Concurrent use of promethazine with the dye used for myelography (X-rays of
the spinal cord) can lower the threshold for
seizures and thus increase the risk
of seizures. Promethazine should be stopped at least 48 hours before myelography
and not restarted until at least 24 hours after myelography.
PREGNANCY: There are no adequate studies of promethazine and codeine in
pregnant women. Administration of promethazine within two weeks of delivery may
affect platelet function in the newborn. Codeine generally is avoided
during
pregnancy because it may cause fetal physical dependence, withdrawal and growth
retardation.
NURSING MOTHERS: It is not known if promethazine is excreted in
breast milk.
Small amounts of codeine are secreted in breast milk, but the risk of adverse
events in the infant is small.
SIDE EFFECTS: Promethazine often causes sedation. In children less than
two
years of age, it can depress respiration and lead to death. Therefore, it should
not be used in children less than two years old. Dizziness also may occur.
Ironically, promethazine sometimes stimulates activity in patients, particularly
children. Such stimulation may be manifest by restlessness,
inability to sleep,
palpitations (rapid heartbeat) or even seizures. Promethazine also causes
anticholinergic side effects such as blurred vision, dry mouth, dilated pupils,
nausea, urinary retention (inability to urinate),
impotence, and constipation.
EPS may occur. EPS are categorized as dystonic reactions (alterations in
muscle tone), sharp, involuntary muscle movements often limited to one muscle or
muscle group, akathisia (subjective restlessness), and Parkinsonism.
Parkinsonian symptoms are more common in older persons whereas children more
often develop involuntary muscle movement reactions. Dystonic reactions are most
commonly seen during the first week of treatment. Restlessness and Parkinsonian
symptoms usually develop days to weeks after starting therapy.
A complex called neuroleptic malignant syndrome (NMS) can occur in patients
receiving phenothiazines. NMS consists of high body temperature, severe EPS,
changes in consciousness and mental status, and increased heart rate with low or
high blood pressure. NMS occurs more frequently in young men and in
persons who
are dehydrated.
Rarely, blood cell disorders can occur; low white cell counts can lead to
severe infections.
Phenothiazines such as promethazine can cause skin hyperpigmentation
(darkening) but usually only after prolonged use. The effect usually is
restricted to areas of the body exposed to sunlight. Thus, people who need
long-term treatment with promethazine should either keep out of the sun or use
effective sunscreens.
Phenothiazines can cause blurred vision, difficulty with nighttime vision, or
changes in color vision.
Liver damage has been reported rarely with phenothiazines. Jaundice is
possible. Jaundice also may occur in newborns of mothers who receive
phenothiazines during pregnancy.
Phenothiazines such as promethazine block dopamine receptors. This effect can
lead to increases in blood levels of prolactin, a hormone involved in lactation
(formation of breast milk). As a result, phenothiazines can cause the breast to
produce fluid ("milk") even when a woman is not pregnant. Additionally,
phenothiazines can cause missed menstrual periods, breast enlargement or
tenderness, loss of sexual drive, impotence, inability to ejaculate, and
priapism (prolonged penile erection). Weight gain also may occur.
The most frequent side effects of codeine include lightheadedness,
dizziness, nausea, vomiting, shortness of breath, and sedation. Other side
effects include allergic reactions, constipation, abdominal pain, rash, and
itching. Codeine is habit forming. Mental and physical dependence can occur but
are unlikely when used for short-term pain relief. If codeine is suddenly
withdrawn after prolonged use, symptoms of withdrawal may develop. The dose of
codeine should be reduced gradually in order to avoid withdrawal symptoms.
Reference: FDA Prescribing Information
Last Editorial Review: 10/13/2009
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