Parlodel (Page 4 of 6)

Drug Interactions

The risk of using Parlodel in combination with other drugs has not been systematically evaluated, but alcohol may potentiate the side effects of Parlodel. Parlodel may interact with dopamine antagonists, butyrophenones, and certain other agents. Compounds in these categories result in a decreased efficacy of Parlodel: phenothiazines, haloperidol, metoclopramide, and pimozide. Bromocriptine is a substrate of CYP3A4. Caution should therefore be used when co-administering drugs which are strong inhibitors of this enzyme (such as azole antimycotics, HIV protease inhibitors). The concomitant use of macrolide antibiotics such as erythromycin was shown to increase the plasma levels of bromocriptine (mean AUC and Cmax values increased 3.7-fold and 4.6-fold, respectively).1 The concomitant treatment of acromegalic patients with bromocriptine and octreotide led to increased plasma levels of bromocriptine (bromocriptine AUC increased about 38%).4 Concomitant use of Parlodel with other ergot alkaloids is not recommended. Dose adjustment may be necessary in those cases where high doses of bromocriptine are being used (such as Parkinson’s disease indication).

Carcinogenesis, Mutagenesis, Impairment of Fertility

A 74-week study was conducted in mice using dietary levels of bromocriptine mesylate equivalent to oral doses of 10 and 50 mg/kg/day. A 100-week study in rats was conducted using dietary levels equivalent to oral doses of 1.7, 9.8, and 44 mg/kg/day. The highest doses tested in mice and rats were approximately 2.5 and 4.4 times, respectively, the maximum human dose administered in controlled clinical trials (100 mg/day) based on body surface area. Malignant uterine tumors, endometrial and myometrial, were found in rats as follows: 0/50 control females, 2/50 females given 1.7 mg/kg daily, 7/49 females given 9.8 mg/kg daily, and 9/50 females given 44 mg/kg daily. The occurrence of these neoplasms is probably attributable to the high estrogen/progesterone ratio which occurs in rats as a result of the prolactin-inhibiting action of bromocriptine mesylate. The endocrine mechanisms believed to be involved in the rats are not present in humans. There is no known correlation between uterine malignancies occurring in bromocriptine-treated rats and human risk. In contrast to the findings in rats, the uteri from mice killed after 74 weeks of treatment did not exhibit evidence of drug-related changes.

Bromocriptine mesylate was evaluated for mutagenic potential in the battery of tests that included Ames bacterial mutation assay, mutagenic activity in vitro on V79 Chinese hamster fibroblasts, cytogenetic analysis of Chinese hamster bone marrow cells following in vivo treatment, and an in vivo micronucleus test for mutagenic potential in mice.

No mutagenic effects were obtained in any of these tests.

Fertility and reproductive performance in female rats were not influenced adversely by treatment with bromocriptine beyond the predicted decrease in the weight of pups due to suppression of lactation. In males treated with 50 mg/kg of this drug, mating and fertility were within the normal range. Increased perinatal loss was produced in the subgroups of dams, sacrificed on day 21 postpartum (p.p.) after mating with males treated with the highest dose (50 mg/kg).

Pregnancy

Category B: Administration of 10-30 mg/kg of bromocriptine to 2 strains of rats on days 6 to 15 postcoitum (p.c.) as well as a single dose of 10 mg/kg on day 5 p.c. interfered with nidation. Three mg/kg given on days 6 to 15 were without effect on nidation, and did not produce any anomalies. In animals treated from day 8-15 p.c., i.e., after implantation, 30 mg/kg produced increased prenatal mortality in the form of increased incidence of embryonic resorption. One anomaly, aplasia of spinal vertebrae and ribs, was found in the group of 262 fetuses derived from the dams treated with 30 mg/kg bromocriptine. No fetotoxic effects were found in offspring of dams treated during the peri- or postnatal period.

Two studies were conducted in rabbits (2 strains) to determine the potential to interfere with nidation. Dose levels of 100 or 300 mg/kg/day from day 1 to day 6 p.c. did not adversely affect nidation. The high dose was approximately 63 times the maximum human dose administered in controlled clinical trials (100 mg/day), based on body surface area. In New Zealand white rabbits, some embryo mortality occurred at 300 mg/kg which was a reflection of overt maternal toxicity. Three studies were conducted in 2 strains of rabbits to determine the teratological potential of bromocriptine at dose levels of 3, 10, 30, 100, and 300 mg/kg given from day 6 to day 18 p.c. In 2 studies with the Yellow-silver strain, cleft palate was found in 3 and 2 fetuses at maternally toxic doses of 100 and 300 mg/kg, respectively. One control fetus also exhibited this anomaly. In the third study conducted with New Zealand white rabbits using an identical protocol, no cleft palates were produced.

No teratological or embryotoxic effects of bromocriptine were produced in any of 6 offspring from 6 monkeys at a dose level of 2 mg/kg.

Information concerning 1276 pregnancies in women taking Parlodel has been collected. In the majority of cases, Parlodel was discontinued within 8 weeks into pregnancy (mean 28.7 days), however, 8 patients received the drug continuously throughout pregnancy. The mean daily dose for all patients was 5.8 mg (range 1-40 mg).

Of these 1276 pregnancies, there were 1088 full-term deliveries (4 stillborn), 145 spontaneous abortions (11.4%), and 28 induced abortions (2.2%). Moreover, 12 extrauterine gravidities and 3 hydatidiform moles (twice in the same patient) caused early termination of pregnancy. These data compare favorably with the abortion rate (11% — 25%) cited for pregnancies induced by clomiphene citrate, menopausal gonadotropin, and chorionic gonadotropin.

Although spontaneous abortions often go unreported, especially prior to 20 weeks of gestation, their frequency has been estimated to be 15%.

The incidence of birth defects in the population at large ranges from 2% — 4.5%. The incidence in 1109 live births from patients receiving bromocriptine is 3.3%.

There is no suggestion that Parlodel contributed to the type or incidence of birth defects in this group of infants.

Nursing Mothers

Parlodel should not be used during lactation in postpartum women.

Pediatric Use

The safety and effectiveness of bromocriptine for the treatment of prolactin-secreting pituitary adenomas have been established in patients age 16 to adult. No data are available for bromocriptine use in pediatric patients under the age of 8 years. A single 8-year-old patient treated with bromocriptine for a prolactin-secreting pituitary macroadenoma has been reported without therapeutic response.

The use of bromocriptine for the treatment of prolactin-secreting adenomas in pediatric patients in the age group 11 to under 16 years is supported by evidence from well-controlled trials in adults, with additional data in a limited number (n=14) of children and adolescents 11 to 15 years of age with prolactin-secreting pituitary macro- and microadenomas who have been treated with bromocriptine. Of the 14 reported patients, 9 had successful outcomes, 3 partial responses, and 2 failed to respond to bromocriptine treatment. Chronic hypopituitarism complicated macroadenoma treatment in 5 of the responders, both in patients receiving bromocriptine alone and in those who received bromocriptine in combination with surgical treatment and/or pituitary irradiation.

Safety and effectiveness of bromocriptine in pediatric patients have not been established for any other indication listed in the INDICATIONS AND USAGE section.

Geriatric Use

Clinical studies for Parlodel did not include sufficient numbers of subjects aged 65 and over to determine whether the elderly respond differently from younger subjects. However, other reported clinical experiences, including postmarketing reporting of adverse events, have not identified differences in response or tolerability between elderly and younger patients. Even though no variation in efficacy or adverse reaction profile in geriatric patients taking Parlodel has been observed, greater sensitivity of some elderly individuals cannot be categorically ruled out. In general, dose selection for an elderly patient should be cautious, starting at the lower end of the dose range, reflecting the greater frequency of decreased hepatic, renal or cardiac function, and of concomitant disease or other drug therapy in this population.

Adverse Reactions to Parlodel

Adverse Reactions from Clinical Trials

Hyperprolactinemic Indications

The incidence of adverse effects is quite high (69%) but these are generally mild to moderate in degree. Therapy was discontinued in approximately 5% of patients because of adverse effects. These in decreasing order of frequency are: nausea (49%), headache (19%), dizziness (17%), fatigue (7%), lightheadedness (5%), vomiting (5%), abdominal cramps (4%), nasal congestion (3%), constipation (3%), diarrhea (3%) and drowsiness (3%).

A slight hypotensive effect may accompany Parlodel (bromocriptine mesylate) treatment. The occurrence of adverse reactions may be lessened by temporarily reducing dosage to ½ SnapTabs tablet 2 or 3 times daily. A few cases of cerebrospinal fluid rhinorrhea have been reported in patients receiving Parlodel for treatment of large prolactinomas. This has occurred rarely, usually only in patients who have received previous transsphenoidal surgery, pituitary radiation, or both, and who were receiving Parlodel for tumor recurrence. It may also occur in previously untreated patients whose tumor extends into the sphenoid sinus.

Acromegaly

The most frequent adverse reactions encountered in acromegalic patients treated with Parlodel were: nausea (18%), constipation (14%), postural/orthostatic hypotension (6%), anorexia (4%), dry mouth/nasal stuffiness (4%), indigestion/dyspepsia (4%), digital vasospasm (3%), drowsiness/tiredness (3%) and vomiting (2%).

Less frequent adverse reactions (less than 2%) were: gastrointestinal bleeding, dizziness, exacerbation of Raynaud’s syndrome, headache and syncope. Rarely (less than 1%) hair loss, alcohol potentiation, faintness, lightheadedness, arrhythmia, ventricular tachycardia, decreased sleep requirement, visual hallucinations, lassitude, shortness of breath, bradycardia, vertigo, paresthesia, sluggishness, vasovagal attack, delusional psychosis, paranoia, insomnia, heavy headedness, reduced tolerance to cold, tingling of ears, facial pallor and muscle cramps have been reported.

Parkinson’s Disease

In clinical trials in which Parlodel was administered with concomitant reduction in the dose of levodopa/carbidopa, the most common newly appearing adverse reactions were: nausea, abnormal involuntary movements, hallucinations, confusion, “on-off’’ phenomenon, dizziness, drowsiness, faintness/fainting, vomiting, asthenia, abdominal discomfort, visual disturbance, ataxia, insomnia, depression, hypotension, shortness of breath, constipation, and vertigo.

Less common adverse reactions which may be encountered include: anorexia, anxiety, blepharospasm, dry mouth, dysphagia, edema of the feet and ankles, erythromelalgia, epileptiform seizure, fatigue, headache, lethargy, mottling of skin, nasal stuffiness, nervousness, nightmares, paresthesia, skin rash, urinary frequency, urinary incontinence, urinary retention, and rarely, signs and symptoms of ergotism such as tingling of fingers, cold feet, numbness, muscle cramps of feet and legs or exacerbation of Raynaud’s syndrome.

Abnormalities in laboratory tests may include elevations in blood urea nitrogen, SGOT, SGPT, GGPT, CPK, alkaline phosphatase and uric acid, which are usually transient and not of clinical significance.

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