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Postural hypotension with or without symptoms (e.g., dizziness) may develop within a few hours following administration of CARDURA. However, infrequently, symptomatic postural hypotension has also been reported later than a few hours after dosing. As with other alpha-blockers, there is a potential for syncope, especially after the initial dose or after an increase in dosage strength. Advise patient how to avoid symptoms resulting from postural hypotension and what measures to take should they develop.
Concomitant administration of CARDURA with a PDE-5 inhibitor can result in additive blood pressure lowering effects and symptomatic hypotension.
Intraoperative Floppy Iris Syndrome (IFIS) has been observed during cataract surgery in some patients on or previously treated with alpha1 blockers. This variant of small pupil syndrome is characterized by the combination of a flaccid iris that billows in response to intraoperative irrigation currents, progressive intraoperative miosis despite preoperative dilation with standard mydriatic drugs, and potential prolapse of the iris toward the phacoemulsification incisions. The patient's surgeon should be prepared for possible modifications to their surgical technique, such as the utilization of iris hooks, iris dilator rings, or viscoelastic substances. There does not appear to be a benefit of stopping alpha1 blocker therapy prior to cataract surgery.
Carcinoma of the prostate causes many of the symptoms associated with BPH and the two disorders frequently co-exist. Carcinoma of the prostate should therefore be ruled out prior to commencing therapy with CARDURA for the treatment of BPH.
Alpha1 antagonists, including doxazosin, have been associated with priapism (painful penile erection, sustained for hours and unrelieved by sexual intercourse or masturbation). This condition can lead to permanent impotence if not promptly treated.
Patient Counseling Information
Advise the patient to read the FDA-approved patient labeling (PATIENT INFORMATION).
Advise patients of the possibility of syncopal and orthostatic symptoms, especially at the initiation of therapy, and urged to avoid driving or hazardous tasks for 24 hours after the first dose, after a dosage increase, and after interruption of therapy when treatment is resumed. Advise patients to report symptoms to their healthcare provider.
Advise patients of the possibility of priapism and to seek immediate medical attention if symptoms occur.
Carcinogenesis, Mutagenesis, Impairment Of Fertility
Carcinogenesis And Mutagenesis
Chronic dietary administration (up to 24 months) of doxazosin mesylate at maximally tolerated doses of 40 mg/kg/day in rats and 120 mg/kg/day in mice revealed no evidence of carcinogenic potential. The highest doses evaluated in the rat and mouse studies are associated with AUCs (a measure of systemic exposure) that are 8 times and 4 times, respectively, the human AUC at a dose of 16 mg/day.
Mutagenicity studies revealed no drug-or metabolite-related effects at either chromosomal or subchromosomal levels.
Fertility In Males
Studies in rats showed reduced fertility in males treated with doxazosin at oral doses of 20 (but not 5 or 10) mg/kg/day, about 4 times the AUC exposures obtained with a 12 mg/day human dose. This effect was reversible within two weeks of drug withdrawal. There have been no reports of any effects of doxazosin on male fertility in humans.
Use In Specific Populations
The limited available data with CARDURA in pregnant women are not sufficient to inform a drug-associated risk for major birth defects and miscarriage. However, untreated hypertension during pregnancy can result in increased maternal risks [see Clinical Considerations]. In animal reproduction studies, no adverse developmental effects were observed when doxazosin was orally administered to pregnant rabbits and rats during the period of organogenesis at doses of up to 41 and 20 mg/kg, respectively (exposures in rabbits and rats were 10 and 4 times, respectively, the human AUC exposures with a 12 mg/day therapeutic dose). A dosage regimen of 82 mg/kg/day in the rabbit was associated with reduced fetal survival [see Data].
The estimated background risk of major birth defects and miscarriage for the indicated population is unknown. In the U.S. general population, the estimated background risk of major birth defects and miscarriage in clinically recognized pregnancies is 2-4% and 15-20%, respectively.
Disease-associated Maternal And/Or Embryo/Fetal Risk
Hypertension in pregnancy increases the maternal risk for pre-eclampsia, gestational diabetes, premature delivery, and delivery complications (e.g., need for cesarean section, and post-partum hemorrhage). Hypertension increases the fetal risk for intrauterine growth restriction and intrauterine death.
Radioactivity was found to cross the placenta following oral administration of labelled doxazosin to pregnant rats. Studies in pregnant rabbits and rats at daily oral doses of up to 41 and 20 mg/kg, respectively (plasma drug concentrations of 10 and 4 times, respectively, the human AUC exposures with a 12 mg/day therapeutic dose), have revealed no evidence of adverse developmental effects. A dosage regimen of 82 mg/kg/day in the rabbit was associated with reduced fetal survival. In peri-and postnatal studies in rats, postnatal development at maternal doses of 40 or 50 mg/kg/day of doxazosin (about 8 times human AUC exposure with a 12 mg/day therapeutic dose) was delayed, as evidenced by slower body weight gain and slightly later appearance of anatomical features and reflexes.
There is limited information on the presence of CARDURA in human milk [see Data]. There is no information on the effects of CARDURA on the breastfeed infant or the effects on milk production.
A single case study reports that CARDURA is present in human milk, which resulted in an infant dose of less than 1% of the maternal weight-adjusted dosage and a milk/plasma ratio of 0.1. However, these data are insufficient to confirm the presence of CARDURA in human milk.
The safety and effectiveness of CARDURA have not been established in children.
Benign Prostatic Hyperplasia (BPH)
The safety and effectiveness profile of CARDURA was similar in the elderly (age ≥ 65 years) and younger (age < 65 years) patients.
Clinical studies of CARDURA did not include sufficient numbers of subjects aged 65 and over to determine whether they respond differently from younger subjects. Other reported clinical experience has not identified differences in responses between the elderly and younger patients.
In general, dose selection for an elderly patient should be cautious, 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.
CARDURA is extensively metabolized in the liver. Hepatic impairment is expected to increase exposure to doxazosin. Use of CARDURA in patients with severe hepatic impairment (Child-Pugh Class C) is not recommended. Monitor blood pressure and for symptoms of hypotension in patients with lesser degrees of hepatic impairment (Child-Pugh Class A and B) [see CLINICAL PHARMACOLOGY].This monograph has been modified to include the generic and brand name in many instances.
Last reviewed on RxList: 6/24/2016
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