TERAZOSIN Drug Interactions: What You Need to Know

Drug Interactions In controlled trials, terazosin has been added to diuretics, and several beta-adrenergic blockers; no unexpected interactions were observed. Terazosin has also been used in patients on a variety of concomitant therapies; while these were not formal interaction studies, no interactions were observed. Terazosin has been used concomitantly in at least 50 patients on the following drugs or drug classes: 1) analgesic/anti-inflammatory (e.g., acetaminophen, aspirin, codeine, ibuprofen, indomethacin). 2) antibiotics (e.g., erythromycin, trimethoprim and sulfamethoxazole). 3) anticholinergic/sympathomimetics (e.g., phenylephrine hydrochloride, phenylpropanolamine hydrochloride, pseudoephedrine hydrochloride). 4) antigout (e.g., allopurinol). 5) antihistamines (e.g., chlorpheniramine). 6) cardiovascular agents (e.g., atenolol, hydrochlorothiazide, methyclothiazide, propranolol). 7) corticosteroids. 8) gastrointestinal agents (e.g., antacids). 9) hypoglycemics. 10) sedatives and tranquilizers (e.g., diazepam). Use with Other Drugs In a study (n = 24) where terazosin and verapamil were administered concomitantly, terazosin's mean AUC 0-24 increased 11% after the first verapamil dose and after 3 weeks of verapamil treatment it increased by 24% with associated increases in C max (25%) and C min (32%) means. Terazosin mean T max decreased from 1.3 hours to 0.8 hours after 3 weeks of verapamil treatment. Statistically significant differences were not found in the verapamil level with and without terazosin. In a study (n = 6) where terazosin and captopril were administered concomitantly, plasma disposition of captopril was not influenced by concomitant administration of terazosin and terazosin maximum plasma concentrations increased linearly with dose at steady-state after administration of terazosin plus captopril (see DOSAGE AND ADMINISTRATION ). Carcinogenesis, Mutagenesis, Impairment of Fertility Terazosin was devoid of mutagenic potential when evaluated in vivo and in vitro (the Ames test, in vivo cytogenetics, the dominant lethal test in mice, in vivo Chinese hamster chromosome aberration test and V79 forward mutation assay). Terazosin, administered in the feed to rats at doses of 8 mg/kg/day, 40 mg/kg/day, and 250 mg/kg/day (70 mg/m 2 /day, 350 mg/m 2 /day, and 2,100 mg/m 2 /day), for two years, was associated with a statistically significant increase in benign adrenal medullary tumors of male rats exposed to the 250 mg/kg dose. This dose is 175 times the maximum recommended human dose of 20 mg (12 mg/m 2 ). Female rats were unaffected. Terazosin was not oncogenic in mice when administered in feed for 2 years at a maximum tolerated dose of 32 mg/kg/day (110 mg/m 2 ; 9 times the maximum recommended human dose). The absence of mutagenicity in a battery of tests, of tumorigenicity of any cell type in the mouse carcinogenicity assay, of increased total tumor incidence in either species, and of proliferative adrenal lesions in female rats, suggests a male rat species-specific event. Numerous other diverse pharmaceutical and chemical compounds have also been associated with benign adrenal medullary tumors in male rats without supporting evidence for carcinogenicity in man. The effect of terazosin on fertility was assessed in a standard fertility/reproductive performance study in which male and female rats were administered oral doses of 8 mg/kg/day, 30 mg/kg/day and 120 mg/kg/day. Four of 20 male rats given 30 mg/kg (240 mg/m 2 ; 20 times the maximum recommended human dose) and five of 19 male rats given 120 mg/kg (960 mg/m 2 ; 80 times the maximum recommended human dose) failed to sire a litter. Testicular weights and morphology were unaffected by treatment. Vaginal smears at 30 mg/kg/day and 120 mg/kg/day, however, appeared to contain less sperm than smears from control matings and good correlation was reported between sperm count and subsequent pregnancy. Oral administration of terazosin for one or two years elicited a statistically significant increase in the incidence of testicular atrophy in rats exposed to 40 mg/kg/day and 250 mg/kg/day (29 times and 175 times the maximum recommended human dose), but not in rats exposed to 8 mg/kg/day (> 6 times the maximum recommended human dose). Testicular atrophy was also observed in dogs dosed with 300 mg/kg/day (> 500 times the maximum recommended human dose) for three months but not after one year when dosed with 20 mg/kg/day (38 times the maximum recommended human dose). This lesion has also been seen with prazosin hydrochloride, another (marketed) selective-alpha-1 blocking agent.

TEZRULY is contraindicated in patients known to be hypersensitive to terazosin or any component of TEZRULY. Hypersensitivity to terazosin hydrochloride or any other ingredient in TEZRULY. (4)

AND PRECAUTIONS Syncope and “First-dose” Effect: Advise patients about the possibility of symptoms related to postural hypotension and to avoid situations where injury could result should syncope occur, especially when starting TEZRULY. (5.1)

Orthostatic

Hypotension: Dizziness, lightheadedness, and palpitations can occur with use of TEZRULY. Advise patients to take their first dose of TEZRULY at bedtime and to avoid driving or hazardous tasks for 12 hours after the first dose, after a dosage increase, and after interruption of therapy when treatment is resumed. (5.2) Risk of Hypotension with Concomitant Use of Other Antihypertensive Agents and Phospodiesterase Type 5 Inhibitors (PDE5-I): Concomitant administration of TEZRULY with antihypertensives or phosphodiesterase-5 (PDE-5) inhibitors can result in additive blood pressure lowering effects and symptomatic hypotension (5.3). Priapism: Advise patients about the possibility and seriousness of priapism. (5.4)

Intraoperative Floppy Iris

Syndrome: Advise patients considering cataract surgery to tell their ophthalmologist that they have taken terazosin as Intraoperative Floppy Iris Syndrome as been observed during cataract surgery in some patients. (5.5)

Prostatic

Cancer: Screen for the presence of prostatic cancer prior to treatment for BPH and at regular intervals afterwards. (5.6)

5.1 Syncope and ‘‘First-dose’’ Effect TEZRULY, like other alpha-1-adrenoceptors antagonists, can cause marked lowering of blood pressure, especially postural hypotension, and syncope in association with the first dose or first few days of therapy <span class="opacity-50 text-xs">[see Warnings and Precautions (5.2)]</span> . A similar effect can be anticipated if therapy is interrupted for several days and then restarted. Syncope has also been reported with other alpha-1-adrenoceptors antagonists in association with rapid dosage increases or the introduction of another antihypertensive drug. Syncope is believed to be due to an excessive postural hypotensive effect, although occasionally the syncopal episode has been preceded by a bout of severe supraventricular tachycardia with heart rates of 120-160 beats per minute. Additionally, the possibility of the contribution of hemodilution to the symptoms of postural hypotension should be considered. To decrease the likelihood of syncope or excessive hypotension, initiate treatment with a 1 mg dose of terazosin, given at bedtime. Higher doses (e.g., 2 to 10 mg) are not indicated as initial therapy. Then slowly increase the dose <span class="opacity-50 text-xs">[see Dosage and Administration (2.1 and 2.2)]</span> , and add additional antihypertensive agents with caution. Advise patients to avoid situations, such as driving or hazardous tasks, where injury could result should syncope occur during initiation of therapy. In early investigational studies, where increasing single doses up to 7.5 mg were given at 3-day intervals, tolerance to the first dose phenomenon did not necessarily develop and the ‘‘first-dose” effect could be observed at all doses. Syncopal episodes occurred in 3 of the 14 subjects given terazosin at doses of 2.5, 5 and 7.5 mg, which are higher than the recommended initial dose; in addition, severe orthostatic hypotension (blood pressure falling to 50/0 mmHg) was seen in two others and dizziness, tachycardia, and lightheadedness occurred in most subjects. These adverse effects all occurred within 90 minutes of dosing. In three placebo-controlled BPH studies 1, 2, and 3 <span class="opacity-50 text-xs">[see Clinical Pharmacology (1 2 )]</span> , the incidence of postural hypotension in the terazosin treated patients was 5.1%, 5.2%, and 3.7% respectively. In multiple dose clinical trials involving nearly 2000 hypertensive patients treated with terazosin, syncope was reported in about 1% of patients. Syncope was not necessarily associated only with the first dose. If syncope occurs, place the patient in a recumbent position and treat supportively as necessary. There is evidence that the orthostatic effect of terazosin is greater, even in chronic use, shortly after dosing. The risk of the events is greatest during the initial seven days of treatment but continues at all time intervals.

5.2 Orthostatic Hypotension While syncope is the most severe orthostatic effect of terazosin, other symptoms of lowered blood pressure <span class="opacity-50 text-xs">[see Warnings and Precautions (5.1)]</span> , such as dizziness, lightheadedness and palpitations were more common and occurred in some 28% of patients in clinical trials of hypertension. In BPH clinical trials, 21% of the patients experienced one or more of the following: dizziness, hypotension, postural hypotension, syncope, and vertigo. Patients with occupations in which such events represent potential problems should be treated with particular caution. Advise patients to take their first dose of TEZRULY at bedtime and to avoid driving or hazardous tasks for 12 hours after the first dose, after a dosage increase, and after interruption of therapy when treatment is resumed.

5.3 Risk of Hypotension with Concomitant Use of Other Antihypertensive Agents and Phosphodiesterase Type 5 Inhibitors (PDE5-I) Concomitant use of TEZRULY with other anti-hypertensive agents, especially the calcium channel blocker verapamil, can increase the risk of hypotension. To reduce the risk of hypotension, dosage reduction and re-titration of either agent may be necessary <span class="opacity-50 text-xs">[see Warnings and Precautions (5.1 and 5.2)]</span> . Hypotension has been reported when terazosin has been used with phosphodiesterase-5 (PDE-5) inhibitors. Therefore, PDE-5 inhibitor therapy should be initiated at the lowest dose in patients taking TEZRULY.

5.4 Priapism Rarely (probably less than once in every several thousand patients) terazosin and other alpha-1-selective adrenoceptor antagonist have been associated with priapism (painful penile erection, sustained for hours and unrelieved by sexual intercourse or masturbation). Because this condition can lead to permanent impotence if not promptly treated, advise patients about the seriousness of the condition and the need to seek immediate medical attention at an emergency room.

5.5 Prostatic Cancer Carcinoma of the prostate and BPH present with many of the same symptoms and frequently co-exist. Therefore, examine patients thought to have BPH prior to starting TEZRULY therapy to rule out the presence of carcinoma of the prostate.

5.6 Intraoperative Floppy Iris Syndrome Intraoperative floppy iris syndrome (IFIS) has been observed during cataract surgery in some patients on/or previously treated with alpha-1-adrenoceptor antagonists. 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 ophthalmologist should be prepared for possible implementation of intraoperative preventive measures and modifications to surgical techniques during phacoemulsification surgery to reduce overall complication rates. There does not appear to be a benefit of stopping alpha-1-adrenoceptor antagonists therapy prior to cataract surgery.

5.7 Laboratory Tests Small but statistically significant decreases in hematocrit, hemoglobin, white blood cells, total protein and albumin were observed in controlled clinical trials. These laboratory findings suggested the possibility of hemodilution. Treatment with terazosin for up to 24 months had no significant effect on prostate specific antigen (PSA) levels.