Conmy

Conmy

terazosin

Manufacturer:

Taiwan Biotech

Distributor:

New Smart Formulae
Full Prescribing Info
Contents
Terazosin HCl.
Description
Each tablet contains Terazosin (as hydrochloride) 2 mg.
Terazosin hydrochloride, an alpha-1-selective adrenoceptor blocking agent is a quinazoline derivative represented by the following chemical name and structural formula (RS)-Piperazine-1-(4amino-6,7dimethoxy-2-quinazolinyl)-4-{tetra-hydro-2-furanyl}carbonyl}, monohydrochloride, dehydrate.
Action
Pharmacology: Pharmacodynamics: Benign Prostatic Hyperplasia (BPH): The symptoms associated with BPH are related to bladder outlet obstruction, which is compromised of two underlying components: a static component and a dynamic component.
Static Component is a consequence of an increase in prostate size. Over time, the prostate will continue to enlarge. However, clinical studies have demonstrated that the size of the prostate does not correlate with the severity of BPH symptoms, or the degree of urinary obstruction.
Dynamic Component is a function of an increase in smooth muscle tone in the prostate and bladder neck, leading to construction of the bladder outlet. Smooth muscle tone is mediated by sympathetic nervous stimulation of alpha-1 adrenoceptors, which are abundant in the prostate, prostatic capsule and the bladder neck. The reduction in symptoms and improvement in urine flow rates following administration of terazosin is related to relaxation of smooth muscle produced by blockade of alpha-1 adrenoceptors in the bladder neck and prostate. Because there are relatively few alpha-1 adrenoceptors in the bladder body, terazosin is able to reduce the bladder outlet obstruction without affecting bladder contractility.
Pharmacokinetics: Terazosin is rapidly and almost completely absorbed from the gastrointestinal tract after oral administration; the bioavailability is reported to be about 90%. It is metabolized in the liver; one of the metabolites is reported to possess antihypertensive activity. The half-life in plasma is approximately 12 hours. It is excreted in faeces via the bile and in the urine, as unchanged drug and metabolites. Terazosin is 90 to 94% protein bound.
Indications/Uses
Terazosin hydrochloride is indicated for the treatment of hypertension and symptomatic benign prostatic hyperplasia (BPH).
Dosage/Direction for Use
Benign Prostatic Hyperplasia: Initial dose: 1 mg at bedtime is the starting dose for all patients, and this dose should not be exceeded as an initial dose. Patients should be closely followed during initial administration in order to minimize the risk of severe hypotensive response.
Subsequent dose: the dose should be increased at intervals of 7 days stepwise fashion to 2 mg, 5 mg or 10 mg once daily to achieve the desired improvement of symptoms and/or flow rates. Doses of 10 mg once daily are generally required for the clinical response. Therefore, treatment with 10 mg for a minimum of 4-6 weeks may be required to assess whether a beneficial response has been achieved. Some patients may not achieve a clinical response despite appropriate titration. Although some additional patients responded to a 20 mg daily dose, there was an insufficient number of patients studied to draw definitive conclusions about this dose. There are insufficient date to support the use of higher doses for those patients who show inadequate or no response to 20 mg daily. If terazosin administration is discontinued for several days or longer therapy should be reinstituted using the initial regimen or as prescribed by physician.
Hypertension: Following oral administration its effects are seen within 15 minutes and may last for up to 24 hours permitting once daily dosage. To avoid the risk of collapse which may occur in some patients after the first dose the initial dose is the equivalent of 1 mg of terazosin at bedtime, increasing gradually at intervals of 7 days according to the patients response, to usual maximum of 20 mg of terazosin daily. The usual maintenance dose is 2 mg to 10 mg daily or as prescribed by a physician.
Overdosage
Should overdosage of terazosin hydrochloride lead to hypotension, support of the cardiovascular system is of first importance. Restoration of blood pressure and normalization of heart rate may be accomplished by keeping the patient in the supine position. If this measure is inadequate, shock should first be treated with volume expanders. If necessary, vasopressors should then be used and renal function should be monitored and supported as needed. Laboratory data indicate that terazosin is 90-94% protein bound; therefore, dialysis may not benefit.
Contraindications
Terazosin hydrochloride tablet are contraindicated in patients known to be hypersensitive to terazosin hydrochloride. It is not recommended for the treatment of heart failure caused by mechanical obstruction, i.e. Aortic or mitral valve stenosis, pulmonary embolism & restrictive pericardial disease.
Warnings
Syncope and "First dose" effect: Terazosin hydrochloride, like other alpha-adrenergic agents, can cause marked lowering of blood pressure, especially postural hypotension and syncope in association with the first dose or first few days of therapy. A similar effect can be anticipated if therapy is interrupted for several days and the restarted. Syncope has also been reported with other alpha-adrenergic blocking agents in association with rapid dosage increases of 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 about 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, treatment should always be initiated with a 1 mg dose of terazosin, given at bedtime. The 2 mg, 5 mg and 10 mg are not indicated as initial therapy. Dosage should then be increased slowly, according to recommendations in the DOSAGE & ADMINISTRATION and additional antihypertensive agents with caution. The patient should be cautioned to avoid situations, such driving or hazardous task, where injury could result, should syncope occur during initiation of therapy.
If syncope occurs, the patient should be placed in a recumbent position and treated 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.
Special Precautions
General: Prostatic Cancer: Carcinoma of the prostate and BPH cause many of the same symptoms. These two diseases frequently co-exist. Therefore, patients thought to have BPH should be examined prior to starting terazosin hydrochloride therapy to rule out the presence of carcinoma of the prostate.
Orthostatic Hypotension: While syncope is the most severe orthostatic effect of terazosin, other symptoms of lowered blood pressure, such as dizziness. lightheadedness and palpitations, were more common and occurred in some 28% of patients in clinical trials for 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.
Use in Pregnancy: Teratogenic Effects: Terazosin was not teratogenic in either rats or rabbits when administered oral doses up to 280 to 60 times; respectively, the maximum recommended human dose. Fetal resorptions occurred in rats with 480 mg/kg/day, approximately 280 times to maximum recommended human dose. Increased fetal resorptions, decrease fetal weight and an increased number of supernumerary ribs were observed in offspring of rabbits dosed with 60 times the maximum recommended human dose. The finding (in both species) were most likely secondary to maternal toxicity. There are no adequate and well-controlled studies in pregnant women and the safety of terazosin in pregnancy has not been established. Terazosin hydrochloride is not recommended during pregnancy unless the potential benefit justifies the potential risk to the mother and fetus.
Non-teratogenic Effects: In a peri- and post-natal development study in rats, significantly more pups died in the group dosed with 120 mg/kg/day (>75 times the maximum recommended human dose) then in the control group during the three week postpartum period.
Use in Lactation: It is not known whether terazosin is excreted in breast milk. Because many drugs are excreted in milk, caution should exercised when terazosin is administered to a nursing woman.
Use in children: Safety and effectiveness in children have not been determined.
Use In Pregnancy & Lactation
Use in Pregnancy: Teratogenic Effects: Terazosin was not teratogenic in either rats or rabbits when administered oral doses up to 280 to 60 times; respectively, the maximum recommended human dose. Fetal resorptions occurred in rats with 480 mg/kg/day, approximately 280 times to maximum recommended human dose. Increased fetal resorptions, decrease fetal weight and an increased number of supernumerary ribs were observed in offspring of rabbits dosed with 60 times the maximum recommended human dose. The finding (in both species) were most likely secondary to maternal toxicity. There are no adequate and well-controlled studies in pregnant women and the safety of terazosin in pregnancy has not been established. Terazosin hydrochloride is not recommended during pregnancy unless the potential benefit justifies the potential risk to the mother and fetus. Non-teratogenic Effects: In a peri- and post-natal development study in rats, significantly more pups died in the group dosed with 120 mg/kg/day (>75 times the maximum recommended human dose) then in the control group during the three week postpartum period.
Use in Lactation: It is not known whether terazosin is excreted in breast milk. Because many drugs are excreted in milk, caution should exercised when terazosin is administered to a nursing woman.
Adverse Reactions
If overdosage occurs the stomach should be emptied by gastric lavage. Severe hypotension may respond to placing the patient in the supine position with the feet raised. The effects of gross overdosage may be treated by infusions of volume expanders, and if necessary cautious intravenous infusion of a pressor agent. Terazosin is not removed by dialysis.
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: Analgesics/Anti-inflammatory-acetaminophen, aspirin, codeine, ibuprofen, indomethacin; Antibiotics-erythromycin; trimethoprim and sulfamethoxazole; Anticholinergic/sympathomimetics-phenylephrine hydrochloride, phenylpropanolamine hydrochloride; Antigout-allopurinol; Antihistamines-chlorpheniramine; Cardiovascular agents-atenolol, hydrochlorothiazide, methylclothiazide, propranolol Corticosteroids; Gastrointestinal-agents antacids; Hypoglycemia; Sedative and tranquilizers diazepam.
Use with other drugs: caution should be observed when terazosin hydrochloride is administered concomitantly with other antihypertensive agents, especially the calcium channel blocker verapamil to avoid the possibility of developing significant hypotension. When using terazosin hydrochloride and other antihypertensive agents concomitantly, dosage reduction and retitration of either agent may be necessary.
Storage
Store at temperature not exceeding 30°C.
ATC Classification
G04CA03 - terazosin ; Belongs to the class of alpha-adrenoreceptor antagonists. Used in the treatment of benign prostatic hypertrophy.
Presentation/Packing
Tab 2 mg x 100's.
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