Prostacin

Uses

Prostacin Hydrochloride is used for the treatment of the signs and symptoms of Benign Prostatic Hyperplasia (BPH).

Prostacin is also used to associated treatment for these conditions: Benign Prostatic Hyperplasia (BPH), Benign Prostatic Hypertrophy, Bladder Outlet Obstruction, Ureteral Calculus

How Prostacin works

Prostacin is a blocker of alpha-1A and alpha-1D adrenoceptors. About 70% of the alpha-1 adrenoceptors in the prostate are of the alpha-1A subtype. By blocking these adrenoceptors, smooth muscle in the prostate is relaxed and urinary flow is improved. The blocking of alpha-1D adrenoceptors relaxes the detrusor muscles of the bladder which prevents storage symptoms. The specificity of tamsulosin focuses the effects to the target area while minimizing effects in other areas.

Dosage

Prostacin dosage

The recommended dose of Prostacinis 0.4 mg once daily. It should be administered approximately half/hour following the same meal each day. For those patients who fail to respond to the 0.4 mg dose after two to four weeks of dosing, the dose of Prostacin can be increased to 0.8mg once daily. If Prostacin administration is discontinued or interrupted for several days at either the 0.4 mg or 0.8 mg dose, therapy should be started again with the 0.4 mg once daily dose.

Side Effects

The following adverse reactions have been reported during the use of Prostacin: dizziness, abnormal ejaculation, and less frequently (1-2%) headache, asthenia, postural hypotension, palpitations, and rhinitis.

Gastrointestinal reactions such as nausea, vomiting, diarrhoea, and constipation can occasionally occur. Hypersensitivity reactions such as rash, pruritus, and urticaria can occur occasionally. As with other alpha-blockers, drowsiness, blurred vision, dry mouth, or edema can occur. Syncope has been reported rarely, and there have been very rare reports of angioedema and priapism.

Toxicity

In the event of overdose, patients may experience hypotension and should lie down in a supine position to maintain blood pressure and heart rate. If further measures are required intravenous fluids should be considered. If further progression is required, vasopressors may be used and renal function should be monitored. Dialysis is unlikely to assist in treating overdose because tamsulosin is extensively protein bound.

The oral LD50 in rats is 650mg/kg.

Prostacin is not indicated for use in women and no studies have been performed in pregnancy, though animal studies have not shown fetal harm. Prostacin is excreted in the milk of rats but there is no available data on what the effect of this tamsulosin exposure may be. Animal studies have shown male and female rat fertility is affected by tamsulosin due to impairment of ejaculation and fertilization. In men, tamsulosin is associated with abnormal ejaculation. Prostacin is not mutagenic but may be carcinogenic at levels above the maximum recommended human dose. Female rats experience a slight increase in the rates of mammary gland fibroadenomas and adenocarcinomas.

Precaution

Not indicated for use in women. Severe renal impairment (CrCl <10 mL/min). Pregnancy and lactation.

Interaction

Increased plasma concentration with strong CYP3A4 inhibitors (e.g. ketoconazole). Moderate CYP3A4 inhibitors (e.g. erythromycin), strong (e.g. paroxetine) or moderate (e.g. terbinafine) CYP2D6 inhibitors may increase exposure of tamsulosin. Increased plasma concentration with cimetidine. Additive effect with other α-adrenergic blocking agents. Concomitant use with PDE5 inhibitors may lead to symptomatic hypotension. Decreased plasma concentration with furosemide.

Food Interaction

• Take after a meal. Take 30 minutes after the same meal each day to reduce plasma level variations.

[Moderate] ADJUST DOSING INTERVAL: Food may delay the gastrointestinal absorption of tamsulosin.

The time to maximum plasma concentration (Tmax) is reached by 4 to 5 hours under fasted conditions and by 6 to 7 hours when tamsulosin is administered with food.

The delay in Tmax has the desirable effect of smoothing the tamsulosin plasma concentration profile, thereby reducing fluctuation of the plasma peak and trough concentrations with multiple dosing.

Food may also affect the extent of absorption of tamsulosin.

It has been reported that taking tamsulosin under fasted conditions results in a 30% increase in bioavailability (AUC) and 40% to 70% increase in peak plasma concentration (Cmax) compared to fed conditions.

The effects of food on the pharmacokinetics of tamsulosin are consistent regardless of whether tamsulosin is taken with a light meal or a high-fat meal.

MANAGEMENT: To ensure uniformity of absorption, tamsulosin should be administered approximately one-half hour following the same meal each day.

Prostacin Alcohol interaction

[Moderate] GENERALLY AVOID:

The concurrent use of ethanol and alpha-1 adrenergic blockers may cause increased hypotensive effects.

Patients with aldehyde dehydrogenase deficiencies (primarily Asians) may be at a higher risk of this interaction.

The mechanism has not been determined.

Data exist for prazosin and other alpha adrenergic blockers are expected to interact also.

In addition, any patients taking alpha adrenergic blockers may experience excessive orthostatic hypotension with ethanol ingestion, due to ethanol's unopposed vasodilatory effects in the presence of alpha adrenergic blockade.

Patients who develop

a flushing reaction after ethanol ingestion (indicates a possible aldehyde dehydrogenase deficiency) should be advised to avoid ethanol or limit their intake.

All patients should be warned about the possibility of orthostatic hypotension with concurrent ethanol use.

Prostacin Drug Interaction

Minor: tadalafil, furosemideUnknown: aspirin, aspirin, ubiquinone, rosuvastatin, apixaban, omega-3 polyunsaturated fatty acids, atorvastatin, pregabalin, metoprolol, metoprolol, polyethylene glycol 3350, clopidogrel, budesonide / formoterol, acetaminophen, cyanocobalamin, ascorbic acid, cholecalciferol, rivaroxaban

Prostacin Disease Interaction

Major: glaucomaModerate: hypotension, end-stage renal disease, severe liver disease

Volume of Distribution

16L after intravenous administration.

Elimination Route

Oral tamsulosin is 90% absorbed in fasted patients. The area under the curve is 151-199ng/mL*hr for a 0.4mg oral dose and 440-557ng/mL*hr for a 0.8mg oral dose. The maximum plasma concentration is 3.1-5.3ng/mL for a 0.4mg oral dose and 2.5-3.6ng/mL for a 0.8mg oral dose. Taking tamsulosin with food increases the time to maximum concentration from 4-5 hours to 6-7 hours but increases bioavailability by 30% and maximum plasma concentration by 40-70%.

Half Life

The half life in fasted patients is 14.9±3.9 hours. The elimination half life is 5-7 hours and the apparent half life is 9 to 13 hours in healthy subjects. In patients who require tamsulosin, the apparent half life is 14-15 hours.

Clearance

2.88L/h.

Elimination Route

97% of an orally administered does is recovered in studies, which 76% in the urine and 21% in the feces after 168 hours. 8.7% of the dose is excreted as unmetabolized tamsulosin.

Pregnancy & Breastfeeding use

Prostacin Hydrochloride capsules are not indicated for use in women.

Contraindication

History of orthostatic hypotension. Severe hepatic impairment.

Special Warning

Prostacin Hydrochloride capsules are not indicated for use in pediatric populations.

Acute Overdose

As overdose of Prostacin Hydrochloride capsules lead to hypotension, support the cardiovascular system is of first importance. Restoration of blood pressure and normalization of heart rate may be accomplished by keeping the patient in supine position. If this measure is inadequate, then administration of intravenous fuid should be considered. Measures, such as emesis, can be taken to impede absorption. When large quantities are involved, gastric lavage can be applied and activated charcoal and an osmotic laxative, such as sodium sulphate, can be administered.

Storage Condition

Store between 20-25° C.

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