Lopress

Prazosin hydrochloride.

LOPRESS TABLET (1 MG): Each tablet contains Prazosin hydrochloride equivalent to Prazosin 1 mg.
LOPRESS TABLET (2 MG): Each tablet contains Prazosin hydrochloride equivalent to Prazosin 2 mg.

Pharmacology: Pharmacodynamics: Prazosin hydrochloride is a quinazolin-derivative postsynaptic α₁ adrenergic blocking agent.
Prazosin hydrochloride causes a reduction in total peripheral resistance by dilation of vascular smooth muscle, which may be related to postsynaptic α₁ adrenergic receptors blockade.
Pharmacokinetics: Prazosin is readily absorbed from the gastrointestinal tract following oral administration and peak plasma concentration occur 1 to 3 hours after an oral dose. The oral bioavailability is variable and a range of 43% to 85% has been reported. Prazosin is highly bound to plasma proteins (92% to 97%). It is extensively metabolized in the liver and some of the metabolites are reported to have hypotensive activity. It is excreted as the metabolites and 5% to 11% as unchanged Prazosin mainly in the feces via the bile, less than 10% is excreted in the urine. It is not dialyzable. The plasma half-life of Prazosin after oral administration has been reported to be 2-4 hours.

Hypertension: Prazosin is used alone or in combination with a diuretic and/or other classes of antihypertensive agents in the management of hypertension as needed for proper patient response.
Benign prostatic hyperplasia (BPH, benign prostatic hypertrophy): Prazosin has been used in the symptomatic treatment of urinary obstruction caused by benign prostatic hypertrophy.

Recommended dose: Hypertension: The recommended starting dose is 0.5 mg taken two or three times daily for 3 to 7 days. If tolerated the dose may then be increased to 1 mg taken two or three times daily for a further 3 to 7 days, and thereafter gradually increased according to patient's response to a usual maximum dose of 20 mg daily in divided dose.
Concomitant therapy with diuretics or other antihypertensives: When diuretics or other hypotensive agents are added to existing Prazosin therapy, the dosage of Prazosin in adults should be reduced to 1 or 2 mg given 3 times daily and gradually increased according to the response and tolerance of the patient. When patients receive other antihypertensive therapy but inadequate control, the dosage of the other drug should be reduced to a maintenance level and Prazosin initiated at 0.5 mg in the evening, then continuing with 0.5 mg twice or three times daily.
Benign Prostatic Hyperplasia: The recommended starting dose is 0.5 mg twice daily, increasing to a maintenance dose not exceeding 2 mg twice daily.
Patients with moderate to severe renal impairment: It is recommended that therapy be initiated at 0.5 mg daily and that dosage increases be instituted cautiously.
Patients with hepatic impairment: It is recommended that therapy be initiated at 0.5 mg daily and that dosage increases be instituted cautiously.
Elderly: Since the elderly may be more susceptible to hypotension, therapy should be initiated with the lowest possible dose.
Pediatric precaution: It is not recommended for the treatment of children under the age of 12 years since safe conditions for its use have not been established.
Mode of Administration: Prazosin hydrochloride is administered orally.
Dosage of Prazosin must be adjusted according to the patient's blood pressure response and tolerance.

Overdose and treatment: If overdosage with Prazosin occurs activated charcoal should be given if the patient presents within 1 hour of ingestion. If overdosage of Prazosin causes hypotension, supportive therapy should be initiated. The patient should be kept in the supine position; if necessary, shock may be treated with plasma volume expanders and vasopressor drugs. Renal function should be monitored. Prazosin is not dialyzable because it is highly protein bound.

Prazosin is contraindicated in patients with known history of hypersensitivity to Prazosin, any other quinazolines derivatives (e.g., alfuzosin, doxazosin, terazosin), or any ingredient in the formulation.

A very small percentage of patients may respond in an abrupt and exaggerated manner to the initial dose of Prazosin. Postural hypotension evidenced by dizziness and weakness, or rarely loss of consciousness, has been reported, particularly with the commencement of therapy, but this effect is readily avoided by initiating treatment with a low dose of Prazosin and with small increases in dosage during the first one to two weeks of therapy.
For patients taking medications that are known to lower blood pressure, Prazosin may augment the efficacy of antihypertensive therapy.
Patients with moderate to severe grades of renal impairment, it is recommended that therapy be initiated at 0.5 mg daily and that dosage increases be instituted cautiously.
In patients with benign prostatic hyperplasia: Prazosin is not recommended for patients with a history of micturition syncope.
Effects on ability to drive and use machine: Patients who engage in potentially hazardous activities such as operating machinery or driving motor vehicles should be warned about possible drowsiness, dizziness, or lightheadedness.

Pregnancy: Pregnancy category: C.
There are no adequate and well-controlled studies to date using Prazosin in pregnant women, however the drug should be used during pregnancy only when the potential benefits justify risks to the fetus.
Lactation: Since Prazosin is distributed into milk in small amounts, the drug should be used with caution in nursing women.

The more common adverse effects include dizziness, drowsiness, orthostatic hypotension, headache, lack of energy, nausea, palpitation. These effects may diminish with continued therapy or may be relieved by a reduction in dosage.
Other adverse effects: oedema, chest pain, dyspnoea, constipation, diarrhea, vomiting, depression, nervousness, sleep disturbances, vertigo, hallucinations, paraesthesia, nasal congestion, epistaxis, dry mouth, urinary frequency and incontinence, reddened sclera, blurred vision, tinnitus, abnormal liver enzyme values, pancreatitis, arthralgia, alopecia, lichen planus, skin rashes, pruritus, and diaphoresis.
Impotence and priapism have also been reported.

Diuretics and Hypotensive Agents: When Prazosin is administrated with diuretics or other hypotensive agents, particularly β-adrenergic blocking agents (e.g., propranolol), the hypotensive effect of Prazosin may be increased. This effect is usually used to therapeutic advantage, but careful adjustment of dosage is necessary when these drugs are used concomitantly.
Phosphodiesterase Type 5 Inhibitors: Concomitant administration of Prazosin and a phosphodiesterase type 5 (PDE5) inhibitor (e.g. sildenafil, tadalafil, vardenafil) may result in additive hypotensive effects and symptomatic hypotension. Therefore, PDE5 inhibitor therapy should be initiated at lowest possible dosage in patients receiving Prazosin.
Protein-bound drug: Since Prazosin is highly bound to plasma proteins, the possibility that it may interact with other highly protein-bound drugs should be considered.

Store below 30°C, protect from light.

Other Antihypertensives

C02CA01 - prazosin ; Belongs to the class of alpha-adrenoreceptor antagonists, peripherally-acting antiadrenergic agents. Used in the treatment of hypertension.

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