HI-Alfa SR 10

Indications

• Benign prostatic hyperplasia (BPH)

Dosage

Children: null

Adults: Initially, 10 mg once daily after a meal. Dose adjustments may be necessary based on individual response and tolerability.

Mechanism of action

Alfuzosin selectively binds to and inhibits alpha(1)-adrenergic receptors located in the prostate, bladder base, bladder neck, prostatic capsule, and prostatic urethra. This blockade leads to the relaxation of smooth muscle in these areas, resulting in improved urinary flow and alleviation of symptoms associated with benign prostatic hyperplasia (BPH).

Pharmacodynamics

By selectively inhibiting alpha adrenergic receptors in the lower urinary tract, alfuzosin induces smooth muscle relaxation in the bladder neck and prostate, which enhances urine flow and reduces BPH symptoms. Additionally, it diminishes the vasoconstrictor effects of catecholamines like epinephrine and norepinephrine, causing peripheral vasodilation. This can increase the risk of postural hypotension or syncope, necessitating caution in patients on concurrent antihypertensives or nitrates.

Pharmacokinetics

Alfuzosin is well-absorbed following oral administration and has a bioavailability of approximately 50%. It undergoes extensive hepatic metabolism, primarily via cytochrome P450 enzymes, leading to various metabolites. The elimination half-life is around 5 to 7 hours, and it is excreted mainly in the urine. Renal impairment may affect alfuzosin clearance, thus requiring careful monitoring of renal function in patients.

Adverse effects

• dizziness
• headache
• fatigue
• postural hypotension
• syncope
• gastrointestinal disturbances

Interactions

• ribociclib+alfuzosin: Severe (increases exposure)
• cobicistat+alfuzosin: Moderate (increases exposure)
• idelalisib+alfuzosin: Moderate (increases exposure)

Precautions

• Caution in patients taking nitrates or antihypertensives due to risk of postural hypotension.
• Monitor blood pressure regularly, especially after initiating treatment.

Pregnancy

Alfuzosin should be used during pregnancy only if the potential benefit justifies the potential risk to the fetus, as safety in pregnancy has not been established.

Breast-feeding

It is not known whether alfuzosin is excreted in human milk. Caution is advised when administering to nursing mothers.

Storage

Store at room temperature, away from moisture and heat. Keep out of reach of children.

Formulations

• Alfuzosin hydrochloride 10 mg extended-release tablets

Indications

• Benign prostatic hyperplasia
• Lower urinary tract symptoms related to BPH
• Acute urinary retention associated with benign prostatic hyperplasia

Dosage

Adults: For immediate-release preparations, the initial dose is 2.5 mg twice daily, adjusted according to response, with a maximum of 10 mg per day. For elderly patients, the initial dose is 2.5 mg twice daily, also adjustable according to response. For modified-release preparations, the recommended dosage is 10 mg once daily.

Mechanism of action

Alfuzosin hydrochloride selectively blocks alpha-1 adrenergic receptors in the smooth muscle of the prostate and bladder neck, leading to muscle relaxation. This reduces urinary outflow obstruction and alleviates symptoms of BPH.

Pharmacodynamics

The drug exerts its effects by inhibiting the alpha-1 adrenergic receptors, which results in the relaxation of smooth muscles in the bladder neck and prostate. This action improves urinary flow and decreases symptoms such as urinary hesitancy and urgency. The onset of action typically occurs within a few hours, with peak effects observed in about 1 to 3 hours after dosing.

Pharmacokinetics

Alfuzosin is well absorbed after oral administration but undergoes first-pass metabolism in the liver. The bioavailability of the immediate-release formulation ranges from 30% to 50%. The drug is primarily metabolized by the liver, with an elimination half-life of approximately 5 to 7 hours. The majority of the drug is excreted as metabolites in the urine, with minimal unchanged drug present.

Contra-indications

• History of micturition syncope
• History of postural hypotension

Adverse effects

• Asthenia
• Diarrhoea
• Dizziness
• Dry mouth
• Headache
• Malaise
• Nausea
• Postural hypotension

Interactions

• Concomitant use of antihypertensives may require dosage adjustment and supervision
• Alpha1-selective adrenoceptor blockers may increase the risk of symptomatic orthostatic hypotension

Precautions

• Acute heart failure
• Cerebrovascular disease
• Intra-operative floppy iris syndrome in cataract surgery
• Elderly patients may require careful monitoring due to the risk of falls

Pregnancy

Alfuzosin hydrochloride should be used in pregnancy only if the potential benefit justifies the potential risk to the fetus.

Breast-feeding

It is not known whether alfuzosin is excreted in human milk. Caution should be exercised when administering to breastfeeding women.

Storage

Store at room temperature, away from moisture and heat. Keep out of reach of children.

Formulations

• Immediate-release tablets 2.5 mg
• Immediate-release tablets 10 mg
• Modified-release tablets 10 mg

Mechanism of action

Alpha(1)-adrenoreceptors are found in the prostate, bladder base, bladder neck, prostatic capsule, and prostatic urethra; their activation may lead to contraction of smooth muscle and urinary symptoms in patients with BPH. Alfuzosin selectively binds to and inhibits alpha(1)-adrenergic receptors in the lower urinary tract. This leads to the relaxation of smooth muscle in both the prostate and bladder neck, resulting in the improvement in urine flow and a reduction of urinary symptoms. Alfuzosin hydrochloride, a quinazoline-derivative alpha1-adrenergic blocking agent, is structurally and pharmacologically related to prazosin. Alfuzosin is a non-subtype-specific alpha1-adrenergic blocking agent that exhibits selectivity for alpha1-adrenergic receptors in the lower urinary tract (e.g., bladder base, bladder neck, prostate, prostatic capsule, prostatic urethra). Blockade of these adrenoreceptors can cause relaxation of smooth muscle in the bladder neck and prostate, resulting in improvement in urine flow and a reduction in symptoms of benign prostatic hyperplasia (BPH).

Pharmacodynamics

By selectively inhibiting alpha adrenergic receptors in the lower urinary tract, alfuzosin causes smooth muscle relaxation in the bladder neck and prostate, improving urine flow, thereby reducing BPH symptoms. Additionally, alfuzosin reduces the vasoconstrictor effect of catecholamines (epinephrine and norepinephrine), leading to peripheral vasodilation. This leads to a risk of postural hypotension/syncope, and prescribing information warns that caution should be exercised in patients who take nitrates, antihypertensives, or have experienced decreased blood pressure after using other medications.