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Posts Tagged ‘Tamsulosin’

Benign Prostatic Hyperplasia

Posted by admin on July 11th, 2011 No Comments

Definition Benign prostatic hyperplasia, a nearly ubiquitous condition, is the most common benign neoplasm of American men and occurs as a result of hormone-driven prostate growth. Pathophysiology The prostate gland comprises three types of tissue: epithelial or glandular, stromal or smooth muscle, and capsule. Both stromal tissue and capsule are embedded with О±1-adrenergic receptors. The precise pathophysiologic mechanisms that cause Benign prostatic hyperplasia are not clear. However, both intraprostatic dihydrotestosterone and type II 5 О±-reductase are thought to be involved. Benign prostatic hyperplasia commonly results from both static (gradual enlargement of the prostate) and dynamic (agents or situations that increase О±-adrenergic tone and constrict the gland's smooth muscle) factors. Examples of drugs that can exacerbate symptoms include testosterone, О±-adrenergic agonists (e.g., decongestants), anticholinergics (e.g., antihistamines, phenothiazines, tricyclic antidepressants, anticholinergic antispasmodics, Read more [...]

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Options for Treatment of Benign Prostatic Hyperplasia: Alpha-Blockers

Posted by admin on June 21st, 2011 No Comments

Benign prostatic hyperplasia is one of the most common benign tumors affecting men over 40 years of age. The mean age at which patients develop symptoms is between 60 to 65 years. Ninety percent of men in their eighties exhibit histologic evidence of disease, 81% will experience symptoms due to benign prostatic hyperplasia, and 10% will develop acute urinary retention. The aging of the population also increases the number of men at risk for benign prostatic hyperplasia. In the past year, more than 1.7 million men have made an office visit to the urologist and these numbers continue to increase. In the last 10 years, there has been a major shift in both the physician's and patient's perception of benign prostatic hyperplasia. From being considered a disease of aging, requiring intervention only to prevent potential complications, an emphasis shift has occurred. Today, benign prostatic hyperplasia is considered more a disease that affects quality of life; therefore, both evaluations and treatments are currently designed to relieve symptoms and reduce side effects. In this context, the use of medical Read more [...]

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Pharmacophysiologic Rationale for the use of Alpha-Blocker Drugs

Posted by admin on June 21st, 2011 No Comments

The prostate gland is often referred to as being composed of five distinct lobes during fetal development — anterior, posterior, median, and two lateral lobes. In the adult prostate, this distinction is usually abolished and the prostate is considered to be composed of three concentric layers: the outer layer (the external prostate gland proper) and the two inner layers (the periurethral glands). Prostate cancer tends to arise in the outer layers of the glands while benign prostatic hyperplasia starts in the inner periurethral glands. Benign prostatic hyperplasia is believed to arise from fibrostromal proliferation in the periurethral glands. As the gland progresses in size, patients will present with lateral and/or median prostatic lobe(s) enlargement. This latter will result in (a) compression, narrowing, and elongation of the prostatic urethra; (b) growth of the median lobe into the bladder, causing a ball-valve effect and possibly an increase in irritative symptoms; (c) a bladder response to obstruction that may result initially in hypertrophy and subsequently in decompensation, stasis Read more [...]

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Alpha-1A Subtype Selective Alpha-Adrenergic Antagonist

Posted by admin on June 21st, 2011 No Comments

Tamsulosin Tamsulosin is a newly developed member of this class of drugs, is suitable for once-a-day dosing schedule, and is currently being studied extensively in the treatment of benign prostatic hyperplasia. Tamsulosin is a (-)-S-[2-[[2-(o-ethoxyphenoxy) ethylamino] propyl]-2-methoxybenzenesulfonamide HC1, a sulphamoylphenethylamine derivative which possesses potent and selective alpha-1A receptor antagonism. In preclinical trials, tamsulosin has been shown to have 13 times more efficacy for prostatic smooth muscle as compared to urethral smooth muscles. Other studies have revealed a 10 to 12 times higher affinity for prostatic receptors as opposed to vascular and extraprostatic tissue. Recent changes in nomenclature of alpha-blockers reveal the alpha-1A receptors to predominate in the prostate while alpha-IB and alpha-ID receptors predominate in the vascular smooth muscle. Tamsulosin belongs to a class of alpha-lA-receptor antagonists that have preferred selectivity for prostatic smooth muscle although it does have some binding to vascular smooth muscle receptors as well. Tamsulosin binding Read more [...]

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Cardiovascular Effects

Posted by admin on June 21st, 2011 No Comments

By blocking the alpha-1 adrenoceptor, these drugs cause peripheral vasodilation, which reduces total peripheral vascular resistance and thereby lowers high blood pressure. Indeed, reduction in blood pressure was the primary indication for which alpha-1 adrenoceptor antagonists were developed. The effects of selective alpha-1 blockade on the blood pressure of patients with benign prostatic hyperplasia are important in terms of the risk of adverse effects related to hypotension, both in normotensive patients and in those treated with other anti-hypertensives. Given that both benign prostatic hyperplasia and hypertension become more prevalent with increasing age, and that one would expect to find that a large proportion of older men have both conditions, these are very real concerns. Clinicians are often faced with the dilemma of what to do when treating a patient with benign prostatic hyperplasia who already has hypertension controlled by an agent other than alpha-blockers. Should the existing antihypertensive agent be withdrawn or the alpha-blockers be given in addition to existing medication? Read more [...]

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Pharmacologic Strategies for Prevention

Posted by admin on June 21st, 2011 No Comments

Alpha-Blockers Alpha-adrenergic blockers have been shown to rapidly alleviate symptoms and improve urinary flow rates in men with lower urinary tract symptoms but do not appear to alter the disease process in such a way as to prevent progression. Alpha-blockers may induce apoptosis in the prostate gland but longitudinal data do not show a measurable effect on prostate volume. Alpha-blockers have not been typically studied in long-term controlled trials, and there are therefore only limited data available on long-term effects on outcomes. Only two controlled studies longer than 3 months have reported on outcomes such as acute urinary retention or benign prostatic hyperplasia-related surgery; only one of these, the 1-year placebo-controlled HYCAT study, had a predefined objective of evaluating resource utilization although the high proportion of patients who discontinued the study (42%) and had no follow-up information limits interpretation. In HYCAT, no significant difference was found in the number of patients who underwent prostatectomy during the 1-year trial (48 in the placebo and 41 in the Read more [...]

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Alpha Blockers

Posted by admin on May 10th, 2011 No Comments

Overview Hyperplasia of the stromal tissue may or may not lead to significant enlargement of the prostate, but it usually leads to dynamic benign prostatic hyperplasia by increasing prostatic smooth muscle, which triggers increased smooth-muscle tension and resistance to urine flow. (The dynamic and static components of benign prostatic hyperplasia are discussed in the "Etiology and Pathophysiology" section.) Alpha1-adrenergic receptors in the bladder neck and prostatic capsule mediate tension in these muscles. Although the alpha1-adrenergic antagonists, or alpha blockers, currently used to block these receptors (e.g., doxazosin [Pfizer/AstraZeneca's Cardura/Cardura XL, generics] and terazosin [Abbott's Hytrin, generics]) reduce benign prostatic hyperplasia symptoms and resistance to urine flow, some of them also cause cardiovascular side effects. The latest entrants in this field (e.g., tamsulosin [Astel-las/Boehringer Ingelheim/Abbott's Harnal/Flomax/Omnic, others] and alfuzosin [Sanofi-Aventis's Xatral/Xatral SR/Uroxatral, others]) are prostate-specific or uroselective alpha blockers that reduce Read more [...]

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Silodosin

Posted by admin on May 10th, 2011 No Comments

Among the drugs in the pipeline for benign prostatic hyperplasia, silodosin (Figure 10), also known as KMD-3213, is in the most advanced stage of development. The agent is being codeveloped by Kissei and Daiichi in Japan. In June 2004, a new drug application (NDA) was submitted to the Pharmaceuticals and Medical Devices Agency (PMDA), and in 2004, Daiichi announced an expected launch date of 2006 in Japan. In April 2004, Kissei entered a licensing agreement with Watson Pharmaceuticals, which will develop and market silodosin in Mexico, Canada, and the United States, where Phase III clinical trials were in progress in 2005. In December 2004, Kissei granted Recordati exclusive rights to the development of silodosin in 45 countries in Europe. Silodosin is a highly selective, twice-daily oral alpha blocker that preferentially inhibits the activity of alpha1A-adrenergic receptors, which are predominantly located in the prostate. Other alpha blockers that are considered uroselective, such as tamsulosin, block not only alphai A-adrenoceptors but also other adrenergic receptor subtypes found in Read more [...]

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Gonadotropin Modulators

Posted by admin on May 10th, 2011 No Comments

Overview Gonadotropin modulators, also known as steroid androgen antagonists (e.g., chlormadinone acetate [Teikoku's Prostal/Prostal L]), are specifically labeled for treating benign prostatic hyperplasia, and their use is especially high in Japan, where finasteride and dutasteride are not approved. Potentially serious side effects (e.g., diarrhea, sexual dysfunction, liver toxicity) make agents in this class less desirable than less-toxic therapies such as the 5-ARIs. Because these agents are marketed primarily for prostate cancer, they are not discussed in detail here, with the exception of chlormadinone, which is often prescribed in Japan. Mechanism Of Action The control of androgen production in the testes is directly mediated by hypothalamic/pituitary hormones. Gonadotropin-releasing hormone, also known as luteinizing hormone-releasing hormone, is secreted by neurons in the hypothalamus, and it subsequently stimulates the release of both luteinizing hormone and follicle-stimulating hormone in the anterior pituitary. In the testes, luteinizing hormone interacts with specific cell-surface Read more [...]

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Benign Prostatic Hyperplasia: Alpha Blockers

Posted by admin on May 10th, 2011 No Comments

Overview Numerous alpha blockers have been approved for the treatment of benign prostatic hyperplasia in the major pharmaceutical markets (United States, France, Germany, Italy, Spain, United Kingdom, and Japan), largely replacing the need for surgical treatment in the past ten years. Alpha blockers, with tamsulosin as the leading agent, currently constitute the largest segment of the benign prostatic hyperplasia drug market. Alpha-blocker drugs may differ in terms of their relative inhibitory potency and specificity for alpha1-adrenergic receptors, but most seem to exhibit the same degree of efficacy in benign prostatic hyperplasia patients . However, the propensity for inducing side effects, such as orthostatic hypotension and retrograde ejaculation, often distinguishes one alpha blocker from another. Nevertheless, alpha-blocker activity is sustained over several years of therapy, thereby eliminating the need for dose increases that could increase side effects. Mechanism Of Action Alpha blockers inhibit the activity of adrenergic receptors (also known as adrenoceptors), which cause smooth-muscle Read more [...]

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