Long-acting α1-adrenergic receptor inhibitors, such as doxazosin (UK 33274), are frequently used to treat symptoms of lower urinary tract and benign prostatic hyperplasia [1]. Doxazosin may directly suppress the synthesis of cholesterol without the need of LDL receptors. Doxazosin can suppress the synthesis of cholesterol, but cells may counteract this by upregulating LDL receptors. This would increase the import of lipoprotein cholesterol and decrease the amount of LDL cholesterol in the culture medium [2]. In 8 out of 12 patients (66.7%), doxazosin monotherapy was efficacious; in 11 out of 12 patients (91.7%), combination therapy with a beta-blocker was beneficial. Throughout the course of treatment, the average pulse rate did not change. Only three subjects experienced minor and temporary adverse effects. When taking doxazosin, urinary and plasma catecholamine levels usually drop or stay the same [3].

Absorption, Distribution and Excretion
Doxazosin is rapidly absorbed in the gastrointestinal tract and peak concentrations are achieved within 2-3 hours after administration. The bioavailability is about 60%-70%. The intake of food with doxazosin is not expected to cause clinically significant effects.
In a pharmacokinetic study using a 1 mg IV radiolabeled dose and a 2 mg oral dose, 63% of the ingested doxazosin was found to be excreted in the feces and about 9% of the dose was found to be excreted in the urine. Traces of radiolabeled unchanged drug were found in the urine and about 5% of the administered drug was found as unchanged drug excreted in the feces.
The volume of distribution of doxazosin is 1.0-1.9 L/kg. In a study of radiolabeled doxazosin administered to pregnant rats, doxazosin was found to cross the placenta.
The clearance of doxazosin is low and ranges from approximately 1-2 ml/min/kg.

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Metabolism / Metabolites
Hepatic metabolism of doxazosin produces inactive O-demethylated and C-hydroxylated metabolites. Metabolism occurs via O-demethylation of the quinazoline nucleus of doxazosin or via hydroxylation of its benzodioxan portion. The enzymes involved in the metabolism of doxazosin include CYP2C19, CYP2D6, CYP2C19, and CYP3A4, which is the primary metabolizing enzyme. Doxazosin itself is considered to be mainly responsible for its pharmacological action, however, some active metabolites have been identified whose pharmacokinetics have not been adequately characterized.

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Biological Half-Life
The terminal elimination half-life of doxazosin has been estimated at 9-12 hours according to some resources. The FDA label indicates the elimination half-life of doxazosin is 22 hours.

Hepatotoxicity
Doxazosin has been associated with a low rate of serum aminotransferase elevations that in controlled trials was no higher than with placebo therapy. These elevations were transient and did not require dose modification. No instances of clinically apparent acute liver injury due to doxazosin have been published in the literature, but reports of cholestatic hepatitis have been received by the sponsor. Among the alpha adrenergic receptor antagonists, the most frequently implicated agent in causing liver injury has been alfuzosin with only single, and not well documented cases linked to other alpha blockers. Thus, acute symptomatic liver injury due to doxazosin is quite rare, and severe hepatotoxicity must be exceeding rare, if it occurs at all.
Likelihood score: E* (unproven but suspected rare cause of clinically apparent liver injury).

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Effects During Pregnancy and Lactation
◉ Summary of Use during Lactation
Limited information indicates that maternal doses of 4 mg daily produce low very levels in milk and would not be expected to cause any adverse effects in breastfed infants.
◉ Effects in Breastfed Infants
Relevant published information was not found as of the revision date.
◉ Effects on Lactation and Breastmilk
Relevant published information in nursing mothers was not found as of the revision date. However, the pharmacologically similar drug prazosin does not affect serum prolactin concentration in patients with hypertension, indicating that doxazosin may not affect prolactin levels. The prolactin level in a mother with established lactation may not affect her ability to breastfeed.

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Protein Binding
The plasma protein binding of doxazosin is estimated at 98%.. It has also been shown to be bound to the alpha-1 acid glycoprotein.

[1]. Stereoselective binding of doxazosin enantiomers to plasma proteins from rats, dogs and humans in vitro. Acta Pharmacol Sin, 2013. 34(12): p. 1568-74.

[2]. D'Eletto, R.D. and N.B. Javitt, Effect of doxazosin on cholesterol synthesis in cell culture. J Cardiovasc Pharmacol, 1989. 13 Suppl 2: p. S1-4; discussion S4.

[3]. Miura, Y. and K. Yoshinaga, Doxazosin: a newly developed, selective alpha 1-inhibitor in the management of patients with pheochromocytoma. Am Heart J, 1988. 116(6 Pt 2): p. 1785-9.

Doxazosin is a member of the class of quinazolines that is quinazoline substituted by an amino group at position 4, methoxy groups at positions 6 and 7 and a piperazin-1-yl group at position 2 which in turn is substituted by a 2,3-dihydro-1,4-benzodioxin-2-ylcarbonyl group at position 4. An antihypertensive agent, it is used in the treatment of high blood pressure. It has a role as an antihypertensive agent, an alpha-adrenergic antagonist, an antineoplastic agent, a vasodilator agent and an antihyperplasia drug. It is a member of quinazolines, a N-acylpiperazine, a N-arylpiperazine, a benzodioxine, a monocarboxylic acid amide and an aromatic amine.
Doxazosin is an alpha-1 antagonist used for the treatment of benign prostatic hypertrophy (BPH) symptoms and hypertension. Other members of this drug class include [Prazosin], [Terazosin], [Tamsulosin], and [Alfuzosin]. Because of its long-lasting effects, doxazosin can be administered once a day. It is marketed by Pfizer and was initially approved by the FDA in 1990.
Doxazosin is an alpha-Adrenergic Blocker. The mechanism of action of doxazosin is as an Adrenergic alpha-Antagonist.
Doxazosin is a nonselective alpha-1 adrenergic antagonist (alpha-blocker) used in the therapy of hypertension and benign prostatic hypertrophy. Doxazosin is associated with a low rate of transient serum aminotransferase elevations, but has not been linked to instances of clinically apparent acute liver injury.
Doxazosin is a quinazoline with antihypertensive and antineoplastic properties. Doxazosin is an alpha-adrenergic antagonist that selectively inhibits alpha-1 adrenergic receptors. Blockages of the alpha-1 adrenergic action on the vascular smooth muscles lead to a decrease in vascular resistance and antihypertensive activity. This agent also shows high affinity to alpha-1c adrenoceptor, the predominant functional type in the prostate, which may partially attribute to its effect in treatment of benign prostatic hyperplasia. Furthermore, doxazosin induces apoptosis in prostate cancer cells mediated through inhibition of protein kinase B (PKB)/Akt-signaling death receptor regulatory pathway.
A prazosin-related compound that is a selective alpha-1-adrenergic blocker.
See also: Doxazosin Mesylate (has salt form).

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Drug Indication
Doxazosin is indicated to treat the symptoms of benign prostatic hypertrophy, which may include urinary frequency, urgency, and nocturia, among other symptoms. In addition, doxazosin is indicated alone or in combination with various antihypertensive agents for the management of hypertension. Off-label uses of doxazosin include the treatment of pediatric hypertension and the treatment of ureteric calculi.

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Mechanism of Action
Doxazosin selectively inhibits the postsynaptic alpha-1 receptors on vascular smooth muscle by nonselectively blocking the alpha-1a, alpha-1b, and alpha-1d subtypes. This action on blood vessels decreases systemic peripheral vascular resistance, reducing blood pressure, exerting minimal effects on the heart rate due to its receptor selectivity. Norepinephrine-activated alpha-1 receptors located on the prostate gland and bladder neck normally cause contraction of regional muscular tissue, obstructing urinary flow and contributing to the symptoms of benign prostatic hypertrophy. Alpha-1 antagonism causes smooth muscle relaxation in the prostate and bladder, effectively relieving urinary frequency, urgency, weak urinary stream, and other unpleasant effects of BPH. Recently, doxazosin was found to cause apoptosis of hERG potassium channels in an in vitro setting, possibly contributing to a risk of heart failure with doxazosin use.

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Pharmacodynamics
Doxazosin decreases standing and supine blood pressure and relieves the symptoms of benign prostatic hypertrophy through the inhibition of alpha-1 receptors. Doxazosin may cause hypotension due to its pharmacological actions. This frequently occurs in the upright position, leading to a feeling of dizziness or lightheadedness. The first dose of doxazosin may lead to such effects, however, subsequent doses may also cause them. The risk of these effects is particularly high when dose adjustments occur or there are long intervals between doxazosin doses. Treatment should be started with the 1 mg dose of doxazosin, followed by slow titration to the appropriate dose. Patients must be advised of this risk and to avoid situations in which syncope and dizziness could be hazardous following the ingestion of doxazosin. Interestingly doxazosin exerts beneficial effects on plasma lipids. It reduces LDL (low-density lipoprotein) cholesterol and triglyceride levels and increases HDL (high-density lipoprotein) cholesterol levels. A note on priapism risk In rare cases, doxazosin and other alpha-1 blockers may cause priapism, a painful occurrence of persistent and unrelievable penile erection that can lead to impotence if medical attention is not sought as soon as possible. Patients must be advised of the priapism risk associated with doxazosin and to seek medical attention immediately if it is suspected.

C23H25N5O5

451.48

451.185

C, 61.19; H, 5.58; N, 15.51; O, 17.72

74191-85-8

Doxazosin mesylate;77883-43-3;Doxazosin-d8 hydrochloride;1219803-95-8;Doxazosin-d8;1126848-44-9

3157

Typically exists as solid at room temperature

1.371 g/cm3

718ºC at 760 mmHg

289-290°C

388ºC

2.886

1

9

4

33

678

0

O=C(N1CCN(C2=NC(N)=C3C=C(OC)C(OC)=CC3=N2)CC1)C4OC5=CC=CC=C5OC4

RUZYUOTYCVRMRZ-UHFFFAOYSA-N

InChI=1S/C23H25N5O5/c1-30-18-11-14-15(12-19(18)31-2)25-23(26-21(14)24)28-9-7-27(8-10-28)22(29)20-13-32-16-5-3-4-6-17(16)33-20/h3-6,11-12,20H,7-10,13H2,1-2H3,(H2,24,25,26)

[4-(4-amino-6,7-dimethoxyquinazolin-2-yl)piperazin-1-yl]-(2,3-dihydro-1,4-benzodioxin-3-yl)methanone

UK-33274 mesylateUK33274 mesylateUK 33274 mesylateCardura DoxazosinumDoxazosin Doxazosina Doxazosine Alfamedin Aliud Brand of Doxazosin Mesylate Alpharma Brand of Doxazosin Mesylate Almirall Brand of Doxazosin MesylateAlter Brand of Doxazosin Mesylate Apo Doxazosin Apo-Doxazosin

2934.99.9001

Powder      -20°C    3 years

                     4°C     2 years

In solvent   -80°C    6 months

                  -20°C    1 month

Room temperature (This product is stable at ambient temperature for a few days during ordinary shipping and time spent in Customs)

May dissolve in DMSO (in most cases), if not, try other solvents such as H2O, Ethanol, or DMF with a minute amount of products to avoid loss of samples

Note: Listed below are some common formulations that may be used to formulate products with low water solubility (e.g. < 1 mg/mL), you may test these formulations using a minute amount of products to avoid loss of samples.

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Injection Formulation 1: DMSO : Tween 80： Saline = 10 : 5 : 85 (i.e. 100 μL DMSO stock solution → 50 μL Tween 80 → 850 μL Saline)
*Preparation of saline: Dissolve 0.9 g of sodium chloride in 100 mL ddH ₂ O to obtain a clear solution.
Injection Formulation 2: DMSO : PEG300 ：Tween 80 : Saline = 10 : 40 : 5 : 45 (i.e. 100 μL DMSO → 400 μLPEG300 → 50 μL Tween 80 → 450 μL Saline)
Injection Formulation 3: DMSO : Corn oil = 10 : 90 (i.e. 100 μL DMSO → 900 μL Corn oil)
Example: Take the Injection Formulation 3 (DMSO : Corn oil = 10 : 90) as an example, if 1 mL of 2.5 mg/mL working solution is to be prepared, you can take 100 μL 25 mg/mL DMSO stock solution and add to 900 μL corn oil, mix well to obtain a clear or suspension solution (2.5 mg/mL, ready for use in animals).

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Injection Formulation 4: DMSO : 20% SBE-β-CD in saline = 10 : 90 [i.e. 100 μL DMSO → 900 μL (20% SBE-β-CD in saline)]
*Preparation of 20% SBE-β-CD in Saline (4°C，1 week): Dissolve 2 g SBE-β-CD in 10 mL saline to obtain a clear solution.
Injection Formulation 5: 2-Hydroxypropyl-β-cyclodextrin : Saline = 50 : 50 (i.e. 500 μL 2-Hydroxypropyl-β-cyclodextrin → 500 μL Saline)
Injection Formulation 6: DMSO : PEG300 : castor oil : Saline = 5 : 10 : 20 : 65 (i.e. 50 μL DMSO → 100 μLPEG300 → 200 μL castor oil → 650 μL Saline)
Injection Formulation 7: Ethanol : Cremophor : Saline = 10： 10 : 80 (i.e. 100 μL Ethanol → 100 μL Cremophor → 800 μL Saline)
Injection Formulation 8: Dissolve in Cremophor/Ethanol (50 : 50), then diluted by Saline
Injection Formulation 9: EtOH : Corn oil = 10 : 90 (i.e. 100 μL EtOH → 900 μL Corn oil)
Injection Formulation 10: EtOH : PEG300：Tween 80 : Saline = 10 : 40 : 5 : 45 (i.e. 100 μL EtOH → 400 μLPEG300 → 50 μL Tween 80 → 450 μL Saline)

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Oral Formulation 1: Suspend in 0.5% CMC Na (carboxymethylcellulose sodium)
Oral Formulation 2: Suspend in 0.5% Carboxymethyl cellulose
Example: Take the Oral Formulation 1 (Suspend in 0.5% CMC Na) as an example, if 100 mL of 2.5 mg/mL working solution is to be prepared, you can first prepare 0.5% CMC Na solution by measuring 0.5 g CMC Na and dissolve it in 100 mL ddH2O to obtain a clear solution; then add 250 mg of the product to 100 mL 0.5% CMC Na solution, to make the suspension solution (2.5 mg/mL, ready for use in animals).

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Oral Formulation 3: Dissolved in PEG400
Oral Formulation 4: Suspend in 0.2% Carboxymethyl cellulose
Oral Formulation 5: Dissolve in 0.25% Tween 80 and 0.5% Carboxymethyl cellulose
Oral Formulation 6: Mixing with food powders

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Note: Please be aware that the above formulations are for reference only. InvivoChem strongly recommends customers to read literature methods/protocols carefully before determining which formulation you should use for in vivo studies, as different compounds have different solubility properties and have to be formulated differently.

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 (Please use freshly prepared in vivo formulations for optimal results.)