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Minipress (prazosin hydrochloride) dose, indications, adverse effects, interactions... from PDR.net

Minipress/Prazosin/Prazosin Hydrochloride Oral Cap: 1mg, 2mg, 5mg
DOSAGE & INDICATIONS
For the treatment of hypertension.
NOTE: A landmark clinical trial (ALLHAT) compared another alpha-blocker, doxazosin, to chlorthalidone in the treatment of high-risk hypertensive patients. In this study, only the diuretic significantly reduced the risk of combined cardiovascular disease events, especially heart failure. These results led to discontinuation of the alpha-blocker treatment arm of the study.
Oral dosage
Adults
Initially, 1 mg PO given 2 to 3 times per day. The first dose can be given at bedtime to minimize orthostatic hypotension. The average dosage is 6 to 15 mg/day PO, given in divided doses. Maximum dosage is 20 mg/day PO, given in divided doses; however, some patients may need higher doses up to 40 mg/day. When adding additional hypotensive agents or diuretics to prazosin therapy, decrease the dosage of prazosin to 1 to 2 mg PO 3 times per day, then gradually increase as needed.
Geriatric
Initially, 1 mg PO given 1 to 2 times per day. Elderly patients may be more sensitive to the hypotensive and adverse effects of prazosin. Adjust dosage based on clinical response.
Children
Initially, 5 mcg/kg PO every 6 hours. Increase dosage gradually to 25 mcg/kg PO every 6 hours. Maximum dosage is 15 mg/day or 400 mcg/kg/day PO. When stable, the total daily dosage can be divided into 2 to 3 doses.
For the treatment of hypertensive urgency, especially crises associated with increased circulating catecholamines.
Oral dosage
Initially, 10 to 20 mg PO. If needed, repeat dose in 30 minutes.
Geriatric
See adult dosage. Elderly patients may be more sensitive to the hypotensive and adverse effects of prazosin. Adjust dosage based on clinical response.
For the treatment of congestive heart failure.
NOTE: Long-term prazosin therapy has not been shown to produce beneficial hemodynamic effects or improve mortality in patients with congestive heart failure.
Oral dosage
Adults
Initially, 1 mg PO given 2 to 3 times per day. May increase gradually up to a maximum dosage of 20 mg/day PO, given in divided doses. The first dose can be given at bedtime to minimize orthostatic hypotension.
Geriatric
See adult dosage. Elderly patients may be more sensitive to the hypotensive and adverse effects of prazosin. Adjust dosage based on clinical response.
Children
Initially, 5 mcg/kg PO every 6 hours. Increase dosage gradually to 25 mcg/kg PO every 6 hours. Maximum dosage is 15 mg/day or 400 mcg/kg/day PO. When stable, the total daily dosage can be divided into 2 to 3 doses.
For the prevention of Raynaud's phenomenon.
Oral dosage
Adults
The dosage range is 0.5 to 3 mg PO twice daily. The first dose can be given at bedtime to minimize orthostatic hypotension. A small study revealed that doses greater than 6 mg/day PO were poorly tolerated. Efficacy may decrease with time.
Geriatric
See adult dosage. Elderly patients may be more sensitive to the hypotensive and adverse effects of prazosin. Adjust dosage based on clinical response.
For the treatment of symptomatic benign prostatic hyperplasia (BPH).
Oral dosage
Adults
Initially, 2 mg PO twice daily. The first dose can be given at bedtime to minimize orthostatic hypotension. The maintenance dosage range is 1 to 9 mg/day PO.
Geriatric
See adult dosage. Elderly patients may be more sensitive to the hypotensive and adverse effects of prazosin. Adjust dosage based on clinical response.
For the treatment of posttraumatic stress disorder (PTSD), particularly sleep-related disturbances (e.g., nightmares) .
For the treatment of nightmares associated with civilian-related PTSD.
Oral dosage
Adults
Initiate at 1 mg PO once daily at bedtime; may titrate up to 6 mg/day PO at bedtime as needed and tolerated. According to the 2009 American Psychiatric Association (APA) treatment guidelines, prazosin is among the most promising advances in the treatment of post-traumatic stress disorder (PTSD), specifically for treating trauma-related nightmares and sleep disruption. In one study evaluating civilian trauma PTSD (n = 13), patients initially received prazosin 1 mg or placebo PO at bedtime, with titration up to a maximum of 6 mg PO once daily at bedtime. The mean prazosin dose achieved was 3.1 +/- 1.3 mg (range 2 mg/day to 6 mg/day). In the prazosin group, trauma-related nightmares were significantly reduced, total sleep time increased by 94 minutes, and rapid eye movement (REM) sleep time and mean REM period duration increased without an alteration in sleep onset latency. Open-label studies and other published reports also suggest that prazosin is effective in reducing nightmares as well as improving general symptoms of refractory PTSD.
Adolescents >= 15 years
According to case reports, doses beginning with 1 mg PO once daily at bedtime and titrated to a range of 1.5 mg/day PO up to 4 mg/day PO once daily at bedtime have resulted in complete resolution of nightmares. Future study through controlled clinical trials is needed to formally assess the safety and efficacy of prazosin in trauma-related sleep disturbances in adolescents.
For the treatment of combat-related PTSD, including nightmares.
Oral dosage
Adults
Gradually titrate from low initial dosages (e.g., 1 mg/day PO at bedtime) up to an effective dose. Usual maximum dose: 15 mg/day PO (given in divided doses at varying time schedules); however, clinical studies did use higher titrations in men. According to the 2009 American Psychiatric Association (APA) treatment guidelines, prazosin is among the most promising advances in the treatment of post-traumatic stress disorder (PTSD), specifically trauma-related nightmares and sleep disruption. Prazosin may be particularly useful in combat-related nightmares since emerging evidence indicates that other widely used medications for PTSD, such as SSRIs, are not as effective in combat-related PTSD symptoms as in non-combat-related PTSD symptoms. In one placebo-controlled trial (n = 40), combat veterans with intractable trauma nightmares and other sleep disturbances were randomized to placebo or an initial prazosin dose of 1 mg PO at bedtime. The prazosin dose could be gradually titrated up to a maximum daily dose of 15 mg/day (5 mg in the morning and 10 mg at bedtime) if clinically indicated. The mean daily prazosin dose was 13 mg/day during the trial. Prazosin demonstrated efficacy in reducing the frequency and intensity of trauma-related nightmares, improving sleep quality, and decreasing overall PTSD symptoms severity. Similar results were observed in a separate trial (n = 10) with prazosin titration up to a maximum of 10 mg/day (6 mg PO at bedtime + 4 mg PO at 3 PM) if clinically indicated (mean total dose 9.5 mg/day). Prazosin was also effective in a third controlled trial evaluating the nightmare item of the Clinician-Administered PTSD Scale (CAPS), the Pittsburgh Sleep Quality Index, and the change item of the Clinical Global Impressions Scale anchored to functioning. The maximum allowed dose was 5 mg midmorning and 20 mg at bedtime for men and 2 mg midmorning and 10 mg at bedtime for women. Lower maximum morning and bedtime doses for women were chosen due to prior clinical observation of the investigators of an apparent increased sensitivity to both beneficial and adverse effects of prazosin in women with PTSD. At study end, the mean prazosin maintenance dose was 4 mg PO in the morning and 15.6 mg PO at bedtime for men, and 1.7 mg PO in the morning and 7 mg PO at bedtime for women. A subgroup analysis of patients randomized to receive prazosin who were established on SSRI therapy revealed a significant reduction in the treatment effect of prazosin in patients who were also receiving an SSRI for CAPS-dream scores, PSQI, and the total CAPS scores. Since a comparison was not made between prazosin patients on SSRIs and placebo patients on SSRIs, it cannot be determined whether this is a result of selection bias for treatment-resistant PTSD sufferers with severe PTSD required for study inclusion, or whether this represents evidence of an antagonistic effect of SSRI treatment on the clinical benefits of prazosin.
Indicates off-label use
MAXIMUM DOSAGE
Adults
20 mg/day PO for heart failure or hypertension (some patients have required up to 40 mg/day PO for hypertension); 9 mg/day PO for benign prostatic hyperplasia (BPH).
Elderly
20 mg/day PO for heart failure or hypertension (some patients have required up to 40 mg/day PO for hypertension); 9 mg/day PO for benign prostatic hyperplasia (BPH).
Adolescents
No maximum dosage information is available. See adult and children's dosage.
Children
15 mg/day PO or 400 mcg/kg/day PO.
DOSING CONSIDERATIONS
Hepatic Impairment
No specific recommendations are available for hepatic disease. Since prazosin is extensively metabolized, it is prudent to start with the lowest initial dosage (1 mg PO once daily at bedtime). Monitor and adjust dosage based on clinical response.
Renal Impairment
No dosage adjustment is needed.

Intermittent hemodialysis
No dosage adjustment is needed; prazosin is highly protein bound and is not significantly removed during hemodialysis.
ADMINISTRATION
Food delays the rate but not the extent of absorption of prazosin.
STORAGE
- Storage information not provided in labeling
CONTRAINDICATIONS / PRECAUTIONS
Angina, hypotension, orthostatic hypotension, syncope
The addition of prazosin to other antihypertensive agents can cause a rapid decrease in blood pressure. Prazosin should be used with caution in patients with angina pectoris because severe hypotension may cause or worsen angina. Prazosin can cause orthostatic hypotension and syncope, which can be hazardous for patients in certain occupations for which alertness is required. This effect can be dramatic after the initial dose (also known as the "first-dose effect").
Pregnancy
Prazosin is classified in FDA pregnancy risk category C. No adequate well-controlled studies in pregnant women have been done to assess the safety of prazosin use during pregnancy. Prazosin should be used in pregnancy only if the benefits to the mother outweigh the risks to the fetus.
Breast-feeding
Caution is advisable for breast-feeding mothers because prazosin distributes into breast milk. An alternative agent may be preferred for treating the patient's condition during lactation. Consider the benefits of breast-feeding, the risk of potential infant drug exposure, and the risk of an untreated or inadequately treated condition. If a breast-feeding infant experiences an adverse effect related to a maternally administered drug, healthcare providers are encouraged to report the adverse effect to the FDA.
Ocular surgery
Patients receiving or who have previously received treatment with alpha-1 blockers, such as prazosin, may be at risk for intraoperative floppy iris syndrome during surgery for cataracts (ocular surgery). Intraoperative floppy iris syndrome is a small pupil syndrome variant that is characterized by a flaccid iris that billows in response to intraoperative irrigation currents, progressive intraoperative miosis despite preoperative dilation with standard mydriatic drugs, and potential prolapse of the iris toward the phacoemulsification incisions. There does not appear to be a benefit of stopping alpha-1 blocker therapy prior to cataract surgery, but ophthalmologists should be prepared for possible modifications to their surgical technique such as the use of iris hooks, iris dilator rings, or viscoelastic substances.
Priapism
Prazosin, like other alpha adrenergic antagonists, has been associated with priapism (persistent painful penile erection unrelated to sexual activity). Priapism, if not treated promptly, can result in irreversible damage to the erectile tissue. Males who have an erection lasting greater than 4 hours, whether painful or not, should seek emergency medical attention.
Geriatric
Geriatric patients are more likely to be affected by postural hypotension and the possibility of syncope when administered prazosin. Orthostasis may occur frequently in this population, particularly with the first dose of the drug. According to the Beers Criteria, prazosin is considered a potentially inappropriate medication (PIM) for use in geriatric patients and should be avoided as routine treatment of hypertension in this population due to the high risk of orthostatic hypotension and the availability of alternative agents with a superior benefit to risk profile. In addition, the Beers expert panel recommends avoiding prazosin in geriatric patients with syncope due to an increased risk of orthostatic hypotension or bradycardia, and also avoiding prazosin in geriatric females with urinary incontinence, regardless of cause or type, because aggravation of incontinence may occur. The federal Omnibus Budget Reconciliation Act (OBRA) regulates medication use in residents of long-term care facilities (LTCFs). According to the OBRA guidelines, antihypertensive regimens should be individualized to achieve the desired outcome while minimizing adverse effects. Antihypertensives may cause dizziness, postural hypotension, fatigue, and there is an increased risk for falls. Prazosin can cause significant hypotension and syncope during the first few doses; therefore, the dose should be administered at bedtime initially, and the drug slowly titrated as needed. There are many drug interactions that can potentiate the effects of antihypertensives. Some agents require a gradual taper to avoid adverse consequences caused by abrupt discontinuation. In addition, in the rare cases when prazosin is used as a treatment for urinary incontinence, assessment of the underlying causes and identification of the type/category of urinary incontinence needs to be documented prior to or soon after the time of initiating treatment. These medications have specific and limited indications based on the cause and categorization of incontinence. Patients should be assessed periodically for medication effects on urinary incontinence as well as lower urinary tract symptoms and treatment tolerability.
ADVERSE REACTIONS
lichen planus-like eruption / Delayed / 0-1.0
tinnitus / Delayed / 0-1.0
insomnia / Early / Incidence not known
asthenia / Delayed / Incidence not known
gynecomastia / Delayed / Incidence not known
malaise / Early / Incidence not known
flushing / Rapid / Incidence not known
urticaria / Rapid / Incidence not known
ocular pain / Early / Incidence not known
DRUG INTERACTIONS
Acetaminophen; Chlorpheniramine; Dextromethorphan; Phenylephrine: (Major) Sympathomimetics can antagonize the effects of antihypertensives such as alpha-blockers when administered concomitantly.
Acetaminophen; Chlorpheniramine; Dextromethorphan; Pseudoephedrine: (Moderate) The cardiovascular effects of pseudoephedrine may reduce the antihypertensive effects produced by alpha-blockers. Monitor blood pressure and heart rate.
Acetaminophen; Chlorpheniramine; Phenylephrine; Phenyltoloxamine: (Major) Sympathomimetics can antagonize the effects of antihypertensives such as alpha-blockers when administered concomitantly.
Acetaminophen; Dextromethorphan; Guaifenesin; Phenylephrine: (Major) Sympathomimetics can antagonize the effects of antihypertensives such as alpha-blockers when administered concomitantly.
Acetaminophen; Dextromethorphan; Phenylephrine: (Major) Sympathomimetics can antagonize the effects of antihypertensives such as alpha-blockers when administered concomitantly.
Acetaminophen; Dextromethorphan; Pseudoephedrine: (Moderate) The cardiovascular effects of pseudoephedrine may reduce the antihypertensive effects produced by alpha-blockers. Monitor blood pressure and heart rate.
Acetaminophen; Dichloralphenazone; Isometheptene: (Major) Sympathomimetics can antagonize the antihypertensive effects of adrenergic agonists when administered concomitantly. Patients should be monitored for loss of blood pressure control.
Acetaminophen; Guaifenesin; Phenylephrine: (Major) Sympathomimetics can antagonize the effects of antihypertensives such as alpha-blockers when administered concomitantly.
Acetaminophen; Pseudoephedrine: (Moderate) The cardiovascular effects of pseudoephedrine may reduce the antihypertensive effects produced by alpha-blockers. Monitor blood pressure and heart rate.
Acrivastine; Pseudoephedrine: (Moderate) The cardiovascular effects of pseudoephedrine may reduce the antihypertensive effects produced by alpha-blockers. Monitor blood pressure and heart rate.
Aldesleukin, IL-2: (Moderate) Prazosin may potentiate the hypotension seen with aldesleukin, IL-2.
Alemtuzumab: (Moderate) Alemtuzumab may cause hypotension. Careful monitoring of blood pressure and hypotensive symptoms is recommended especially in patients with ischemic heart disease and in patients on antihypertensive agents.
Alfuzosin: (Severe) The pharmacokinetic and pharmacodynamic interactions between alfuzosin and other alpha-blockers (used for high blood pressure or for benign prostatic hyperplasia) have not been determined. However, interactions or side effects (dizziness, hypotension, syncope, etc.) may be expected from the duplication of pharmacologic effects, therefore, alfuzosin should not be administered in combination with other alpha-blockers.
Aliskiren: (Moderate) Prazosin is well-known to produce a 'first-dose' phenomenon. Some patients develop significant hypotension shortly after administration of the first dose. The first dose response (acute postural hypotension) of prazosin may be exaggerated in patients who are receiving beta-adrenergic blockers, diuretics, or other antihypertensive agents. Concomitant administration of prazosin with other antihypertensive agents is not prohibited, however. This can be therapeutically advantageous, but lower dosages of each agent should be used.
Aliskiren; Amlodipine: (Moderate) Prazosin is well-known to produce a 'first-dose' phenomenon. Some patients develop significant hypotension shortly after administration of the first dose. The first dose response (acute postural hypotension) of prazosin may be exaggerated in patients who are receiving beta-adrenergic blockers, diuretics, or other antihypertensive agents. Concomitant administration of prazosin with other antihypertensive agents is not prohibited, however. This can be therapeutically advantageous, but lower dosages of each agent should be used. (Moderate) Prazosin is well-known to produce a 'first-dose' phenomenon. Some patients develop significant hypotension shortly after administration of the first dose. The first dose response (acute postural hypotension) of prazosin may be exaggerated in patients who are receiving beta-adrenergic blockers, diuretics, or other antihypertensive agents. Concomitant administration of prazosin with other antihypertensive agents is not prohibited, however. This can be therapeutically advantageous, but lower dosages of each agent should be used. The use of alpha-blockers with verapamil can lead to excessive hypotension; In addition, verapamil has been reported to increase the AUC and Cmax of prazosin.
Aliskiren; Amlodipine; Hydrochlorothiazide, HCTZ: (Moderate) Prazosin is well-known to produce a 'first-dose' phenomenon. Some patients develop significant hypotension shortly after administration of the first dose. The first dose response (acute postural hypotension) of prazosin may be exaggerated in patients who are receiving beta-adrenergic blockers, diuretics, or other antihypertensive agents. Concomitant administration of prazosin with other antihypertensive agents is not prohibited, however. This can be therapeutically advantageous, but lower dosages of each agent should be used. (Moderate) Prazosin is well-known to produce a 'first-dose' phenomenon. Some patients develop significant hypotension shortly after administration of the first dose. The first dose response (acute postural hypotension) of prazosin may be exaggerated in patients who are receiving beta-adrenergic blockers, diuretics, or other antihypertensive agents. Concomitant administration of prazosin with other antihypertensive agents is not prohibited, however. This can be therapeutically advantageous, but lower dosages of each agent should be used. The use of alpha-blockers with verapamil can lead to excessive hypotension; In addition, verapamil has been reported to increase the AUC and Cmax of prazosin.
Aliskiren; Hydrochlorothiazide, HCTZ: (Moderate) Prazosin is well-known to produce a 'first-dose' phenomenon. Some patients develop significant hypotension shortly after administration of the first dose. The first dose response (acute postural hypotension) of prazosin may be exaggerated in patients who are receiving beta-adrenergic blockers, diuretics, or other antihypertensive agents. Concomitant administration of prazosin with other antihypertensive agents is not prohibited, however. This can be therapeutically advantageous, but lower dosages of each agent should be used.
Aliskiren; Valsartan: (Moderate) Prazosin is well-known to produce a 'first-dose' phenomenon. Some patients develop significant hypotension shortly after administration of the first dose. The first dose response (acute postural hypotension) of prazosin may be exaggerated in patients who are receiving beta-adrenergic blockers, diuretics, or other antihypertensive agents. Concomitant administration of prazosin with other antihypertensive agents is not prohibited, however. This can be therapeutically advantageous, but lower dosages of each agent should be used. (Moderate) razosin is well-known to produce a 'first-dose' phenomenon. Some patients develop significant hypotension shortly after administration of the first dose. The first dose response (acute postural hypotension) of prazosin may be exaggerated in patients who are receiving beta-adrenergic blockers, diuretics, or other antihypertensive agents. Concomitant administration of prazosin with other antihypertensive agents is not prohibited, however. This can be therapeutically advantageous, but lower dosages of each agent should be used.
Alprostadil: (Minor) The concomitant use of systemic alprostadil injection and antihypertensive agents, such as prazosin, may cause additive hypotension. Caution is advised with this combination. Systemic drug interactions with the urethral suppository (MUSE) or alprostadil intracavernous injection are unlikely in most patients because low or undetectable amounts of the drug are found in the peripheral venous circulation following administration. In those men with significant corpora cavernosa venous leakage, hypotension might be more likely. Use caution with in-clinic dosing for erectile dysfunction (ED) and monitor for the effects on blood pressure. In addition, the presence of medications in the circulation that attenuate erectile function may influence the response to alprostadil. However, in clinical trials with alprostadil intracavernous injection, anti-hypertensive agents had no apparent effect on the safety and efficacy of alprostadil.
Ambrisentan: (Moderate) Prazosin is well-known to produce a 'first-dose' phenomenon. The first dose response (acute postural hypotension) of prazosin may be exaggerated in patients who are receiving other antihypertensive agents. Lower dosages of each agent should be used.
Amifostine: (Major) Patients receiving alpha-blockers should be closely monitored during amifostine infusions due to additive effects. Patients receiving amifostine at doses recommended for chemotherapy should have antihypertensive therapy interrupted 24 hours preceding administration of amifostine. If the antihypertensive cannot be stopped, patients should not receive amifostine.
Amlodipine: (Moderate) Prazosin is well-known to produce a 'first-dose' phenomenon. Some patients develop significant hypotension shortly after administration of the first dose. The first dose response (acute postural hypotension) of prazosin may be exaggerated in patients who are receiving beta-adrenergic blockers, diuretics, or other antihypertensive agents. Concomitant administration of prazosin with other antihypertensive agents is not prohibited, however. This can be therapeutically advantageous, but lower dosages of each agent should be used. The use of alpha-blockers with verapamil can lead to excessive hypotension; In addition, verapamil has been reported to increase the AUC and Cmax of prazosin.
Amlodipine; Atorvastatin: (Moderate) Prazosin is well-known to produce a 'first-dose' phenomenon. Some patients develop significant hypotension shortly after administration of the first dose. The first dose response (acute postural hypotension) of prazosin may be exaggerated in patients who are receiving beta-adrenergic blockers, diuretics, or other antihypertensive agents. Concomitant administration of prazosin with other antihypertensive agents is not prohibited, however. This can be therapeutically advantageous, but lower dosages of each agent should be used. The use of alpha-blockers with verapamil can lead to excessive hypotension; In addition, verapamil has been reported to increase the AUC and Cmax of prazosin.
Amlodipine; Benazepril: (Moderate) Prazosin is well-known to produce a 'first-dose' phenomenon. Some patients develop significant hypotension shortly after administration of the first dose. The first dose response (acute postural hypotension) of prazosin may be exaggerated in patients who are receiving beta-adrenergic blockers, diuretics, or other antihypertensive agents. Concomitant administration of prazosin with other antihypertensive agents is not prohibited, however. This can be therapeutically advantageous, but lower dosages of each agent should be used. (Moderate) Prazosin is well-known to produce a 'first-dose' phenomenon. Some patients develop significant hypotension shortly after administration of the first dose. The first dose response (acute postural hypotension) of prazosin may be exaggerated in patients who are receiving beta-adrenergic blockers, diuretics, or other antihypertensive agents. Concomitant administration of prazosin with other antihypertensive agents is not prohibited, however. This can be therapeutically advantageous, but lower dosages of each agent should be used. The use of alpha-blockers with verapamil can lead to excessive hypotension; In addition, verapamil has been reported to increase the AUC and Cmax of prazosin.
Amlodipine; Hydrochlorothiazide, HCTZ; Olmesartan: (Moderate) Prazosin is well-known to produce a 'first-dose' phenomenon. Some patients develop significant hypotension shortly after administration of the first dose. The first dose response (acute postural hypotension) of prazosin may be exaggerated in patients who are receiving beta-adrenergic blockers, diuretics, or other antihypertensive agents. Concomitant administration of prazosin with other antihypertensive agents is not prohibited, however. This can be therapeutically advantageous, but lower dosages of each agent should be used. The use of alpha-blockers with verapamil can lead to excessive hypotension; In addition, verapamil has been reported to increase the AUC and Cmax of prazosin. (Moderate) razosin is well-known to produce a 'first-dose' phenomenon. Some patients develop significant hypotension shortly after administration of the first dose. The first dose response (acute postural hypotension) of prazosin may be exaggerated in patients who are receiving beta-adrenergic blockers, diuretics, or other antihypertensive agents. Concomitant administration of prazosin with other antihypertensive agents is not prohibited, however. This can be therapeutically advantageous, but lower dosages of each agent should be used.
Amlodipine; Hydrochlorothiazide, HCTZ; Valsartan: (Moderate) Prazosin is well-known to produce a 'first-dose' phenomenon. Some patients develop significant hypotension shortly after administration of the first dose. The first dose response (acute postural hypotension) of prazosin may be exaggerated in patients who are receiving beta-adrenergic blockers, diuretics, or other antihypertensive agents. Concomitant administration of prazosin with other antihypertensive agents is not prohibited, however. This can be therapeutically advantageous, but lower dosages of each agent should be used. The use of alpha-blockers with verapamil can lead to excessive hypotension; In addition, verapamil has been reported to increase the AUC and Cmax of prazosin. (Moderate) razosin is well-known to produce a 'first-dose' phenomenon. Some patients develop significant hypotension shortly after administration of the first dose. The first dose response (acute postural hypotension) of prazosin may be exaggerated in patients who are receiving beta-adrenergic blockers, diuretics, or other antihypertensive agents. Concomitant administration of prazosin with other antihypertensive agents is not prohibited, however. This can be therapeutically advantageous, but lower dosages of each agent should be used.
Amlodipine; Olmesartan: (Moderate) Prazosin is well-known to produce a 'first-dose' phenomenon. Some patients develop significant hypotension shortly after administration of the first dose. The first dose response (acute postural hypotension) of prazosin may be exaggerated in patients who are receiving beta-adrenergic blockers, diuretics, or other antihypertensive agents. Concomitant administration of prazosin with other antihypertensive agents is not prohibited, however. This can be therapeutically advantageous, but lower dosages of each agent should be used. The use of alpha-blockers with verapamil can lead to excessive hypotension; In addition, verapamil has been reported to increase the AUC and Cmax of prazosin. (Moderate) razosin is well-known to produce a 'first-dose' phenomenon. Some patients develop significant hypotension shortly after administration of the first dose. The first dose response (acute postural hypotension) of prazosin may be exaggerated in patients who are receiving beta-adrenergic blockers, diuretics, or other antihypertensive agents. Concomitant administration of prazosin with other antihypertensive agents is not prohibited, however. This can be therapeutically advantageous, but lower dosages of each agent should be used.
Amlodipine; Telmisartan: (Moderate) Prazosin is well-known to produce a 'first-dose' phenomenon. Some patients develop significant hypotension shortly after administration of the first dose. The first dose response (acute postural hypotension) of prazosin may be exaggerated in patients who are receiving beta-adrenergic blockers, diuretics, or other antihypertensive agents. Concomitant administration of prazosin with other antihypertensive agents is not prohibited, however. This can be therapeutically advantageous, but lower dosages of each agent should be used. The use of alpha-blockers with verapamil can lead to excessive hypotension; In addition, verapamil has been reported to increase the AUC and Cmax of prazosin. (Moderate) razosin is well-known to produce a 'first-dose' phenomenon. Some patients develop significant hypotension shortly after administration of the first dose. The first dose response (acute postural hypotension) of prazosin may be exaggerated in patients who are receiving beta-adrenergic blockers, diuretics, or other antihypertensive agents. Concomitant administration of prazosin with other antihypertensive agents is not prohibited, however. This can be therapeutically advantageous, but lower dosages of each agent should be used.
Amlodipine; Valsartan: (Moderate) Prazosin is well-known to produce a 'first-dose' phenomenon. Some patients develop significant hypotension shortly after administration of the first dose. The first dose response (acute postural hypotension) of prazosin may be exaggerated in patients who are receiving beta-adrenergic blockers, diuretics, or other antihypertensive agents. Concomitant administration of prazosin with other antihypertensive agents is not prohibited, however. This can be therapeutically advantageous, but lower dosages of each agent should be used. The use of alpha-blockers with verapamil can lead to excessive hypotension; In addition, verapamil has been reported to increase the AUC and Cmax of prazosin. (Moderate) razosin is well-known to produce a 'first-dose' phenomenon. Some patients develop significant hypotension shortly after administration of the first dose. The first dose response (acute postural hypotension) of prazosin may be exaggerated in patients who are receiving beta-adrenergic blockers, diuretics, or other antihypertensive agents. Concomitant administration of prazosin with other antihypertensive agents is not prohibited, however. This can be therapeutically advantageous, but lower dosages of each agent should be used.
Amobarbital: (Moderate) Concurrent use of amobarbital with antihypertensive agents may lead to hypotension. Monitor for decreases in blood pressure during times of coadministration.
Amphetamines: (Major) Amphetamines increase both systolic and diastolic blood pressure and may counteract the activity of some antihypertensive agents. Due to the risk of unopposed alpha-adrenergic activity, amphetamines should be used cautiously with beta-blockers. Increased blood pressure, bradycardia, or heart block may occur due to excessive alpha-adrenergic receptor stimulation. In particular, amphetamines can inhibit the antihypertensive response to guanadrel, an adrenergic antagonist that causes depletion of norepinephrine in the synapse. Close monitoring of blood pressure or the selection of alternative therapeutic agents may be needed.
Amyl Nitrite: (Moderate) Concomitant use of nitrates with other antihypertensive agents can cause additive hypotensive effects. Dosage adjustments may be necessary.
Angiotensin II receptor antagonists: (Moderate) razosin is well-known to produce a 'first-dose' phenomenon. Some patients develop significant hypotension shortly after administration of the first dose. The first dose response (acute postural hypotension) of prazosin may be exaggerated in patients who are receiving beta-adrenergic blockers, diuretics, or other antihypertensive agents. Concomitant administration of prazosin with other antihypertensive agents is not prohibited, however. This can be therapeutically advantageous, but lower dosages of each agent should be used.
Angiotensin-converting enzyme inhibitors: (Moderate) Prazosin is well-known to produce a 'first-dose' phenomenon. Some patients develop significant hypotension shortly after administration of the first dose. The first dose response (acute postural hypotension) of prazosin may be exaggerated in patients who are receiving beta-adrenergic blockers, diuretics, or other antihypertensive agents. Concomitant administration of prazosin with other antihypertensive agents is not prohibited, however. This can be therapeutically advantageous, but lower dosages of each agent should be used.
Apomorphine: (Moderate) Patients receiving apomorphine may experience orthostatic hypotension, hypotension, and/or syncope. Extreme caution should be exercised if apomorphine is used concurrently with antihypertensive agents, or vasodilators such as nitrates.
Apraclonidine: (Minor) Alpha blockers as a class may reduce heart rate and blood pressure. While no specific drug interactions have been identified with systemic agents and apraclonidine during clinical trials, it is theoretically possible that additive blood pressure reductions could occur when apraclonidine is combined with the use of antihypertensive agents. Patients using cardiovascular drugs concomitantly with apraclonidine should have their pulse and blood pressure monitored periodically.
Aripiprazole: (Minor) Aripiprazole may enhance the hypotensive effects of antihypertensive agents.
Articaine; Epinephrine: (Major) Sympathomimetics, such as epinephrine, can antagonize the effects of alpha-blockers when administered concomitantly. Patients receiving alpha-blockers can exhibit a decreased pressor response to epinephrine, resulting in an increased risk of developing hypotension and tachycardia. Blood pressure should be monitored closely.
Asenapine: (Moderate) Secondary to alpha-blockade, asenapine can produce vasodilation that may result in additive effects during concurrent use of antihypertensive agents. The potential reduction in blood pressure can precipitate orthostatic hypotension and associated dizziness, tachycardia, and syncope. If concurrent use of asenapine and antihypertensive agents is necessary, patients should be counseled on measures to prevent orthostatic hypotension, such as sitting on the edge of the bed for several minutes prior to standing in the morning and rising slowly from a seated position. Close monitoring of blood pressure is recommended until the full effects of the combination therapy are known.
Avanafil: (Major) Concurrent use of avanafil and alpha-blockers may lead to symptomatic hypotension in some patients. Avanafil, a phosphodiesterase (PDE5) inhibitor, and alpha-blockers are systemic vasodilators which can lower blood pressure. If vasodilators are used in combination, an additive effect on blood pressure is anticipated. Patients should be stable on alpha-blocker therapy before starting PDE5 inhibitor therapy. If hemodynamic instability is evident on alpha-blocker therapy alone, there is an increased risk of symptomatic hypotension with concomitant PDE5 inhibitor therapy. For patients who are stable on alpha-blocker therapy, PDE5 inhibitors should be started at the 50 mg dose. If a patient is currently receiving an optimized dose of a PDE5 inhibitor, alpha-blocker therapy should be initiated at the lowest dose. Stepwise increases in the alpha-blocker dose may be associated with further hypotension when taking a PDE5 inhibitor. Other variables, such as intravascular volume depletion and other antihypertensive drugs, may affect the safety of concomitant use of PDE5 inhibitors and alpha-blockers.
Azelaic Acid; Copper; Folic Acid; Nicotinamide; Pyridoxine; Zinc: (Moderate) Cutaneous vasodilation induced by niacin may become problematic if high-dose niacin is used concomitantly with other antihypertensive agents. (Moderate) Cutaneous vasodilation induced by niacin may become problematic if high-dose niacin is used concomitantly with other antihypertensive agents. This effect is of particular concern in the setting of acute myocardial infarction, unstable angina, or other acute hemodynamic compromise.
Azilsartan: (Moderate) razosin is well-known to produce a 'first-dose' phenomenon. Some patients develop significant hypotension shortly after administration of the first dose. The first dose response (acute postural hypotension) of prazosin may be exaggerated in patients who are receiving beta-adrenergic blockers, diuretics, or other antihypertensive agents. Concomitant administration of prazosin with other antihypertensive agents is not prohibited, however. This can be therapeutically advantageous, but lower dosages of each agent should be used.
Azilsartan; Chlorthalidone: (Moderate) razosin is well-known to produce a 'first-dose' phenomenon. Some patients develop significant hypotension shortly after administration of the first dose. The first dose response (acute postural hypotension) of prazosin may be exaggerated in patients who are receiving beta-adrenergic blockers, diuretics, or other antihypertensive agents. Concomitant administration of prazosin with other antihypertensive agents is not prohibited, however. This can be therapeutically advantageous, but lower dosages of each agent should be used.
Baclofen: (Moderate) Baclofen has been associated with hypotension. Concurrent use with baclofen and antihypertensive agents may result in additive hypotension. Dosage adjustments of the antihypertensive medication may be required.
Benazepril: (Moderate) Prazosin is well-