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The first dose phenomenon in ACEi is reduced and made safer by avoiding diuretics for 24 hours prior to first dose, taking first dose at night (so avoiding falls, etc) and starting on low doses and titrating upwards.
100:). This may occur with the class's better known side effect of dry cough (due to decreased breakdown of bradykinin), though there is no clear relationship between the two side effects.
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or greater. This adverse effect is self-limiting and in most cases does not recur after the initial period of therapy or during subsequent dose titration.
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Elliott HL, McLean K, Sumner DJ, Meredith PA, Reid JL (1981). "Immediate cardiovascular responses to oral prazosin—effects of concurrent beta-blockers".
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The cause is not clear. It occurs more commonly in patients who are salt and fluid volume depleted (as happens due to the use of
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88:(Minipress) should always be initiated with a low dose and should be taken at bedtime to avoid standing position.
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208:"Minipress (Prazosin HCl) drug warnings and precautions – prescription drugs and medications at RxList"
183:"Hytrin (Terazosin Hcl) drug warnings and precautions – prescription drugs and medications at RxList"
61:(Minipress) is most notorious for producing a first dose phenomenon. Other drugs of the same family,
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This effect is also observed after the administration of the first dose of drugs in the ACEi class (
50:(fainting). Syncope occurs in approximately 1% of patients given an initial dose of 2 mg
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usually happens shortly after the first dose is absorbed into the blood and can result in
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that can occur when changing from a lying to a standing position the first time that an
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Graham RM, Thornell IR, Gain JM, Bagnoli C, Oates HF, Stokes GS (1976).
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drug is used or when resuming the drug after many months off. This
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80:. Diuretics and beta blockers are frequently used to control
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Postural hypotension due to taking an alpha blocker drug
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Other drug classes with observed first dose hypotension
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98:angiotensin-converting enzyme inhibitor
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234:Clinical Pharmacology and Therapeutics
276:"Digital Medicines Information Suite"
135:"Prazosin: the first-dose phenomenon"
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32:first-dose phenomenon
246:10.1038/clpt.1981.40
44:postural hypotension
57:The alpha blocker
114:First pass effect
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82:hypertension
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120:References
74:diuretics
67:terazosin
63:doxazosin
290:Category
108:See also
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59:prazosin
52:prazosin
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160:1689975
48:syncope
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