Document Detail

Comparative first dose effects of prazosin and tiodazosin (BL-5111) in spontaneously hypertensive rats.
MedLine Citation:
PMID:  441514     Owner:  NLM     Status:  MEDLINE    
Prazosin produces a "first-dose" phenomenon in man clinically characterized by an exaggerated hypotensive response to the initial dose of the drug, with subsequent doses not producing this exaggerated effect. In spontaneously hypertensive rats (SHR), prazosin (1 mg kg po) produced a similar effect, appreciably reducing systolic blood pressure at 12 hours after the first dose but having little or no effect at 12 hours after the subsequent doses. In contrast, BL-5111, an antihypertensive agent similar in chemical structure and shown in previous studies to be slightly less potent than prazosin but with appreciably less alpha-adrenergic receptor antagonist activity, had no effect on blood pressure at 12 hours after dosing (1 and 2 mg/kg po). Pretreatment of rats with an ineffective blood pressure lowering dose of prazosin (0.03 mg/kg po) significantly attenuated the first dose effect of prazosin, resembling the clinical observations seen in patients. Thus, the SHR may be a useful model for predicting the prazosin-like "first-dose" phenomenon with related analogs.
L E Roebel; A P Florczyk; J P Buyniski
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Publication Detail:
Type:  Comparative Study; Journal Article    
Journal Detail:
Title:  Research communications in chemical pathology and pharmacology     Volume:  23     ISSN:  0034-5164     ISO Abbreviation:  Res. Commun. Chem. Pathol. Pharmacol.     Publication Date:  1979 Jan 
Date Detail:
Created Date:  1979-07-25     Completed Date:  1979-07-25     Revised Date:  2006-11-15    
Medline Journal Info:
Nlm Unique ID:  0244734     Medline TA:  Res Commun Chem Pathol Pharmacol     Country:  UNITED STATES    
Other Details:
Languages:  eng     Pagination:  29-35     Citation Subset:  IM    
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MeSH Terms
Antihypertensive Agents / administration & dosage,  pharmacology*
Blood Pressure / drug effects
Hypertension / physiopathology*
Prazosin / administration & dosage,  analogs & derivatives,  pharmacology*
Quinazolines / pharmacology*
Time Factors
Reg. No./Substance:
0/Antihypertensive Agents; 0/Quinazolines; 19216-56-9/Prazosin

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine

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