A new radioimmunoassay for the determination of the angiotensin-converting enzyme inhibitor perindopril and its active metabolite in plasma and urine: advantages of a lysine derivative as immunogen to improve the assay specificity.
A new radioimmunoassay (RIA) was developed for the direct measurement of perindoprilate (PT), the active metabolite (diacid) of Perindopril (P), an angiotensin-converting enzyme (ACE) inhibitor. Antibodies were raised in rabbits against the lysine derivative of PT conjugated to bovine serum albumin. The p-hydroxyphenyl derivative of the lysine analogue was used for preparation of the radioligand by iodination (125I). Cross-reactivities for the glucuronide metabolites of P and PT are low (0.25 and 3.5%, respectively). The theoretical limit of detection is 0.2 nM, the sensitivity attainable with random samples is about 0.5 nM. Within- and between-assay variabilities observed were 4.2-6.7 and 2.8-5.9%, respectively (concentration range 2.1-41.7 nM). Serial dilution of plasma and urine samples showed excellent parallelism (r greater than 0.95; P less than 0.001). Recoveries of PT spiked to urine and plasma samples were 90-120%. The prodrug P can be measured in the same sample (plasma/urine) after chromatographic separation on a Dowex AG 1 x 2 anion-exchange column and quantitative alkaline hydrolysis of the P-containing fraction. It is concluded that the specificity and sensitivity of this assay are amply sufficient for pharmacokinetic studies and in patient monitoring.
van den Berg
H
H
TNO-CIVO Toxicology and Nutrition Institute, Department of Clinical Biochemistry, Zeist, The Netherlands.
Resplandy
G
G
de Bie
A T
AT
Floor
W
W
Bertrand
M
M
Arts
C J
CJ
D000806:Angiotensin-Converting Enzyme Inhibitors / Q000032:analysis* / Q000097:blood / Q000276:immunology / Q000652:urine; D000818:Animals; D000906:Antibodies / Q000276:immunology; D000918:Antibody Specificity; D000959:Antihypertensive Agents / Q000032:analysis* / Q000097:blood / Q000276:immunology / Q000652:urine; D003429:Cross Reactions; D007114:Immunization; D007211:Indoles / Q000032:analysis* / Q000097:blood / Q000276:immunology / Q000652:urine; D020913:Perindopril; D011485:Protein Binding; D011817:Rabbits; D011863:Radioimmunoassay / Q000379:methods*; D012680:Sensitivity and Specificity
D000806:Angiotensin-Converting Enzyme Inhibitors; D000906:Antibodies; D000959:Antihypertensive Agents; D007211:Indoles; C053500:perindoprilat; D020913:Perindopril