A radioimmunoassay for metoclopramide.
A radioimmunoassay for the anti-emetic drug, metoclopramide, in the pmol range was developed. The immunogen was prepared by photolytic coupling of metoclopramide to bovine serum albumin. A crosslinking reagent, N-hydroxy-succinimidyl-4-azidobenzoate, was first reacted with serum albumin through nucleophilic substitution. Ultraviolet irradiation (lambda greater than 300 nm) of the photoactive serum albumin conjugate in the presence of metoclopramide resulted in covalent attachment of the drug to the protein. An 125I-labelled metoclopramide derivative was prepared by diazotisation of the aromatic amine group and substitution of the resultant diazo group with 125I-. Binding data of the antibody with radioiodinated metoclopramide gave a linear Scatchard plot indicative of a homogeneous antibody population. A dissociation constant of 3 X 10(-11) mol/l was calculated for the antigen-antibody interaction. The antibodies showed negligible cross-reactivity with lignocaine which is structurally closely related to metoclopramide.
De Villiers
M
M
Department of Pharmacology, University of Stellenbosch Medical School, Tygerberg, Republic of South Africa.
Parkin
D
D
Van Jaarsveld
P
P
Van der Walt
B
B
D000418:Albumins / Q000276:immunology; D000818:Animals; D000906:Antibodies / Q000276:immunology / Q000302:isolation & purification; D000915:Antibody Affinity; D008297:Male; D008787:Metoclopramide / Q000032:analysis* / Q000276:immunology; D011817:Rabbits; D011863:Radioimmunoassay
D000418:Albumins; D000906:Antibodies; D008787:Metoclopramide