Pemoline is synthesized by the condensation of racemic ethyl mandelate with guanidine. Examples include quinine, morphine and guanidine. Condensation with guanidine leads to the pyrimidone. These diguanides were less toxic and more potent than guanidine. GITC may also be recognized as guanidine thiocyanate. ZTX has a guanidine core similar to saxitoxin. Fatal bone-marrow suppression, apparently dose related, can occur with guanidine. Guanidine nitrate is the chemical compound with the formula [C(NH)]NO. Guanidine exists protonated, as guanidinium, in solution at physiological pH. Most guanidine derivatives are in fact salts containing the conjugate acid. The guanidine group of arginine residues condense with malondialdehyde to give 2-aminopyrimidines. In the 1920s, guanidine compounds were discovered in "Galega" extracts. Guanidine is the compound with the formula HNC(NH). Guanidine can be thought of as a nitrogenous analogue of carbonic acid. With a p"K" of 0.4, guanidine is a strong base.