Covalent-5) learning objective: describe the different drug -receptor bonds.answer: ein general drugs binding to receptors in a reversible way and therefore the chemical bondbetween drug and receptor must be weak. a covalent bond is the strongest chemical bond (morethan 50 kcal/mole) and is rare in pharmacology. nevertheless some drugs can bind covalentlyand this often results in an irreversible action (examples are the covalent bond between someanticancer drugs and the dna, between phenoxybenzamine and alpha receptors, betweenorganophosphates and cholinesterase).a, b, c, d) the energy of all these chemical bonds is less than 10 kcal/mole.
