<prompt> Tolvapton is aan -Angiotensin antagonistRenin inhibitorVasopressin antagonistACE inhibitor  <response>: Ans. is c i.e., Vasopressin antagonist VAPTANSo A new class of medication, the vaptan drugs, act by inhibiting the action of vasopressin on it receptors V1A, V1B and V2 - Vasopressin receptor antagonists. As already explained, V1 A receptors are involved in vasoconstriction - V1A antagonist can be used when total peripheral resistance is increased, e.g. in CHF and hypertension. Example - Relcovaptan2 V1 B receptor antagonist V1 B receptors are expressed in brain and pituitary gland - V1 B antagonist can be used as psychiatric drugs. Example - Nelivaptan3 V2 receptor antagonists V2 receptors are mainly responsible for increase water permeability in kidney - V2 antagonists can be used when there is excessive ADH induced fluid retention as in SIADH. Examples - Lixivaptan, satavaptan, mozavaptan, Tolvaptan.4 Non-selective mixed V1AV2 Can be used in CHF Examples - Conivaptan 