Аргипрессин

Hormone (antidiuretic).

ChEBI: The predominant form of mammalian vasopressin (antidiuretic hormone). It is a nonapeptide containing an arginine at residue 8 and two disulfide-linked cysteines at residues of 1 and 6.

ADH (vasopressin) is released primarily in response to increases in plasma osmolarity or decreases in blood volume. It produces its antidiuretic activity in the kidney, causing the cortical and medullary parts of the collecting duct to become more permeable to water, thereby increasing water reabsorption, reducing serum osmolarity, and increasing its volume. It produces this effect by binding to a subset of vasopressin receptors called V₂ that have relatively high affinity for the hormone. ADH also has actions at sites other than the kidney. V₂ receptors also mediate an increase in circulating levels of two proteins involved in blood coagulation: factor VIII and von Willebrand’s factor.At higher concentrations, ADH interacts with V1 receptors to cause a general constriction of most blood vessels. It also interacts with V₃ (or V_1b) receptors to increase ACTH release, although the major control of ACTH release occurs through corticotropin-releasing hormone.

Vasopressin tannate (PitressinTannate) is a water-insoluble tannate of vasopressin administeredintramuscularly (1.5–5.0 pressor units daily)for its prolonged duration of action by the slow release ofvasopressin. It is particularly useful for patients who havediabetes insipidus, but it should never be used intravenously.

A poison.

ADH itself is available for injections (Pitressin) but has a half-life of about 15 minutes. Desmopressin (DDAVP) is an analogue without an amino group at the first amino acid and with D-arginine instead of Larginine. This analogue is more stable and has very little pressor activity. Desmopressin can be given subcutaneously or nasally, and the effects last for 12 hours.

Because it is stable, desmopressin is preferred for treatments especially if pressor effects are not desired. The primary indication for therapy is central diabetes insipidus, a disorder that results when ADH secretion is reduced and that is characterized by polydipsia, polyuria, and dehydration. Desmopressin is also used to reduce primary nocturnal enuresis, or bedwetting, in children. It is useful in people with mild hemophilia A or with some types of von Willebrand’s disease, in which von Willebrand’s factor is present at low levels. In these cases, desmopressin is given when excessive bleeding occurs or before surgery to help reduce bleeding indirectly by increasing the amounts of coagulation factors. A possible adverse effect of desmopressin is water intoxication if too much is taken.
ADH antagonists, including nonpeptide analogues that may be taken orally, have been developed with specificity for each of the receptor types. In the future, those that block V1 receptors may be useful in treating hypertension, and those that block V2 receptors may be useful in any condition of excessive water retention or hyponatremia, for which so far there is no satisfactory therapeutic treatment.

A poison by intravenous route.When heated to decomposition it emits toxic vapors ofNOx and SOx.