Description of the medicine: Urea (Urea pura)
UREA (Urea pura).
Synonyms: Carbamide, Carbamid, Carbamidum, Ureaphil.
White crystalline powder or colorless crystals with a salty-bitter taste, odorless. Easily soluble in water (1: 1), soluble in alcohol (1: 5).
Aqueous solutions have a neutral reaction. Dissolution in water occurs with the absorption of heat.
Urea has been used in the past as a diuretic. She was prescribed orally (usually in sugar or fruit syrup), 15 to 20 g per reception 2 to 5 times a day. At these doses, it has a diuretic effect, but in case of impaired renal function, the nitrogen content in the body can increase dramatically. The diuretic effect is associated with the action of whole urea molecules; in the human body they are not subjected to metabolic processes and are filtered in large quantities (50-60%) through the glomeruli without reverse absorption. The high osmotic pressure created in the tubules causes strong water diuresis.
Currently, in connection with the advent of new effective diuretic agents, urea is not used for this purpose.
Urea is prescribed mainly as a dehydrating agent to prevent and reduce cerebral edema and toxic pulmonary edema, as well as an effective means of lowering intraocular pressure.
The mechanism of the anti-edematous effect and hypotensive effect (with respect to intraocular pressure) of urea is not clear enough. It is believed that the osmotic effect plays an important role. A sharp increase in the osmotic pressure of the blood, caused by the introduction of hypertonic solutions of urea, leads to the active intake of fluid from the tissues and organs, including from the cavities and tissues of the brain and eye. Urea penetrates poorly through the blood-brain barrier and into the eyeball; thus, a significant difference is created between the osmotic pressure of the blood, on the one hand, and cerebrospinal fluid and eye fluids, on the other. The antihypertensive effect with respect to intracranial and intraocular pressure is not directly related to the diuretic effect. It was found that under experimental conditions the hypotensive effect persists after bilateral nephrectomy. However, the diuretic effect helps to lower the pressure. There is also evidence to suggest that a certain role in the hypotensive effect is played by central mechanisms (the effect of hypertonic solution on osmoreceptive fields in the hypothalamus).
Urea has found application in neurosurgery to prevent and reduce cerebral edema, especially in the early stages of its development.
In ophthalmic practice, urea is prescribed for glaucoma, especially during an acute attack, as well as in preparing patients with a high level of ophthalmotonus for operations.
Apply urea intravenously, as well as inside.