Patients must stop taking desmopressin if they develop severe vomiting and diarrhea, fever, the flu, or severe cold. Patients should also be very cautious about taking desmopressin during hot weather conditions or following strenuous exercise, as these conditions can place stress on the bodys electrolyte and water balance. A body needs to maintain a balance of water and (sodium). If sodium levels become too low (hyponatremia) – either as a result of increased water take-up or reduced salt levels – a person may have seizures and, in extreme cases, may die. Mechanism of action
Desmopressin works by limiting the amount of water that is eliminated in the urine; that is, it is an antidiuretic. It works at the level of the renal collecting duct by binding to V2 receptors, which signal for the translocation of aquaporin channels via cytosolic vesicles to the apical membrane of the collecting duct. The presence of these aquaporin channels in the distal nephron causes increasing water reabsorption from the urine, which becomes passively re-distributed from the nephron to systemic circulation by way of basolateral membrane channels. Desmopressin also stimulates release of von Willebrand factor from endothelial cells by acting on the V2 receptor. It also increases endogenous levels of factor VIII, making it useful in the treatment of hemophilia A.Desmopressin is degraded more slowly than recombinant vasopressin, and requires less frequent administration. In addition, it has little effect on blood pressure, while vasopressin may cause arterial hypertension.
Pain researchers such as Tamar Makin (Oxford) and Marshall Devor (Hebrew University, Jerusalem) argue that phantom limb pain is primarily the result of "junk" inputs from the peripheral nervous system.Despite a great deal of research on the underlying neural mechanisms of phantom limb pain there is still no clear consensus as to its cause. Both the brain and the peripheral nervous system may be involved.Research continues into more precise mechanisms and explanations. Neural mechanisms
Pain, temperature, touch, and pressure information are carried to the central nervous system via the anterolateral system (spinothalamic tracts, spinoreticular tract, spinomesencefalic tract), with pain and temperature information transferred via lateral spinothalamic tracts to the primary sensory cortex, located in the postcentral gyrus in the parietal lobe, where sensory information is represented somatotropically, forming the sensory homunculus.In phantom limb syndrome, there is sensory input indicating pain from a part of the body that is no longer existent. This phenomenon is still not fully understood, but it is hypothesized that it is caused by activation of the somatosensory cortex. Treatment
Most approaches to treatment over the past two decades have not shown consistent symptom improvement. Treatment approaches have included medication such as antidepressants, spinal cord stimulation, vibration therapy, acupuncture, hypnosis, and biofeedback. Reliable evidence is lacking on whether any treatment is more effective than the others. Most treatments are not very effective. Ketamine or morphine may be useful around the time of surgery. Morphine may be helpful for longer periods of time. Evidence for gabapentin is mixed.