Lactulose is used as an adjunct to protein restriction and supportive therapy for the prevention and treatment of portal-systemic encephalopathy (PSE) including hepatic pre-coma and coma. Lactulose has been useful in the management of PSE resulting from surgical portacaval shunts or from chronic hepatic diseases such as cirrhosis. In patients with PSE, lactulose therapy reduces the blood ammonia concentration and this is usually accompanied by substantial improvement in the mental state of the patient and improved EEG tracings. Many patients are able to tolerate increased dietary protein during lactulose therapy. The drug does not, however, alter the course of the underlying liver disease. Therefore, use of lactulose in the treatment of PSE does not obviate treatment of underlying liver disease, nor preclude other measures used in the treatment of PSE.
A good clinical response has been achieved in 75-85% of PSE patients receiving lactulose therapy. Because lactulose is relatively nontoxic, it is a valuable alternative to antibiotics such as neomycin, especially when prolonged therapy is required or when neomycin is contraindicated. Some well-controlled comparative studies have shown that the efficacy of lactulose is superior to that of laxative controls (such as magnesium sulfate or sorbitol) and about equal to that of neomycin in the treatment of acute and chronic PSE. Some patients who had previously failed to respond to neomycin and dietary protein restriction responded to lactulose therapy. Conversely, other patients responded better to neomycin than to lactulose.
Since neomycin destroys bacteria and lactulose requires bacterial degradation for its effectiveness, concomitant therapy with these agents is theoretically counterproductive.
(See Drug Interactions: Anti-infective Agents.)It appears, however, that lactulose remains active when administered with neomycin and, in fact, there is some evidence that concomitant therapy with lactulose and neomycin may be more effective than either drug alone. Some clinicians recommend neomycin for acute episodes of PSE and lactulose for the long-term management of chronic PSE.
Lactulose is not useful in the management of non-nitrogenous types of encephalopathy such as those induced by drugs or metabolic or electrolyte disturbances. Lactulose therapy is not effective in the treatment of coma associated with infectious hepatitis or other acute disorders of the liver. In a case of hyperammonemia, which was apparently caused by an inborn error of metabolism, lactulose therapy was ineffective.
Lactulose is useful as a laxative in the treatment of chronic constipation in adults and geriatric patients. The drug has been used in the treatment of chronic constipation in children; however, the manufacturers state that safety and efficacy of lactulose for the treatment of chronic constipation in children have not been established. Lactulose has also been used to restore regular bowel movements in hemorrhoidectomy patients. Following a barium meal examination, the drug has been used to induce bowel evacuation in geriatric patients with colonic retention of barium and severe constipation. Although lactulose is effective in the treatment of chronic constipation, its superiority to conventional laxatives has not been established.