Cymbalta and Pristiq are prescription drugs classified as serotonin norepinephrine reuptake inhibitors. Cymbalta is the brand name of duloxetine and Pristiq is the brand name of desvenlafaxine. Both of the medications block the reabsorption of serotonin and norepinephrine in the brain. Cymbalta weakly inhibits a third chemical called dopamine. This leads to the normalization of the levels of these chemicals. Although these medications are similar, they differ in their use and effect on the patient.

Indications

Pristiq and Cymbalta are indicated for the treatment of major depressive disorder. Cymbalta is also indicated for the treatment of generalized anxiety disorder and the management of fibromyalgia. Cymbalta treats pain and tingling caused by diabetic neuropathy, which is nerve damage that may occur in uncontrolled diabetes.

Dosage and Administration

Pristiq is available as extended release tablets in 50 and 100 mg doses. The usual dose is 50 mg and may be increased as needed up to 400 mg a day, according to the “Drug Information Handbook.” The tablet should be swallowed whole and may be taken with or without food. Cymbalta is a delayed release, enteric-coated capsule available in 20 mg, 30 mg and 60 mg. The capsule must be swallowed whole with a full glass of water. The usual dose for major depressive disorder is 40 to 60 mg as a single daily dose or in two divided doses. Patients with generalized anxiety disorder are administered 30 to 60 mg a day. The usual dose in patients with diabetic neuropathy is 60 mg once daily. Patients with fibromyalgia are given 30 mg a day for the first week of therapy and then increased to 60 mg a day.

Creatinine Clearance

Dosage adjustments are determined by the patient’s creatinine clearance, which measures how well the patient eliminates wastes from the body.

Pristiq does not require dosage adjustment if the creatinine clearance is above 50 mL per minute. If the creatinine clearance is between 30 and 50 mL per minute, the maximum daily dose is 50 mg. The maximum dose is 50 mg every other day when the creatinine clearance falls below 30 mL per minute. Patients on hemodialysis must not receive more than 50 mg ever other day.

In the case of Cymbalta, it is not recommended for use in patients who have creatinine clearance less than 30 mL per minute or in end stage renal disease, states RxList.com. In patients with mild to moderate kidney impairment, lower starting doses may be needed and increased according to the patient’s response.

Liver Function

Pristiq requires dosage adjustment in patients with liver impairment. The initial dose is 50 mg once daily with a maximum dose of 100 mg a day. Cymbalta, on the other hand, is not recommended for use in patients with liver impairment.