Subcutaneous metoclopramide in the treatment of symptomatic gastroparesis: clinical efficacy and pharmacokinetics

We investigated the safety and efficacy of short-term s.c. administration of metoclopramide in the treatment of symptomatic gastric stasis. Ten patients with gastroparesis, documented by abnormal solid phase radionuclide gastric emptying study, were treated with 10 mg (2 ml) of s.c. metoclopramide every 6 hr for 3 days. Patients gave themselves the injections as outpatients. Questionnaires were then completed concerning symptom relief, local side effects and adverse reactions. A repeat gastric emptying study was obtained immediately after the last dose of metoclopramide. Serum metoclopramide concentrations were obtained at trough, 1, 2, 3, 4 and 5 hr postadministration and serum prolactin levels at trough, 1 and 3 hr. Pharmacokinetic analysis showed mean peak metoclopramide concentration at 30 min of 99.7 +/- 47.1 ng/ml with measured levels of 93.9 +/- 106.83 ng/ml at 60 min and return to trough values by 4 hr; trough prolactins remained elevated above normal values. Gastric stasis improved from a base-line retention of 78.7% of radioisotope at 2 hr to 72.5% after 3 days of therapy (P = .65). Eight patients reported significant improvement in symptomology and two patients reported lessening of symptoms such as nausea, vomiting, bloating, abdominal pain, heartburn and vomiting. The side effects were minimal and did not interfere with completion of the protocol. We demonstrated that s.c. administration of metoclopramide was well accepted by patients and resulted in subjective and objective improvement of gastric stasis. In addition, serum metoclopramide concentrations were comparable with other parenteral routes of administration. Furthermore, serum prolactin levels may provide both a bioassay of efficacy and a marker for monitoring compliance.