Pharmacokinetics and bioavailability of metoclopramide nasal spray versus metoclopramide intravenous in healthy volunteers and cancer patients

The kinetics and bioavailability of a new formulation of metoclopramide (CAS 364-62-5) nasal spray (MTC NS) were assessed in two separate studies versus the same drug administered intravenously (MTC IV) according to a balanced-block design where each study subject served as his own control. The first study involved 10 healthy subjects, each receiving metoclopramide NS 20 mg (one 10-mg puff per nostril) and metoclopramide IV 20 mg on two trial days separated by a 7-day washout period. On both occasions, blood samples were obtained at time 0 and at 20, 40, 60, 120, 150, 210, 280 and 360 min of dosing. Metoclopramide concentrations were assayed in plasma by HPLC. The second study involved 10 patients of oncologic domain, scheduled to receive mildly emetic chemotherapy regimes. The experimental design was similar to the one above except that blood was sampled at 0, 20, 40 and 60 min and again at 2, 3, 4, 6, and 8 h of dosing. All healthy subjects completed the trial without experiencing any adverse or untoward events, in the group of cancer patients, one subject dropped out after the nose spray treatment when he was removed to another department. This patient was replaced by another, and included in final data analysis only for the segment of treatment actually received. Metoclopramide kinetics after intravenous dosing were in good agreement with known data for the active substance, with no meaningful differences between healthy subjects and cancer patients. With MTC NS administration there was only a slight but significant difference of C(max), being lower in the cancer patient group (p <005). Said difference appears clinically irrelevant, since T(max) and AUC values compared closely in the two groups. Absolute bioavailability (MTC NS vs MTC IV) was 69% in the healthy subjects and 73% in the patient group. T(max) was between 2 and 3 after dosing, plasma elimination rate constants was in keeping with established metoclopramide data.