Inclusion Criteria:

Male or female patients, 18 years of age or older, who are eligible for chemotherapy may participate in the trial if the following criteria are met:

1. Patients must have a diagnosis of malignant disease and be scheduled to receive single-day intravenous chemotherapy drug or combination of drugs that are considered to elicit level 3, 4 or 5 emesis (appendix A).
2. Males must be surgically sterilized, or agree to practice adequate contraceptive precautions during the study.
3. Females of non-childbearing potential (i.e. those who have been surgically sterilized, or who are at least one-year post menopausal) may enter the study. Females of childbearing potential must have a negative pregnancy test (urine or serum hCG) before entry into the study, and must agree to practice adequate contraceptive precautions during the study.
4. Written informed consent must be obtained before initiating any protocol specified procedures.

Exclusion Criteria:

Patients with any of the following are not eligible for enrollment in the study.

1. Any unstable medical disorder.
2. Participation in any drug trial in which the patient received an investigational drug within 30 days or 5 half-lives (whichever is longer) preceding the screening phase of this study.

3. Patients with serum creatinine ≥ 2 dL/mL; bilirubin ≥ 3 times ULN; or those with an ECOG performance status

   • 3.
4. Patients with severe hepatic insufficiency as evidenced by ascites, encephalopathy, coagulopathy, or jaundice.
5. Patients prescribed corticosteroids except for replacement or maintenance doses up to 10mg prednisone or equivalent. Dexamethasone is permitted as a prophylactic component of the pre- and post-chemotherapy anti-emetic regimen as defined in this protocol.

6. Primary or secondary (from metastatic disease) brain neoplasm with:

   • Signs or symptoms of increased intracranial pressure or
   • Patients with brain metastases requiring treatment within 30 days of entry into the study.

   Signs or symptoms of cerebral edema will exclude a patient from entry into the study. Patients with symptomatically "silent" metastases may be enrolled into the study.

7. Patients who are known to be hypersensitive to gabapentin, any neurokinin-1 or dopamine receptor antagonist, 5-HT3 receptor antagonists, or corticosteroids.
8. Patients who are unwilling or unable to comply with the protocol.
9. Patients are excluded if they are receiving radiation therapy to any abdominal field (T10-L5) within 24 hours before the dose of study medication is given or if they are scheduled to receive such radiation during the period of assessment (study days 0-2 for arm A and study days 0-6 for arm B). Radiation to other fields is acceptable (e.g. pelvic radiation, thoracic radiation).
10. Patients who have had any nausea within one hour and/or emesis (vomiting and/or retching) within 24 hours before dosing of study medication.
11. Patients who have taken either gabapentin or aprepitant within four weeks of randomization.