Study of Diazepam Buccal Film Administered in the Interictal and in the Ictal-Periictal States to Adults With Epilepsy

Inclusion Criteria: Potential subjects meeting all of the following criteria may be included in the study: 1. Subjects scheduled for admission to the institution's EMU, GCRC (General Clinical Research Center) or similar facility for evaluation within 28 days. 2. Male and female subjects between 18 to 65 years of age, inclusive. 3. Subjects having a body weight of ≥ 40 kg to 111 kg. 4. Subjects have a clinical diagnosis of epilepsy and are scheduled to be admitted to an Epilepsy Monitoring Unit (EMU) for extracranial video-Electroencephalogram (EEG) recording of a seizure event for evaluation of their epilepsy. 5. Subjects have an average frequency of \> 1 seizure every 3 days or \> 10 seizures / month as documented by seizure diaries dispensed at the Screening Visit and verified prior to initiation of Period A or Period B. 6. Female subjects have a negative serum pregnancy test at Screening. Female subjects of childbearing potential (i.e., not surgically sterile or 2 years postmenopausal) must have a negative pregnancy test at screening and a partner who is sterile, agree to abstinence, be practicing double barrier contraception or using an FDA approved contraceptive (e.g., licensed hormonal or barrier methods) for greater than 2 months prior to screening visit and commit to an acceptable form of birth control for the duration of the study and for 30 days after participation in the study. 7. Subjects are currently receiving at least one antiepileptic medication. 8. Subjects or subject's legally authorized representative (LAR) must be willing and able to complete informed consent/assent and HIPAA authorization. 9. Subjects must agree and must be willing to comply with all required study procedures while in the EMU or GCRC. 10. Ability to comprehend and be informed of the nature of the study, as assessed by the PI or Sub-Investigator. 11. Ability to consume standard meals. 12. Availability to volunteer for the entire study duration and willing to adhere to all protocol requirements. Exclusion Criteria: Potential subjects meeting any of the following criteria will be excluded: 1. Subjects having a progressive neurological disorder such as brain tumor, demyelinating disease, or degenerative central nervous system (CNS) disease that is likely to progress in the next 12 months. 2. Subjects having respiratory failure (or is at risk for respiratory failure) or other severe cardiorespiratory disease with New York Heart Association Class III or IV functional status, or requires supplemental oxygen. 3. Female subjects who are lactating or positive serum pregnancy test (ß-hCG) at screening for female subjects ≥12 years of age. 4. Subjects with severe psychiatric disease that in the Investigator's judgment would prevent the patient's successful completion of the study. 5. Subjects who have an episode of status epilepticus, as determined by the Principal Investigator/Sub-Investigator, at any time during Period B (EMU, GCRC or similar facility Visit 6. Subjects with known history or presence of any clinically significant hepatic (e.g. hepatic impairment), renal/genitourinary (renal impairment, kidney stones), psychiatric, dermatological or hematological disease or condition unless determined as not clinically significant by the Principal Investigator/Sub-Investigator and confirmed by Sponsor via written communication prior to subject enrollment. 7. Subjects with any clinically significant illness other than epilepsy within 30 days prior to first dosing, as determined by the Principal Investigator/Sub-Investigator. 8. Subjects with any significant physical or organ abnormality as determined by the Principal Investigator/Sub-Investigator. 9. Subjects with any significant lesion of the oral cavity or having oral prophylactic procedures within 30 days prior to first dosing. 10. Subjects with a QTc interval QTcF\>450 msec for males and QTcF\>470 msec for females on screening ECG, unless determined as not clinically significant by the Investigator. 11. Subjects with a positive test result for any of the following: drugs of abuse (amphetamines, cocaine, opiates, or phencyclidine), a positive breath alcohol test. 12. Subjects with a known history or presence of: a. Alcohol abuse or dependence within one year prior to first drug administration; b. Drug abuse or dependence; c. Hypersensitivity or idiosyncratic reaction to diazepam, its excipients, sodium phosphates; and/or related substances, e.g. benzodiazepines; d. Glaucoma (open or acute narrow angle); e. Severe allergic reactions (e.g. anaphylactic reactions, angioedema 13. Subjects who have participated in another clinical trial or who received an investigational drug within 30 days prior to first drug administration or 5 half-lives of the investigational drug-whichever is the longer period. 14. Blood or plasma donation within 30 days prior to Screening 15. Subjects not willing or unable to tolerate blood draws. 16. Subjects who have received any other dosage form of diazepam or benzodiazepines within 2 weeks prior to entering Period A or Period B. 17. Consumption of alcohol within 48 hours before dosing and food or beverages containing grapefruit, star fruit, Seville oranges, and/or pomelo or their derived products (e.g., fruit juice) within 10 days prior to first drug administration. 18. Use of any enzyme-modifying drugs, including strong inhibitors of cytochrome P450 (CYP) enzymes (e.g. cimetidine, fluoxetine, quinidine, erythromycin, ciprofloxacin, fluconazole, ketoconazole, diltiazem, or HIV antivirals) and strong inducers of CYP enzymes (e.g. glucocorticoids, St. John´s Wort, or rifampicin) in the previous 30 days before first drug administration \[barbiturates, carbamazepine, and phenytoin are allowed since these are common AEDs (Anti-epileptic drugs)\]. 19. Use of any monoamine oxidase (MAO) inhibitors (e.g. phenelzine, tranylcypromine), phenothiazines (chlorpromazine) within 30 days prior to first drug administration. 20. Employee or immediate relative of an employee of the investigator, MonoSol Rx LLC, any of its affiliates or partners, or inVentiv Health.