Lonafarnib With and Without Ritonavir in HDV (LOWR-1)

To Evaluate the Safety and Efficacy of Lonafarnib with and without Ritonavir Boosting in Adults With Genotype 1 Chronic Hepatitis D Virus (HDV) Infection (LOWR-1).

Inclusion Criteria: * Males or females, 18 to 65 years of age who are diagnosed with HDV by PCR * Chronic hepatitis D infection, genotype 1, documented by a positive anti-HDV Ab test at least of 6 months duration and detectable HDV RNA by PCR within 3 months to study entry * Liver biopsy within the last two years * Positive viral load by quantitative PCR * Electrocardiogram (ECG) shows no acute ischemia or clinically significant abnormality and a QT/QTc interval \ 20 g per day for females (1.5 standard alcohol drinks) or \> 30 g per day for males (2.0 standard alcohol drinks) (a standard drink contains 14 g of alcohol: 12 oz of beer, 5 oz of wine or 1.5 oz of spirits) (1.0 fluid oz (US) = 29.57 mL). * Drug abuse within the last six months with the exception of cannabinoids and their derivatives * Patients with absolute neutrophil count (ANC) \< 1500 cells/mm\^3; platelet count \< 100,000 cells/mm\^3; hemoglobin \< 12 g/dL for women and \< 13 g/dL for men; abnormal TSH,T4, or T3 or thyroid function not adequately controlled; or serum creatinine concentration ≥ 1.5 times upper limit of normal (ULN) * History or clinical evidence of any of the following: 1. variceal bleeding, ascites, hepatic encephalopathy, CTP score \> 6, decompensated liver disease or any other form of non-viral hepatitis 2. immunologically mediated disease (e.g., rheumatoid arthritis, inflammatory bowel disease, severe psoriasis, systemic lupus erythematosus) requiring more than intermittent nonsteroidal anti-inflammatory medications for management or that requires frequent or prolonged use of corticosteroids (inhaled asthma medications are allowed) 3. any malignancy within 3 years except for basal cell skin cancer 4. significant or unstable cardiac disease (e.g., angina, congestive heart failure, uncontrolled hypertension, history of arrhythmia) 5. chronic pulmonary disease (e.g., chronic obstructive pulmonary disease) associated with functional impairment 6. severe or uncontrolled psychiatric disease, including severe depression, history of suicidal ideation, suicidal attempts or psychosis requiring medication and/or hospitalization 2 * Patients with a body mass index \> 30 kg/m\^2 * Concomitant drugs known to prolong the QT interval