While fibrates can be considered as off-label treatment for PBC that does not respond to UDCA, they should not be used in decompensated cirrhosis.Several additional medications have been investigated as potential treatments for PBC, and found to be ineffective as single agents (monotherapy), including: chlorambucil, colchicine, cyclosporine, corticosteroids, azathioprine, malotilate, methotrexate, mycophenolate mofetil, penicillamine, and thalidomide. Budesonide may be used as an off-label treatment for PBC, although its efficacy is controversial. Itching
Pruritus is a common symptom in people with PBC. First-line treatment of pruritus consists of anion-exchange resins, such as cholestyramine, colestipol, or colesevalam. These anion-exchange resins are nonabsorbed, highly positively charged substances that bind bile acids, which are negatively charged anions. Anion-exchange resins relieve itching caused by excess bile acids in circulation by binding bile acids in the gut and facilitating elimination. Bloating or constipation may occur with anion-exchange resins. Cholestyramine may affect absorption of UDCA; if cholestyramine is necessary, it should be taken at least 60 minutes before or 4 hours after UDCA is taken.Treatment options for pruritus that does not improve with anion-exchange resins include: rifampicin, naltrexone, or sertraline. Rifampicin may rarely cause drug induced liver injury and should be avoided if serum bilirubin is elevated (greater than 2.5 mg/dL). Liver enzymes should be monitored after starting rifampin. Rifampicin induces enzymes, resulting in numerous potential drug-drug interactions. Opioid antagonists may cause a self-limited opioid withdrawal like reaction, with abdominal pain, elevated blood pressure, tachycardia, goose bumps, nightmares, and depersonalization. To avoid such reactions, the dose should start low and gradually be increased.
Other causes include:
Anxiety
Brain tumor
Chronic pains
Concussion – a mild traumatic brain injury
Diabetes
Fibromyalgia
Head injury
Hypercalcemia – too much calcium in the blood
Hypermagnesemia
Hyponatremia – low blood sodium
Hypothyroidism – the body doesnt produce enough hormones that control how cells use energy
Meningitis
Mood disorders – depression
Multiple sclerosis
Narcolepsy – disorder of the nervous system
Skull fractures
Sleeping sickness – caused by a specific parasite
Stress

Medicine
Analgesics – mostly prescribed or illicit opiates such as OxyContin or heroin
Anticonvulsants / antiepileptics – such as phenytoin (Dilantin), carbamazepine (Tegretol), Lyrica (Pregabalin) and Gabapentin
Antidepressants – for instance, sedating tricyclic antidepressants and mirtazapine. Somnolence is less common with SSRIs and SNRIs as well as MAOIs. Antihistamines – for instance, diphenhydramine (Benadryl, Nytol) and doxylamine (Unisom-2)
Antipsychotics – for example, Lurasidone (Latuda), thioridazine, quetiapine (Seroquel), olanzapine (Zyprexa), risperidone and ziprasidone (Geodon) but not haloperidol
Dopamine agonists used in the treatment of Parkinsons disease – e.g. pergolide, ropinirole and pramipexole. HIV medications – such as efavirenz
Hypertension medications – such as amlodipine
Hypnotics, or soporific drugs, commonly known as sleeping pills. Tranquilizers – such as zopiclone (Zimovane), or the benzodiazepines such as diazepam (Valium) or nitrazepam (Mogadon) and the barbiturates, such as amobarbital (Amytal) or secobarbital (Seconal)
Other agents impacting the central nervous system in sufficient or toxic doses

Assessment
Quantifying sleepiness requires a careful assessment. The diagnosis depends on two factors, namely chronicity and reversibility. Chronicity signifies that the patient, unlike healthy people, experiences persistent sleepiness, which does not pass. Reversibility stands for the fact that even if the individual goes to sleep, the sleepiness may not be completely gone after waking up.