In accordance with its low DAT occupancy, no measurable dopamine release in the human brain was detected with bupropion (one 150 mg dose) in a PET study. These findings raise questions about the role of dopamine reuptake inhibition in the pharmacology of bupropion, and suggest that other actions may be responsible for its therapeutic effects. More research is needed in this area. No data are available on occupancy of the norepinephrine transporter (NET) by bupropion and its metabolites. However, due to the increased exposure of hydroxybupropion over bupropion itself, which has higher affinity for the NET than the DAT, bupropions overall pharmacological profile in humans may end up making it effectively more of a norepinephrine reuptake inhibitor than a dopamine reuptake inhibitor. Accordingly, the clinical effects of bupropion are more consistent with noradrenergic activity than with dopaminergic actions. Pharmacokinetics
After oral administration, bupropion is rapidly and completely absorbed reaching the peak blood plasma concentration after 1.5 hours (tmax). Sustained release (SR) and extended release (XL) formulations have been designed to slow down absorption resulting in tmax of 3 hours and 5 hours, respectively. Absolute bioavailability of bupropion is unknown but is presumed to be low, at 5–20%, due to the first-pass metabolism. As for the relative biovailability of the formulations, XL formulation has lower bioavailability (68%) compared to SR formulation and immediate release bupropion.Bupropion is metabolized in the body by a variety of pathways. The oxidative pathways are by cytochrome P450 isoenzymes CYP2B6 leading to R,R- and S,S-hydroxybupropion and, to a lesser degree, CYP2C19 leading to 4-hydroxybupropion.
Lymphomatoid granulomatosis (LYG or LG) is a very rare lymphoproliferative disorder first characterized in 1972. Lymphomatoid means lymphoma-like and  granulomatosis denotes the microscopic characteristic of the presence of granulomas with polymorphic lymphoid infiltrates and focal necrosis within it. LG most commonly affects middle aged people, but has occasionally been observed in young people. Males are found to be affected twice as often as females. Causes
Lymphomatoid granulomatosis involves malignant B cells and reactive, non-malignant T cells and is almost always associated with infection of the malignant B cells by the Epstein-Barr virus; it is therefore considered to be a form of the Epstein-Barr virus-associated lymphoproliferative diseases. The disease is believed to be induced by a combination of Epstein Barr virus infection and immunosuppression through immunosuppressive drugs (with case reports of methotrexate and azathioprine), infections such as HIV or chronic viral hepatitis or endogenous T cell defects. Pathophysiology
The onset of the disease results in proliferation of EBV-infected malignant B-cells and a cytotoxic T-cell response which in turn leads to organ infiltration and dysfunction of the affected organs. The disease typically always relapse after successful treatment due to inability of the immune system and current viral drugs to eliminate an EBV-infection. If the onset of the disease can be linked to use of immunosuppressive drugs then discontinuation of these drugs may hinder a relapse. Organs usually affected are the skin, lungs, central nervous system while liver and kidney are affected to lesser extent.