Due to the mainly hepatic elimination,  no risk of accumulation exists in people with renal impairment.One of the major active metabolites of buprenorphine is norbuprenorphine, which, in contrast to buprenorphine itself, is a full agonist of the MOR, DOR, and ORL-1, and a partial agonist at the KOR. However, relative to buprenorphine, norbuprenorphine has extremely little antinociceptive potency (1/50th that of buprenorphine), but markedly depresses respiration (10-fold more than buprenorphine). This may be explained by very poor brain penetration of norbuprenorphine due to a high affinity of the compound for P-glycoprotein. In contrast to norbuprenorphine, buprenorphine and its glucuronide metabolites are negligibly transported by P-glycoprotein.The glucuronides of buprenorphine and norbuprenorphine are also biologically active, and represent major active metabolites of buprenorphine. Buprenorphine-3-glucuronide has affinity for the MOR (Ki = 4.9 pM), DOR (Ki = 270 nM) and ORL-1 (Ki = 36 μM), and no affinity for the KOR. It has a small antinociceptive effect and no effect on respiration. Norbuprenorphine-3-glucuronide has no affinity for the MOR or DOR, but does bind to the KOR (Ki = 300 nM) and ORL-1 (Ki = 18 μM). It has a sedative effect but no effect on respiration. Chemistry
Buprenorphine is a semisynthetic derivative of thebaine, and is fairly soluble in water, as its hydrochloride salt. It degrades in the presence of light. Detection in body fluids
Buprenorphine and norbuprenorphine may be quantified in blood or urine to monitor use or non-medical recreational use, confirm a diagnosis of poisoning, or assist in a medicolegal investigation.
Nephroptosis,  is rare and abnormal condition in which the kidney drops down into the pelvis when the patient stands up. It is more common in women than in men. It has been one of the most controversial conditions in terms of both its diagnosis and its treatments. Symptoms and signs
Nephroptosis is asymptomatic in most persons. However, nephroptosis can be characterized by violent attacks of colicky flank pain, nausea, chills, hypertension, hematuria and proteinuria. Persons with symptomatic nephroptosis often complain of sharp pains that radiate into the groin. Many persons also suggest a weighing feeling on the abdomen. Pain is typically relieved by lying down. It is believed that flank pain on standing that is relieved by lying down is due to movement of the kidney causing intermittent renal tract obstruction. The attack of colic pain is called Dietls crisis or renal paroxysm. Cause
It is believed to result from deficiency of supporting inferior pararenal fasciae. Diagnosis
Diagnosis is contemplated based upon patient symptoms. Diagnosis is confirmed during intravenous urography, by obtaining erect and supine films. The renal DMSA scan may show decreased counts in the sitting position compared with supine scan. Treatment
Nephropexy was performed in the past to stabilize the kidney, but presently surgery is not recommended in asymptomatic patients. A Nephropexy does not guarantee the symptoms will go away. Laparoscopic nephropexy has recently become available for selected symptomatic patients. References
Further reading
Barber N, Thompson P (2004). "Nephroptosis and nephropexy--hung up on the past?". Eur Urol. 46 (4): 428–33. doi:10.1016/j.eururo.2004.03.023. PMID 15363554. == External links ==