Chemistry
Gemcitabine is a synthetic pyrimidine nucleoside prodrug—a nucleoside analog in which the hydrogen atoms on the 2 carbon of deoxycytidine are replaced by fluorine atoms.The synthesis described and pictured below is the original synthesis done in the Eli Lilly Company labs. Synthesis begins with enantiopure D-glyceraldehyde (R)-2 as the starting material which can made from D-mannitol in 2–7 steps. Then fluorine is introduced by a "building block" approach using ethyl bromodifluroacetate. Then, Reformatsky reaction under standard conditions will yield a 3:1 anti/syn diastereomeric mixture, with one major product. Separation of the diastereomers is carried out via HPLC, thus yielding the anti-3 gemcitabine in a 65% yield. At least two other full synthesis methods have also been developed by different groups. History
Gemcitabine was first synthesized in Larry Hertels lab at Eli Lilly and Company during the early 1980s. It was intended as an antiviral drug, but preclinical testing showed that it killed leukemia cells in vitro.During the early 1990s gemcitabine was studied in clinical trials. The pancreatic cancer trials found that gemcitabine increased one-year survival time significantly, and it was approved in the UK in 1995 and approved by the FDA in 1996 for pancreatic cancers. In 1998, gemcitabine received FDA approval for treating non-small cell lung cancer and in 2004, it was approved for metastatic breast cancer.European labels were harmonized by the EMA in 2008.By 2008, Lillys worldwide sales of gemcitabine were about $1.7 billion; at that time its US patents were set to expire in 2013 and its European patents in 2009.
A cholinergic crisis is an over-stimulation at a neuromuscular junction due to an excess of acetylcholine (ACh), as a result of the inactivity of the AChE enzyme, which normally breaks down acetylcholine. Symptoms and diagnosis
As a result of cholinergic crisis, the muscles stop responding to the high synaptic levels of ACh, leading to flaccid paralysis, respiratory failure, and other signs and symptoms reminiscent of organophosphate poisoning. Other symptoms include increased sweating, salivation, bronchial secretions along with miosis (constricted pupils). This crisis may be masked by the concomitant use of atropine along with cholinesterase inhibitor medication in order to prevent side effects. Flaccid paralysis resulting from cholinergic crisis can be distinguished from myasthenia gravis by the use of the drug edrophonium (Tensilon), as it only worsens the paralysis caused by cholinergic crisis but strengthens the muscle response in the case of myasthenia gravis. (Edrophonium is a cholinesterase inhibitor, hence increases the concentration of acetylcholine present).