Slopes in the lee of a ridge or of another wind obstacle accumulate more snow and are more likely to include pockets of deep snow, wind slabs, and cornices, all of which, when disturbed, may result in avalanche formation. Conversely, the snowpack on a windward slope is often much shallower than on a lee slope. Avalanches and avalanche paths share common elements: a start zone where the avalanche originates, a track along which the avalanche flows, and a runout zone where the avalanche comes to rest. The debris deposit is the accumulated mass of the avalanched snow once it has come to rest in the run-out zone. For the image at left, many small avalanches form in this avalanche path every year, but most of these avalanches do not run the full vertical or horizontal length of the path. The frequency with which avalanches form in a given area is known as the return period. The start zone of an avalanche must be steep enough to allow snow to accelerate once set in motion, additionally convex slopes are less stable than concave slopes, because of the disparity between the tensile strength of snow layers and their compressive strength. The composition and structure of the ground surface beneath the snowpack influences the stability of the snowpack, either being a source of strength or weakness. Avalanches are unlikely to form in very thick forests, but boulders and sparsely distributed vegetation can create weak areas deep within the snowpack through the formation of strong temperature gradients.
History
The synthesis of trospium was described by scientists from Dr. Robert Pfleger Chemische Fabrik GmbH,  Heinz Bertholdt, Robert Pfleger, and Wolfram Schulz, in US. Pat. No. 3,480,626 (the US equivalent to DE119442), and its activity was first published in the literature in 1967.The first regulatory approval was granted in Germany in August 1999 to Madaus AG for Regurin 20 mg Tablets. : 13  Madaus is considered the originator for regulatory filings worldwide. The German filing was recognized throughout Europe under the Mutual Recognition Procedure. : 13 Madaus licensed the US rights to trospium chloride to Interneuron in 1999 and Interneuron ran clinical trials in the US to win FDA approval. Interneuron changed its name to Indevus in 2002 Indevus entered into a partnership with Odyssey Pharmaceuticals, a subsidiary of Pliva, to market the drug in April 2004, and won FDA approval for the drug, which it branded as Sanctura, in May 2004. The approval earned Indevus a milestone payment of $120M from Pliva, which had already paid Indevus $30 million at signing; the market for overactive bladder therapies was estimated to be worth $1.1 billion in 2004. In 2005 Pliva exited the relationship, selling its rights to Esprit Pharma, and in September 2007 Allergan acquired Esprit, and negotiated a new agreement with Indevus under which Allergan would completely take over the US manufacturing, regulatory approvals, and marketing. A month before, Indevus had received FDA approval for an extended release formulation that allowed once a day dosing, Sanctura XR.