Levorphanol prodrugs and processes for making and using them

A method of treating pain in a patient in need thereof, the method comprising the step of:

• Administering to the patient in need thereof a composition comprising a therapeutically effective amount of a compound having a structure of Formula I:
• where L is absent, or is
• Y is absent, or [A-X—Z]n
• where A, X, Z are independently absent or selected from —O—, —S— or —(CR1R2)k—
• R1, R2 are each independently selected from H, alkyl, aryl, alkylaryl, alkoxy, haloalkyl, haloaryl
• n and k are independently 1-4
• Gm is absent or selected independently for each repeating subunit from H, oxoacid, polyethylene glycol having from 2 to 5 ethylene oxide units, or a vitamin compound, and m is 1-4, except m is 1 when G is H;
• or a pharmaceutically acceptable salt thereof.

The method of claim 131, wherein the pharmaceutically acceptable salt is selected from the group consisting of acetate, 1-aspartate, besylate, bicarbonate, carbonate, d-camsylate, l-camsylate, citrate, edisylate, formate, fumarate, gluconate, hydrobromide/bromide, hydrochloride/chloride, d-lactate, 1-lactate, d,l-lactate, d,l-malate, 1-malate, mesylate, pamoate, phosphate, succinate, sulfate, bisulfate, d-tartrate, l-tartrate, d,l-tartrate, meso-tartrate, benzoate, gluceptate, d-glucuronate, hybenzate, isethionate, malonate, methylsulfate, 2-napsylate, nicotinate, nitrate, orotate, stearate, tosylate, thiocyanate, acefyllinate, aceturate, aminosalicylate, ascorbate, borate, butyrate, camphorate, camphocarbonate, decanoate, hexanoate, cholate, cypionate, dichloroacetate, edentate, ethyl sulfate, furate, fusidate, galactarate (mucate), galacturonate, gallate, gentisate, glutamate, glutarate, glycerophosphate, heptanoate (enanthate), hydroxybenzoate, hippurate, phenylpropionate, iodide, xinafoate, lactobionate, laurate, maleate, mandelate, methanesulfonate, myristate, napadisilate, oleate, oxalate, palmitate, picrate, pivalate, propionate, pyrophosphate, salicylate, salicylsulfate, sulfosalicylate, tannate, terephthalate, thiosalicylate, tribrophenate, valerate, valproate, adipate, 4-acetamidobenzoate, camsylate, octanoate, estolate, esylate, glycolate, thiocyanate, or undecylenate.