Mesilate salts

Phentolamine (Fig. 10.12) is used as its mesilate salt which is freely soluble in water. The use of mesilate salt... 

Benztropine has similar uses and administration to benzhexol. It shares the tropine ring with atropine hut the ester is replaced with an ether and branched benzyl groups. It has some antihistamine and local anaesthetic activity but is not indicated for such uses. Benzatropine (used as the mesilate salt) has a longer half-life than benzhexol and is used as a single daily dose (1-6 mg). It is available in oral (tablet) or injectable (i.m.) dosage forms. 

The mesilate is then formed by addition of methanesulphonic acid. The salt is recrystallized from butanone-2 (s. fig. 10) (2,3,11). 

For inorganic compounds both cation and anion are always mentioned. Abbreviations for the elements are allowed. The EMA now recommends that name and strength of licensed medicines should refer to the active substance or moiety [1]. Therefore in preparations that were licensed by EMA recently, the name and dosing schemes usually refer to the active substance only, even if it is present in a salt form. For instance Pradaxa 75 mg capsules contain dabigatran etexilate mesilate, equivalent to 75 mg dabigatran etexilate. 

In some cases hydrochloride salts are not very water soluble due to the strength of association between the base and its counter ion, and other salts have to be used. For instance, salts may be prepared with di- or tricarboxylic acids, e.g. ergometrine tartrate, diethylcarbamazine citrate, sumatriptan succinate (Fig. 3.18) and lisuride maleate are all used because of the water insolubility of their hydrochlorides. Similarly strong monobasic organic acids such as mesilate are used to promote water solubility, as in the case of benzatropine mesilate (Fig. 3.18) andphentol-amine mesilate. In some instmces salts are too ready to absorb water from the atmosphere, for instance the muscle relaxant dmg atracurium is formulated as its besilate salt to avoid the problems of water absorption experienced with its mesilate. 

Ondansetron has been described as the free base, hydrochloride salt and hydrochloride dihydrate and is available in a variety of formulations. These include hydrochloride tablets (4 and 8 mg) and solutions for injection (2 mg/ mL), oral lyophilisates (4 and 8 mg), sugar-free syrup (4 mg/5 mL as hydrochloride) and suppositories (16 mg). Alosetron hydrochloride tablets (0.5 and 1 mg) are most commonly obtainable. Tropisetron is also available as the hydrochloride salt and comes either as capsules (5 mg) or as a solution for injection at 1 mg/mL. Dolasetron mesilate products are formulated as film-coated tablets (50 and 200 mg) and 20 mg/mL solution for injection. Granisetron is also available as the hydrochloride salt and appears as film-coated tablets (1 and 2 mg) and 1 mg/mL solution for injection and dilution. 

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