GB1569746A - Indole derivatives - Google Patents

Description

(54) INDOLE DERIVATIVES (71) We, JOHN WYETH & BROTHER LIMITED, a British Company of Huntercombe Lane South, Taplow, Maidenhead, Berkshire SL6 OPH, do hereby declare the invention for which we pray that a patent may be granted to us and the method by which it is to be performed, to be particularly described in and by the following statement: This invention relates to indole derivatives.

In our UK Patent Specification No. 1218570 we have described and claimed a class of indole derivatives which have various pharmacological activities, especially action on the cardiovascular system. One of these compounds 3-[2(4- benzamido-l piperidyl)ethyl] indole has demonstrated valuable anti-hypertensive properties in human beings as shown in clinical trials. This compound, which has the international approved name, indoramin, is generally used in the form of its hydrochloride salt. Certain clinical investigations have shown the need for a more soluble salt of indoramin. We have now discovered novel salts which possess substantially greater solubility in water than the hydrochloride.

Accordingly the invention provides the lower alkyl sulphonate salts of 3-[2 < 4-benza- mido-l -piperidyl)ethyl] indole, in which the lower alkyl group has from 1 to 6 carbon atoms.

The preferred salt of the invention is the methane suiphonate which is approximately five times as soluble as the hydrochloride.

The salts of the invention are prepared by mixing the indoramin base with the appropriate lower alkylsulphonic acid in a suitable solvent, e.g. a lower alkanol such as ethanol. The lower alkyl sulphonic acid may be methane, ethane, propane, butane, pentane, or hexane sulphonic acid. Preferably the lower alkyl group has from 1 to 4 carbon atoms.

The salts of the invention may be used in pharmaceutical compositions comprising the indoramin lower alkyl sulphonate salt and a pharmaceutically acceptable carrier. Suitable carriers are well known in the art. The carrier may be a solid or liquid. The particular dosage will depend on the chosen route of administration and standard pharmaceutical practice.

The compounds of the invention may be used in unit dosage form, e.g. tablets or capsules.

The following examples illustrate the invention: EXAMPLE 1 3-[2+4-Benzamido-1-piperidyl)ethyl] indole, methane sulphonate A suspension of 3-[2-(4-benzamido-1 -piper- idyl)ethyl] indole (3 5g) in warm ethanol (30cm) was acidified with methane sulphonic acid, the solid dissolved to give a clear solution which was diluted with ethyl acetate (20cm3) and cooled in ice. The precipitated product was - collected by filtration and crystallised from methanol to give the title compound (3.lug, 70to) m.p. 224-50C.

Found: C, 61.98;H, 6.54; N, 9.54.C22H25N3 O.CH403S requires C, 62.29;H, 6.59;N, 9.48.

The title compound had a solubility in water > 10 mg/ml at 20"C.

EXAMPLE 2 3-[2-(4-Benzamido-l -piperidyl)ethyl] indole, n-propane sulphonate Following the procedure of Example 1 but using n-propane sulphonic acid instead of methane sulphonic acid the title compound is prepared.

WHAT WE CLAIM IS: 1. A lower alkylsulphonate salt of 3-[2 < 4- benzamido-l -piperidyl)ethyl] indole.

2. A salt as claimed in claim 1, wherein the lower alkyl group has from 1 to 4 carbon atoms.

3. The methane sulphonate salt of 3-[2-(4 benzamido-l -piperidyl)ethyl] indole.

4. A pharmaceutical composition comprising a lower alkylsulphonate salt as claimed in any one of claims 1 to 3 and a pharmaceutically acceptable carrier.

5. A pharmaceutical composition as claimed in claim 4, in unit dosage form.

6. A lower alkyl sulphonate salt substantially as hereinbefore described in Example 1.

**WARNING** end of DESC field may overlap start of CLMS **.

Claims (6)

**WARNING** start of CLMS field may overlap end of DESC **. methane sulphonic acid the title compound is prepared. WHAT WE CLAIM IS:

1. A lower alkylsulphonate salt of 3-[2 < 4- benzamido-l -piperidyl)ethyl] indole.

2. A salt as claimed in claim 1, wherein the lower alkyl group has from 1 to 4 carbon atoms.

3. The methane sulphonate salt of 3-[2-(4 benzamido-l -piperidyl)ethyl] indole.

4. A pharmaceutical composition comprising a lower alkylsulphonate salt as claimed in any one of claims 1 to 3 and a pharmaceutically acceptable carrier.

5. A pharmaceutical composition as claimed in claim 4, in unit dosage form.

6. A lower alkyl sulphonate salt substantially as hereinbefore described in Example 1.