Claims
- 1. A process for preparing the higher-melting polymorph of terfenadine which comprises dissolving terfenadine in a water-miscible, lower alkanol, heating the solution at about its reflux temperature, slowly adding a sufficient quantity of water with stirring to effect substantial crystallization of terfenadine, cooling, and collecting the crystalline product.
- 2. A process according to claim 1 wherein the water-miscible, lower alkanol is methanol, ethanol or isopropanol.
- 3. A process according to claim 1 wherein the water-miscible, lower alkanol is ethanol.
- 4. A process according to claim 1 wherein the weight to volume ratio of terfenadine to ethanol in the solution is from 0.1 g/ml to 0.3 g/ml.
- 5. A process according to claim 3 wherein the volume to volume ratio of ethanol to water is about 0.75 ml/ml to 1.5 ml/ml.
- 6. A process according to claim 3 wherein the volume to volume ratio of ethanol to water is about 1.0 ml/ml.
- 7. A process according to claim 3 wherein the temperature of the solution of terfenadine in ethanol is about 78.degree. C.
- 8. A process according to claim 1 wherein a solution of terfenadine in ethanol, having a weight to volume ratio of terfenadine to ethanol of about 0.15 to 0.25 is heated to 78.degree. C., sufficient water to result in a volume to volume ratio of ethanol to water of about 1 ml/ml was added over about 30 minutes, the resulting slurry was heated at its reflux temperature for from 0 to 5 hours, cooled slowly to room temperature, then cooled to from 0.degree. C. to 5.degree. C., filtered and the recovered terfenadine dried.
- 9. A process for preparing the lower-melting polymorph of terfenadine which comprises dissolving terfenadine in a suitable solvent at about 0.degree. C. to about 35.degree. C., allowing the solvent to slowly evaporate and collecting the crystalline product.
- 10. A process according to claim 9 wherein the solvent is acetone.
- 11. A process according to claim 9 wherein the solvent is toluene.
CROSS REFERENCE TO RELATED APPLICATION
This is a continuation of application Ser. No. 860,619, filed May 7, 1986, now abandoned.
US Referenced Citations (1)
Number |
Name |
Date |
Kind |
3878217 |
Carr et al. |
Apr 1975 |
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Continuations (1)
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Number |
Date |
Country |
Parent |
860619 |
May 1986 |
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