Phentermine HCl vs Resin

Since 1959, two organic bases are used for the manufacture of various dosage forms of Phentermine. These bases are ion-exchange resin and hydrochloride (HCl). Depending on the pharmaceutical composition, these weight loss capsules and pills have different properties:
  • Phentermine HCl begins to be absorbed in the esophagus immediately after administration of a tablet or a capsule
  • Phentermine release from the complex with the ion-exchange resin in the digestive tract occurs exclusively under the influence of gastric enzymes
After the intake, Phentermine HCl dissolves rapidly in the patient's esophagus, and reaches a maximum blood concentration in about 3-4 hours after the oral administration. Phentermine resin is absorbed within about 10-14 hours, which contributes to:
  • maintaining a constant therapeutic concentration of the drug in the blood plasma;
  • extension of the maximum clinical effect of this drug for the obesity treatment.
Due to the unique properties of Phentermine resin, it has some advantages over HCl, including:
  • by maintaining a constant drug concentration in the blood after the administration of modified Phentermine release capsules, the risk of side reactions is much lower than after the ingestion of film-coated tablets or capsules;
  • during the use of Phentermine resin, the risk of esophageal irritation is significantly lower, compared to the one you get when you use Phentermine HCl.
The advantage of Phentermine HCl over the resin is the lack of the so-called dose dumping. Immediately after the oral administration of Phentermine resin, a rapid release of high doses takes place within the first hours, which increases the risk of adverse reactions at the beginning of its use.