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Photon correlation spectroscopy of surface active cationic drugs.
The Journal of Pharmacy and Pharmacology
|December 1, 1985
Summary
Antidepressant and antihistamine drugs form micelles in solution. Photon correlation spectroscopy revealed that antidepressants generally form the largest micelles, suggesting a stacking aggregation mechanism similar to phenothiazines.
Area of Science:
- Pharmaceutical Chemistry
- Physical Chemistry
- Materials Science
Background:
- Antidepressant and antihistamine drugs are widely used, but their aggregation behavior in solution is not fully understood.
- Understanding drug aggregation is crucial for formulation, delivery, and predicting potential interactions.
- Previous studies have explored micelle formation in drug solutions, but a systematic investigation across various drug classes is needed.
Purpose of the Study:
- To investigate the aggregation behavior of various antidepressant and antihistamine drugs in aqueous NaCl solutions.
- To determine critical micelle concentrations (CMCs) and micellar sizes for these drugs.
- To elucidate the relationship between drug structure, concentration, and micellar properties.
Main Methods:
- Photon Correlation Spectroscopy (PCS) was employed to measure micellar sizes and aggregation dynamics.
- Surface tension measurements were used to determine critical micelle concentrations (CMCs).
- A series of antidepressant and antihistamine drugs, including imipramine, amitriptyline, and diphenhydramine, were studied in varying NaCl concentrations.
Main Results:
- Critical micelle concentrations (CMCs) were successfully measured for all studied drugs using both PCS and surface tension methods.
- Micellar sizes were found to be dependent on drug structure, drug concentration, and NaCl concentration.
- Antidepressant drugs, in general, formed significantly larger micelles compared to antihistamine drugs.
Conclusions:
- The study demonstrates that antidepressants and antihistamines can form micelles in aqueous NaCl solutions.
- A proposed aggregation model suggests that antidepressants aggregate via stacking, similar to phenothiazines, with micellar size increasing through monomer addition and aggregate growth.
- These findings provide valuable insights into the physical chemistry of drug aggregation, relevant for pharmaceutical development and formulation.