Encapsulation of drugs and excipients in liposomes — measurements with drug-specific electrodes

• Published in: Pharmaceutica acta Helvetiae Vol. 68; no. 2; pp. 129 - 133
• Main Authors: Gücer, N., Ebel, J., Gröning, R.
• Format: Journal Article
• Language: English
• Published: Amsterdam Elsevier B.V 01.09.1993; Elsevier
• Subjects: Benzalkonium Compounds - chemistry; Biological and medical sciences; Chemistry, Pharmaceutical; Drug Carriers - chemistry; Drug Compounding; Electrodes; Encapsulation; Excipients; General pharmacology; Liposome; Liposomes - chemistry; Medical sciences; Membrane electrode; Pharmaceutical technology. Pharmaceutical industry; Pharmacology. Drug treatments; Encapsulation; Liposome; Membrane electrode; Ion selective electrode; Pharmaceutical technology; Drug targeting; Measurement method; Potentiometry
• ISSN: 0031-6865
• DOI: 10.1016/0031-6865(93)90015-X

In this study, the degree of encapsulation of benzalkonium chloride in liposomes was quantitatively measured using a potentiometric membrane electrode specific for benzalkonium chloride. The encapsulation of lidocaine hydrochloride was examined with another ion-selective electrode for comparison. Liposomes were prepared from a commercially available liposome concentrate (Phosal 75 SA). Photon correlation spectroscopy was used to detect the formation of liposomes in the size range of 200 nm. The measurements with the membrane electrode enabled the activity of the free drug to be quantitatively determined in the presence of liposomes. The investigations showed that, in the concentration range examined, up to 97% of the amphiphilic benzalkonium chloride is encapsulated in the liposomes. In the case of the hydrophilic lidocaine hydrochloride, virtually no liposomal encapsulation occurs.