1. Research on Combinations of Substances,
Found in Latvia, and their Possible Compatibility
in Extemporaneous Dosage Forms for Dermatology
22904
Olga Kiseļova, Rīga Stradiņš University
Baiba Mauriņa, Rīga Stradiņš University
Venta Šidlovska, Rīga Stradiņš University
Introduction
Compatibility of 3 combinations of active substances in different mediums for suspensions
Extemporaneous compounding is defined as the preparation, mixing, assembling, packaging and labeling of a medicinal product based on a prescription order from a licensed practitioner for the individual patient. More than half of Latvian pharmacies (411 out of 764) have a license for preparation of medicinal products in a pharmacy. Latvia does not have any standards for compounding of extemporaneous prescriptions. There is no clear picture on combinations of most commonly prescribed active substances, excipients, dosage forms. In the earlier studies, authors found that dermatovenerologists prescribed extemporaneous compositions most often.
Combination
Medium
Sulfur
and
Salicylic Acid
Boric Acid
Menthol
Purified water -
Ethanol (900) +
Glycerol
Vegetable oil
Purified water with Ethanol (900)
Purified water with Glycerol
Purified water with Ethanol (900) and Glycerol
Aim of the project
To explore a compatibility of drug substances used in extemporaneous compositions in Latvia, in the extemporaneous dosage forms prescribed by dermatovenerologists.
For analysis of ointments were used soft paraffin, soft paraffin with wool fat, vegetable oil in a combination with wool fat and purified water.
It depends on ointment bases whether active substances will be absorbed by the skin or not.
Materials and methods
Exploring extemporaneous compositions there was created a database with prescriptions, compounded in Latvian pharmacies during Since the pharmaceutical compatibility or incompatibility of active substances is linked to a particular dosage form, then in the study there were analysed dosage forms which are the most common in dermatovenerologists’ prescriptions – suspensions and ointments.
Compatibility of 3 combinations of active substances in different bases for ointments
Combination
Bases
Sulfur
and
Salicylic Acid
Boric Acid
Menthol
Soft paraffin + -
Soft paraffin with wool fat
Vegetable oil with wool fat and purified water
Results
There were identified the most commonly prescribed active substances and excipients, as well as combinations of active substances in suspensions and ointments.
For analysis authors selected 3 most common combinations of active substances – sulfur with salicylic acid, sulfur with boric acid, sulfur with menthol.
Compatibility was analysed guiding by physical properties of active substances and excipients.
The suspension medium has the leading role in a compatibility or incompatibility of active substances in a dosage form, as there must be a sufficient contact between medium and phase, in order the suspension would be in a good quality.
For analysis of suspensions were used purified water, ethanol (90 per cent), glycerol, vegetable oil and their combinations.
Conclusions
The compatibility or incompatibility of active substances depends on physical features of the substances, dosage form, excipients.
The same combination of active substances may be compatible in one medium and incompatible in another.
The cooperation between a physician and pharmacist in the extemporaneous drug compounding procedure is significant for prevention of possible incompatibility and satisfaction of a patient’s needs.