Physico-chemical properties of a modified biomaterial from <i>Tympanotonus fuscata</i> (periwinkle) shell powder considered as pharmaceutical excipient

Abstract

A modified biomaterial developed from Tympanotonus fuscata shell was characterized, for possible use as a pharmaceutical excipient. A 100 g quantity of pulverized periwinkle shell was digested in 166 ml of 2 M HCl, filtered and neutralized with 5 M NaOH. The precipitate obtained was washed severally with deionized water. Ortho-phosphoric acid was added drop wise to its thick aqueous suspension until a thick, dehydrated mass forms which was blended for 5 min and dried at 60 ^o C. It was classified with 250 μm sieve to obtain a modified biomaterial powder of periwinkle shell (MBPPS). This was tested for calcium and phosphate compound, solubility, pH, moisture absorption, acute toxicity, elemental content, drug compatibility, ash values, densities, flow parameters, etc. MBPPS was a compactable white powder, non-toxic (LD ₅₀ >> 15,000 mg / kg body), tasteless, odourless, melting temperature, 190.8^oC, tested positive for calcium and phosphate compound and was compatible with a range of drugs. It was soluble in dilute HCl and HNO₃ but practically insoluble in cold water and organic solvents. Its 10 % w/v aqueous dispersion has pH of 7.57. Whereas, lead, silver, cadmium, nickel, vanadium, mercury or barium were not detected, iron and some heavy metals were detected, though their levels were within pharmacopoeial limit. MBPPS contained 2.28 ± 0.01 % moisture. It absorbed 6.98 ± 0.15, 9.08 ± 0.28 & 11.00 ± 0.87 % moisture in relative humidities of 96, 84, 75 and 52 % at 30 ^o C respectively. Total ash of 88.00 ± 1.30%, acid insoluble ash, 0.6 ± 0.24 % and water soluble ash, 0.5 ± 0.06 % were obtained. Considering the high yield of MBPPS, its non-toxicity, compatibility with a range of drugs, and hardness above 12 N of its compact, it may serve as a good material for direct compression of tablets especially for low dose drugs.

Key words: Physicochemical properties, modified, biomaterial, Tympanotonus fuscata, periwinkle shell, pharmaceutical excipient