ABSTRACT
A fourteen years old Malay boy was involved in a motor vehicle accident and suffered multiple injuries. The patient was referred to ophthalmology for right periorbital haematoma, ocular examination was normal but proptosis of right eye was detected which was later associated with increase in the intraocular pressure (IOP). Direct carotid cavernous sinus fistula (CCF) was diagnosed by angiography and treated with embolization.
ABSTRACT
The present study was directed to optimize the stability of melanin liposomes utilizing the technique of lyophilization. Two types of cryoprotectants; sucrose and lactose, each in two concentrations of 5% and 10% were used. Lyophilized liposomes [10% lactose] either fresh or stored for one year at 5°C showed no significant changes [P>0.05] in the phase transition temperatures [Tc], structure and shape, and size distribution of the fresh unlyophilized liposomes. The fresh unlyophilized liposomes were unilamellar with Tc of 41.6°C and an average size of 5.21 micro m. The stored unlyophilized liposomes showed a significant [P<0.05] decrease in Tc [32.8°C] and increase in the average size [15.6 micro m] with the formation of onion- like multilamellar vesicles compared with the fresh unlyophilized ones. Lyophilization of melanin liposomes with different cryoprotectants significantly [P<0.001] decreased the rate of leakage of entrapped melanin from the liposomal structure compared with the unlyophilized ones. This cryoprotection effect was significantly [P<0.05] increased by the use of lactose and by increasing the cryoprotectant concentration. The entrapped melanin in lyophilized liposomes with 10% lactose was chemically stable for six months at 5°C as evaluated by mass spectroscopic analysis. As a conclusion, lyophilization with 10% lactose maintained the chemical stability of melanin and significantly improved the physical stability of melanin liposomes
Subject(s)
Melanins , Liposomes , Cryoprotective Agents/pharmacology , Drug Carriers , Spectrum AnalysisABSTRACT
The effect of polyethylene glycols 400, 1500 and 4000 on the rheological characteristics of Macaloid dispersions was studied. The rheological study included investigation of the phenomena of consistency, thixotropic breakdown and structural recovery in the stationary state. The consistency of Macaloid dispersions increases in presence of PEG 400 and PEG 1500. This increase is, generally, in direct proportion to the glycol concentration. In the case of PEG 4000, the consistency of Macaloid dispersions is slightly decreased in presence of the low concentrations of the glycol and is slightly affected at the high ones. These effects were interpreted as sum of the adsorption of the glycols between the clay lamellae, the thickening effect of the glycols towards the continuous phase of the dispersions and the dehydrating effect of the glycols. The rate of increase consistency of Macaloid dispersions, on aging is generally increased in presence of low concentrations of the glycols which might indicate a slow adsorption of the glycols. This rate is, however, decreased at high glycol concentrations, which might be a result of the dehydrating effect of the glycols. The thixotropic breakdown of Macaloid dispersions, induced by increasing rate of shear, is generally increased in presence of PEG 400 and PEG 1500 and decreased by PEG 4000. On the other hand, the thixotropic breakdown by shearing is affected differently by the different concentrations of the glycols. The rate of structural recovery is affected differently by the different concentrations of polyethylene glycols. However, all systems attain complete structural recovery after a rest of an hour
Subject(s)
Polyethylene Glycols/pharmacokinetics , Rheology , Polyethylene GlycolsABSTRACT
It was found that the hydrotropic agents enhance the water-solubility of carbamazepine as a function of their concentration. The solubilizing power of these hydrotropes was shown to be highly dependent on their chemical structure. The solubilizing power of the amino derivatives is generally higher than that of the hydroxy derivatives. The position of the hydroxyl or amino groups relevant to the carboxylate group in the hydrotrope molecule plays a major role in its solubilizing effect. The spectral pattern of carbamazepine was found to undergo a change in presence of these compounds. Applying the continuous variation method revealed formation of 2:1 carbamazepine complex with each of sodium salicylate and sodium anthranilate as well as a 1:2 complex with sodium p-amino benzoate. Also, the drug forms 1:1 complexes with both sodium m-hydroxybenzoate and sodium p-hydroxybenzoate. On the other hand, two species of complexes appear to be formed in carbamazepine-sodium p- aminosalicylate system, viz., 1:2 and 2:1 complexes. An apparent correlation seems to exist between the solubilizing power of the investigated hydrotropes and the stability constant of their respective complexes with the drug. Calculating the amount of drug solubilized in free as well as in complexed forms in these systems revealed that the decrease in the activity coefficient of carbamazepine in presence of the investigated hydrotropes may be responsible for the increase in carbamazepine solubility beside complex-formation
Subject(s)
AminobenzoatesABSTRACT
The effect of nicotinamide and sodium benzoate, naphthoate and nicotinate on the solubility of carbamazepine in water was studied. The investigated hydrotropes were found to increase the solubility of carbamazepine. The solubilizing power of these hydrotropes was shown to be highly dependent on their chemical structure. The replacement of benzene ring by a naphthalene or pyridine ring enhances solubilization. Molecular interaction of carbamazepine with the investigated solubilizers was depicted via differential ultraviolet spectrophotometric measurements. Applying the continuous variation method revealed formation of 1:1 complex with sodium nicotinate, 2:1 complex with nicotinamide and sodium naphthoate and a mixture of 2:1 and 1:2 complexes with sodium benzoate. An apparent correlation seems to exist between the solubilizing power of these hydrotropic agents and the stability constant of their respective complexes. Calculating the amount of drug solubilized in free as well as complexed forms revealed that complex-formation as well as the decrease in activity coefficient of the drug are the two factors governing the hydrotropic behavior of these compounds towards carbamazepine