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A note on stability of emulsions and evaluation.

Stability of Emulsions and Evaluation of Stability 1) Stability of Emulsions There are two principal requirements for the stability of an emulsion : i) There should not be changes in mean droplet size and size distribution of the droplets in an emulsion. ii) The suspended droplets should remain homogeneously dispersed in the continuous phase throughout it's shelf life. Stability/ instability of the emulsions can be seen by observing following phenomenon: a) Flocculation : It is the aggregation or clumping of dispersed droplets. This aggregation is re-dispersible by shaking. As the aggregates form due to electrical charges on the droplets/ globules where interfacial film remains intact, flocculation is reversible. Sometimes, flocculation further results into coalescence where the number of globules come together and form a large globule (interfacial film breaks). b) Creaming : In o/w emulsion, dispersed oil globules migrate at the top and accumulate, whereas in w/o emulsion, d

CAPSULES I

Capsules are solid unit dosage forms in which the drug substance is enclosed within either a hard or soft gelatin shell. Hard gelatin capsules (HGC) : Hard Gelatin Capsules Contain two parts: a cap and other is a body. Widely used for the filling of powders, granules and pellets. Manufactured by dipping method, which involves steps: Dipping, Rotation, Drying, Stripping, Trimming & Joining . These are less plasticised than soft gelatin capsules. Soft gelatin capsules ( SGC): Soft Gelatin Capsules (Softgels) Referred as softgels as these are made from the more plasticised gelatin film. These are completely sealed dosage form & cannot be opened without destroying the shell. Generally, suspensions or the solutions of drug that do not solubilize the gelatin shell are enclosed in SGC. The most common methods for preparation of SGC is Rotary die process, Plate process, Bubble method, Accogel (powder or granules filling). HARD GELATIN CAPSULES (

Linctuses: Monophasic Liquid Dosage Form

LINCTUSES What is a Linctus? Linctuses are sweet, viscous liquid oral preparations containing medicinal substances which have demulscent, expectorant or sedative properties. These contain high proportions of syrup and glycerin which exert demulscent effect on the mucous membrane of throat. In order to obtain prolonged local action, linctuses should be administered slowly in undiluted form. Formulation of Linctus 1. Vehicle : Syrups are mostly used as vehicles in the linctuses. Tolu syrup is preferred in cough preparations due to its aromatic odor and flavour. Glycerol syrup and invert syrup are also used as vehicles. Linctus preparation for diabetic patients contain sorbitol syrup (vehicle). Medicament is first dissolved in little amount of water and then added into vehicle. Syrups are viscous and contain less amount of water, this limits (affects) the dissolution of medicament in syrup. 2. Additives: Colouring agents : Amaranth, Erythrosin, Tartrazine. Flavouring agents : Lemon syr

EVALUATION PARAMETERS OF TABLETS

Evaluation of tablets Notes on tablets II Tablets are evaluated for their physical, chemical and bioavailability properties. Stability testing is also an important evaluation parameter. Theset are divided into official and unofficial tests. Unofficial tests : 1. Appearance 2. Size and shape 3. Organoleptic properties (color, odor, taste) 4. Hardness 5. Friability Official tests : 1. Drug content 2. Weight variation 3. Disintegration 4. Dissolution Let's see important parameters in all the test (from GPAT point of view): Measurement of crown thickness : Instruments used are Micrometer and Caliper scale . Tablet thickness values variations: ±5% variation of a std value. Instruments used for color evaluation : Reflectance spectrophotometry Tristimulus colorimetric measurements Microreflectance photometer (measure the color uniformity and gloss on a tablet surface) Hardness and Friability Hardness : tablet crushing str

Details on Affinity Chromatography- download [pdf] and [ppt]

Affinity chromatography Affinity chromatography is a method of separating biochemical mixture based on a highly specific interaction between antigen and antibody , enzyme and substrate , receptor and ligand , or protein and nucleic acid . Back in the year of post-graduation, I have delivered a seminar on Affinity Chromatography. Its Powerpoint presentation is not so good and I did not include much text in the ppt. Rather I have decided to include only the informative pictures and I explained the whole topic only with those pictures. (I got good grade for this!) So, here is this ppt. You can download it if you want! DOWNLOAD AFFINITY CHROMTOGRAPHY [PPT] For preparation of this topic I downloaded A Handbook of Affinity Chromatography. The principle and methods of this chromatography are well explained in this book. I am giving link of this book for you. Don't forget to download and read! DOWNLOAD HANDBOOK OF AFFINITY CHROMATOGRAPHY [PDF] Do you know the components of affinity m

UV-Visible spectroscopy: Basics

Ultraviolet Spectroscopy In this anaytical technique, ultraviolet radiations are used. Wavelength ranges of radiations: Visible light : 400 - 800 nm Near UV radiations : 200 - 400 nm Far/ Vacuum UV : below 200 nm Generally, we carry out UV analysis in near UV region of radiations. PRINCIPLE : Electronic transitions When a molecule absorbs UV radiations, the electronic excitation occur where electrons go from lower to higher energy state. Electronic excitation causes the electron to go from electron bonding orbital to antibonding orbital. After some time electron returns to its original state (stable). While returning to its stable form (into bonding orbital) it releases excess energy. That energy is measured by the detector to access the wavelength (λmax) /absorption pattern. TRANSITIONS: σ → σ* (126-135 nm) n → σ* (180-200 nm) π → π* n → π* ALLOWED TRANSITION: π → π* FORBIDDEN TRANSITIONS: n → π* ENERGY OF VARIOUS TRANSITIONS: σ