Muhammad Ali Sheraz

Baqai Medical University · Baqai Institute of Pharmaceutical Sciences

Background L–Ascorbic acid (AA) is a highly unstable compound, thus, limiting its use in pharmaceutical and cosmetic products, particularly at higher concentrations. Objective This study aimed to stabilize the highly sensitive molecule (AA) by encapsulating it in β-cyclodextrin nanosponges (β-CD NS) that can be used further in preparing cosmeceuti...

Tolfenamic acid (TA) is commonly used in humans and animals because of its anti‐inflammatory, antipyretic, and analgesic effects. So far, no study has been carried out to develop a validated spectrofluorimetric method for determination of TA. Therefore, the present study aimed to develop and validate a simple, accurate, rapid, economical, and preci...

This investigation involves a study of the photochemical interaction of riboflavin (RF) and bovine serum albumin (BSA) in aqueous solution and the evaluation of this effect on the photostabilization of RF. RF solution (5 × 10–5 M) were irradiated with visible light in the presence of BSA (4.0–6.0 × 10–5 M) at pH 7.4 (0.005 M, phosphate buffer salin...

This is the first study on the photolysis of carboxymethylflavin (CMF), an intermediate in the photolysis of riboflavin (RF). CMF is photodegraded by removal of side-chain to lumichrome (LC) in acid solution and to LC and lumiflavin (LF) in alkaline solution. It also undergoes alkaline hydrolysis to 1,2-dihydro-1-methyl-2-keto-3-quinoxaline carboxy...

A stability‐indicating spectrofluorimetric method has been developed for the simultaneous assay of riboflavin (RF) and photoproducts, formylmethylflavin (FMF), lumichrome (LC) and lumiflavin (LF) in aqueous solution. The method is based on the extraction of LC formed in acid solution and LC and LF formed in alkaline solution with chloroform at pH 2...

A stability-indicating photochemical method has been developed for the assay of thiamine (TH) salts in aqueous solution and in fresh and aged vitamin preparations. It is based on the photooxidation of TH by UV irradiation to form thiochrome (TC) in alkaline solution. The TC : TH ratio under controlled conditions of light intensity, temperature, pH,...

Tolfenamic acid (TA) is a nonsteroidal antiinflammatory drug and belongs to the group of fenamates. It is used as a potent pain reliever in the treatment of acute migraine attacks, and disorders like dysmenorrhea, rheumatoid, and osteoarthritis. TA has shown excellent in vitro antibacterial activity against certain ATCC strains of bacteria when com...

Abstract: Background: Amikacin sulfate (AMK) belongs to the class of aminoglycoside antibiotics. It is effective against the infections caused by Gram-negative and positive bacteria. AMK lacks a chromophore group in its structure and, therefore, it does not absorb light in the 200-800 nm region which makes it a difficult molecule to analyze by UV d...

Background: Carvedilol (CD) is a β-blocker drug that is used in the treatment of hypertension, coronary diseases, etc. The official methods for the assay of CD in British Pharmacopoeia (BP) and United States Pharmacopeia (USP) include potentiometric titration and HPLC analysis, respectively. There are two different methods reported in the USP; one...

Pharmaceutical preparations may contain a single ingredient or multi-ingredients as well as excipients. In multicomponent systems, specific analytical methods are required to determine the concentrations of individual components in the presence of interfering substances. Ultraviolet and visible spectrometric methods have widely been developed for t...

Introduction Sulfacetamide sodium is a widely used sulfonamide for ophthalmic infections. Objective A number of analytical methods have been reported for the analysis of sulfacetamide but they lack the ability to determine both the active drug and its major degradation product, sulfanilamide, simultaneously in a sample. Materials and Methods In t...

PREFACE This monograph has been prepared to meet the requirements of M. Phil./Ph. D. courses in drug stability and related fields taught in the Faculties of Pharmaceutical Sciences in Pakistan. It covers a wide range of topics related to drug stability with chapters on general introduction and those concerning chemical kinetics, chemical stability...

Fluoroquinolone antibiotics are extensively used for the treatment of various infectious diseases. These compounds possess a quinolone nucleus, a fluoro group, a keto group, a carboxylic acid side chain and other moieties. These structural features and the ionization behavior of these compounds impart such physical properties that could be utilized...

The importance of novel drug delivery systems (NDDS) is increasing enormously because of the several advantages over conventional drug delivery systems. In the past few decades, the formulation of sponges is considered as one of the most emerging fields in the NDDS. Nanosponges (NS) entrap the drug in porous polymeric spheres ranging from 100 nm to...

Amlodipine (AD) is a calcium channel blocker that is mainly used in the treatment of hypertension and angina. However, latest findings have revealed that its efficacy is not only limited to the treatment of cardiovascular diseases as it has shown to possess antioxidant activity and plays an important role in apoptosis. Therefore, it is also employe...

Photostability studies of drugs and drug products are an integral part of the product development process in the pharmaceutical industry. These studies are carried out to ensure quality, efficacy, and safety of the formulated products during manufacture, storage, and use. This review deals with the concept of photostability and related aspects and...

A study of the effect of ionic strength on the photodegradation reactions (photoreduction and photoaddition) of riboflavin (RF) in phosphate buffer (pH 7.0) has been carried out using a specific multicomponent spectrometric method. It has been found that the rates of photodegradation reactions of RF are dependent upon the ionic strength of the solu...

A study of the formulation of liposomal preparations of riboflavin (RF) with compositional variations in the content of phosphatidylcholine (PC) and their entrapment efficiency (26-42%) have been conducted. Light transmission characteristics of the liposomal preparations have been determined to evaluate their effect on the amount of light passing t...

Ascorbic acid (vitamin C) is extensively used in a variety of formulations including creams. It is an ingredient of anti-aging cosmetic products alone or along with alpha-tocopherol (vitamin E). In solutions and creams, ascorbic acid is susceptible to air and light and undergoes oxidative degradation to dehydroascorbic acid and further to inactive...

The kinetics of photolysis of riboflavin (RF) in water (pH 7.0) and in organic solvents (acetonitrile, methanol, ethanol, 1-propanol, 1-butanol, ethyl acetate) has been studied using a multicomponent spectrometric method for the assay of RF and its major photoproducts, formylmethylflavin and lumichrome. The apparent first-order rate constants (k ob...

A stability-indicating photochemical method for the assay of riboflavin (RF) in photodegraded samples and aged vitamin preparations has been developed. It is based on photochemical conversion of RF to lumichrome (LC) in alkaline solution under controlled conditions of light intensity, temperature, pH, time of exposure, and distance. Under these con...

In the present work the effect of boric acid (BA) on the stabilization of ascorbic acid (AH2) in cream formulations has been studied. The oil-in-water creams of AH2 (pH 6.0) were prepared and exposed to ultraviolet radiation and also kept in dark at 25 ± 1 °C. The apparent first-order rate constants for the degradation of AH2 (0.42-1.20 × 10–3 min–...

The present study has been carried out to validate a UV spectrometric method for the assay of tolfenamic acid (TA) in organic solvents. TA is insoluble in water; therefore, a total of thirteen commonly used organic solvents have been selected in which the drug is soluble. Fresh stock solutions of TA in each solvent in a concentration of 1 × 10 −4...

The kinetics of photodegradation of moxifloxacin (MF) in aqueous solution (pH 2.0–12.0), and organic solvents has been studied. MF photodegradation is a specific acid-base catalyzed reaction and follows first-order kinetics. The apparent first-order rate constants (k obs) for the photodegradation of MF range from 0.69 × 10−4 (pH 7.5) to 19.50 × 10−...

Riboflavin (RF), also known as vitamin B2, belongs to the class of water-soluble vitamins and is widely present in a variety of food products. It is sensitive to light and high temperature, and therefore, needs a consideration of these factors for its stability in food products and pharmaceutical preparations. A number of other factors have also be...

Objective The present investigation is based on the formulation of different water-in-oil (w/o) creams of ascorbic acid (AA) as a potential topical or cosmetic preparation for anti-aging purpose. The effect of different excipients, medium pH and viscosity on the chemical as well as physical stability of AA during storage has been evaluated.Methods...

Objectives The present study was carried out to create composites and fibers using polyurethane (PU) with hydroxyapatite (HA) that could be used for dental applications. Methods Composites with varying HA concentration were prepared by solution casting technique. Similarly, PU–HA fibers with varying PU hard and soft segments and fixed HA concentra...

The degradation kinetics of 5 × 10−5 M cyanocobalamin (B12) and hydroxocobalamin (B12b) in the presence of ascorbic acid (AH2) was studied in the pH range of 1.0–8.0. B12 is degraded to B12b which undergoes oxidation to corrin ring cleavage products. B12b alone is directly oxidized to the ring cleavage products. B12 and B12b in degraded solutions w...

Riboflavin (RF) is a light sensitive compound and is known to form a number of photoproducts. These photoproducts possess the same nucleus and may interfere in the analysis of RF by UV and visible spectrometry. Therefore, it is necessary to apply the methods of multicomponent spectrometric analysis to quantify the vitamin and its photoproducts accu...

tA study of the photodegradation of 5 × 10−5M riboflavin (RF) in 0.2–1.0 M phosphate buffer in the pres-ence and absence of 2.50 × 10−4M caffeine at pH 6.0–8.0 has been carried out. RF in phosphate buffer isphotodegraded simultaneously by normal photolysis (photoreduction) and photoaddition reactions giv-ing rise to lumichrome (LC) and cyclodehydro...

Abstract Tolfenamic acid (TA) has been transformed from crystalline to amorphous state through freeze-drying by using varying ratios of polyacrylic acid (PA) at various pH values. The characterization of the films has been carried out using X-ray diffraction, differential scanning calorimetry, Fourier transform infrared (FTIR) spectrometry and scan...

An emulsion is a dispersed system consisting of at least two immiscible liquids, one of which is an internal or dispersed phase (dispersed as globules) within the external or continuous phase (other liquid phase), generally stabilized by an emulsifying agent. Emulsions have been widely used in many areas including petroleum, agriculture, food, phar...

Efficacy of photoinitiators such as riboflavin (RF), camphorquinone (CQ), and safranin T (ST) and triethanolamine as a coinitiator has been compared in carrying out the polymerization of 2-hydroxyethyl methacrylate (HEMA) in aqueous and organic solvents. HEMA solutions were polymerized in the presence of RF, CQ, and ST using a low intensity visible...

In the spectrophotometric assay of multicomponent systems involved in drug degradation studies, some minor or unknown degradation products may be present. These products may interfere in the assay and thus invalidate the results due to their absorption in the range of analytical wavelengths. This interference may be eliminated by the application of...

The quantitative analysis of Tolfenamic Acid (TA) both as a pure compound and in tablet dosage form has been carried out using FT-IR and UV spectroscopy. In the FT-IR method, a number of characteristic absorption peaks were examined that could be used for analytical purpose. The analysis was carried out by preparing calibration curves of peak heigh...

The kinetics of photodegradation of levofloxacin in solution on UV irradiation in the pH range 2.0-12.0 has been studied using a HPLC method. Levofloxacin undergoes first-order kinetics in the initial stages of the reaction and the apparent first-order rate constants are of the order of 0.167 to 1.807×10-3 min-1. The rate-pH profile is represented...

Solid-state properties of tolfenamic acid (TA) and its complexes with chitosan (CT) have been studied. Effect of medium pH, molecular weight of polymer and its different concentrations on these TA-CT complexes were studied in detail. Low and medium molecular weight CT have been used in different ratios at pH ranging from 4 to 6 and freeze-drying te...

The kinetics of the photolysis of formylmethylflavin, a major intermediate product in the aerobic and anaerobic photolysis of riboflavin, was studied in the pH range 2.0-11.0. Formylmethylflavin and its photoproducts, lumichrome and lumiflavin, were determined in degraded solutions using a specific multicomponent spectrophotometric method. The phot...

The effects of solvent [acetonitrile, methanol, and acetonitrile/water mixture (20:80, v/v)], buffer concentration (phosphate buffer, pH 7.5), ionic strength and commonly employed adjuvants on the photodegradation of betamethasone-17 valerate in cream and gel formulations have been studied on exposure to UV light (300-400 nm). A validated high-perf...

The present study deals with the preparation of polyurethane (PU) films impregnated with a nonsteroidal anti-inflammatory drug, tolfenamic acid (TA). Solvent evaporation technique has been employed for the preparation of TA-PU films in two different ratios of 1 : 2 and 1 : 5 in Tetrahydrofuran (THF) or THF-ethanol mixtures. The prepared films were...

The efficacy of various dosage forms (e.g. tablet, etc.) rely profoundly on the dissolution rate before their absorption and becoming available to the target site. Therefore, much importance is given to dissolution testing in pharmaceutical industry. A number of factors have been identified that can influence or alter the dissolution of a particula...

The glass ionomer cements (GICs) are widely used in dentistry as restorative materials. These are formed by the reaction of fluoro-alumino-silicate glass with an acidic polyelectrolyte such as poly (acrylic acid). The setting mechanisms in GICs are based on polyacid neutralization and free radical polymerization reactions. The free radical polymeri...

The polymerization of 1-3 M 2-hydroxyethyl methacrylate (HEMA) initiated by riboflavin/triethanolamine system has been studied in the pH range 6.0-9.0. An approximate measure of the kinetics of the reaction during the initial stages (~5% HEMA conversion) has been made to avoid the effect of any variations in the volume of the medium. The concentrat...

The present study deals with the preparation of polyurethane (PU) films impregnated with a nonsteroidal anti-inflammatory drug, tolfenamic acid (TA). Solvent evaporation technique has been employed for the preparation of TA-PU films in two different ratios of 1 : 2 and 1 : 5 in Tetrahydrofuran (THF) or THF-ethanol mixtures. The prepared films were...

The present work is based on a study of the effect of some vitamins such as riboflavin (RF), nicotinamide (NA) and alpha-tocopherol (TP) on the photodegradation of ascorbic acid (vitamin C) (AH₂) in oil-in-water cream formulations using a UV irradiation source. A UV spectrophotometric and the official iodimetric methods have been used for the assay...

This study involves the evaluation of the effect of certain stabilizers, that is, citric acid (CT), tartaric acid (TA) and boric acid (BA) on the degradation of ascorbic acid (AH(2) ) in oil-in-water cream formulations exposed to the UV light and stored in the dark. The apparent first-order rate constants (0.34-0.95 × 10(-3) min(-1) in light, 0.38-...

The kinetics of photolysis of ascorbic acid in cream formulations on UV irradiation has been studied using a specific spectrophotometric method with a reproducibility of ±5%. The apparent first-order rate constants (k obs) for the photolysis of ascorbic acid in creams have been determined. The photoproducts formed in the cream formulations include...

Ascorbic acid (vitamin C) and its derivatives are known to perform various important physiological and metabolic functions in humans. In addition to dietary supplements, a number of topical formulations containing ascorbic acid and derivatives are now available that induce collagen synthesis, strengthening of skin tissues, reduction in pigmentation...

In the present investigation the photolysis of riboflavin (RF) in the presence of citrate species at pH 4.0–7.0 has been studied. A specific multicomponent spectrophotometric method has been used to assay RF in the presence of photoproducts during the reactions. The overall first-order rate constants (kobs) for the photolysis of RF range from 0.42...

Boric acid and sodium borate are pharmaceutical necessities and are used as antiinfective agents and as a buffer in pharmaceutical formulations. Boric acid is used as an antimicrobial agent for the treatment of Candida, Aspergillus and Trichomonas infections. It is employed in the treatment of psoriasis, acute eczema, dermatophytoses, prostrate can...

The glass ionomer cements (GICs) are widely used in dentistry as restorative materials. These are formed by the reaction of fluoro-alumino-silicate glass with an acidic polyelectrolyte such as poly (acrylic acid). The setting mechanisms in GICs are based on polyacid neutralization and free radical polymerization reactions. The free radical polymeri...

Borates are among the most widely used compounds in chemical and related fields. They have extensive applications in consumer products including pharmaceuticals, cosmetics, insecticides, preservatives, detergents, bleaching agents and enamels. This new book provides a thorough background of the chemical, pharmaceutical and pharmacological aspects o...

The labels naphthalene-2,3-dicarboxaldehyde (NDA), 1-phenylnaphthalene-2,3-dialdehyde (ΦNDA), and anthracene-2,3-dialdehyde (ADA) have been used as fluorigenic reagents. They formed fluorescent derivatives with proteins. The derivatives formed are in fact isoindoles. The fluorescence decay of the labels-antibody was found to extend over a period of...

The present investigation is based on a study of the effect of buffer and non-buffer divalent anions (phosphate, sulphate, tartrate, succinate, malonate) on the kinetics, product distribution and photodegradation pathways of riboflavin (RF) at pH 6.0-8.0. RF solutions (5x10(-5)M) were photodegraded in the presence of divalent anions (0.2-1.0M) usin...

Boric acid and inorganic borates are important chemical compounds which are toxic in nature and show symptoms of poisoning on oral ingestion of as little as 5 g or on topical application to damaged skin. Boric acid induces reproductive and developmental toxicity in mice, rats and rabbits. It has been shown to produce cytotoxic, embryotoxic, genotox...

Parkinson's disease (PD) is one of the most common neurodegenerative disorders featuring the cardinal symptoms of resting tremors, postural instability, rigidity, bradykinesia and akinesia treated with a range of medicinal agents. The traditional drug therapy usually involves levodopa, the most potent drug for controlling PD symptoms, along with ca...

The effect of caffeine complexation with riboflavin on the kinetics of riboflavin photolysis in the pH range 2.0-10.5 has been studied. The photolysis of riboflavin solutions (5x10(-5) M) was carried out in the presence of caffeine (0.5-2.5x10(-4) M) using a visible radiation source. A specific multicomponent spectrophotometric method was used for...

Full thesis available at: http://eprints.hec.gov.pk/5442/

The photolysis of riboflavin (RF) in the presence of borate buffer (0.1-0.5M) at pH 8.0-10.5 has been studied using a specific multicomponent spectrophotometric method for the determination of RF and photoproducts, formylmethylflavin (FMF), lumichrome (LC) and lumiflavin (LF). The overall first-order rate constants for the photolysis of RF (1.55-4....