Background: Cinnarizine, an antihistaminic drug, is commonly formulated in combination with domperidone and with paracetamol for treatment and prevention of motion sickness and migraine.Objective: The aim of this work was to develop new, simple, precise and selective chromatographic methods (RP-HPLC and TLC-densitometric methods) for the determination of these drugs. These methods can be used as analytical tools in the routine examination in quality control laboratories.Methods: The first method was RP-HPLC method, the separation was carried out on an Inertsil® ODS- 3V C18 column (250 mm × 4.6 mm, 5 µm) using a mobile phase composed of methanol: acetonitrile (45: 55, v/v) at a flow rate of 1 ml/min. The detection was carried out at 220 nm. The second method was a TLC-densitometric method where the studied components were separated using a developing system composed of toluene: ethyl acetate: methanol: triethylamine (5: 4.3: 0.7: 0.5, v/v/v/v) on TLC silica gel 60 F254 plates, followed by densitometric scanning at 270 nm.Results: In RP-HPLC method, the peaks were sharp and well separated, the retention times were 5.25, 3.48 and 2.78 min, for cinnarizine, domperidone and paracetamol, respectively. Linearity was obtained over the concentration ranges 1-22, 0.75-16.5 and 25-550 µg/ml, for cinnarizine, domperidone and paracetamol, respectively. In TLC-densitometric method, good separation of spots and linear relationships were achieved over the concentration ranges of 0.2-2, 0.15-1.5 and 5-50 µg/spot, for cinnarizine, domperidone and paracetamol, respectively. Method validation was conducted according to ICH guidelines in terms of linearity, accuracy, selectivity, precision and robustness.Conclusion: The developed methods were applied for the determination of the cited drugs in tablets containing binary drug mixtures. The methods are simple and precise and can be used for routine analysis of the labelled drugs in combined dosage forms in quality control laboratories.

Objectives: The aim of this study was to compare in vitro dissolution of cefixime in a pharmacopeial-recommended medium and in simulated gastrointestinal fluids. Methods: Before dissolution testing, the drug content in the tested materials was determined by ultraviolet spectrophotometer. The dissolution media used in this study were recommended by the United States Pharmacopeia (USP) as well as four different media that mimic gastric and intestinal fluids in fed and fasted states. The tested materials included the pure drug and two 0.2-g capsule brands (original and test). Results: The pharmacopeial medium showed no difference in both extent and rate of the drug dissolution between the tested materials. In the contrary, the difference was significant when the simulated fluids were used. Moreover, it was found that the simulated intestinal fluid (SIF) of fed state showed 21–32% decrement in the drug dissolution compared to that of the corresponding fasted-state simulated fluid. Indeed, this finding agreed those of in vivo bioavailability studies published in literature. Conclusion: The SIF is much more valid as a medium for in vitro testing of cefixime capsule than the one recommended by the USP.

Background: Catha Edulis is a widespread plant in some countries such as Yemen. This plant is taken by most populations in Yemen and other countries and can affect the bioavailability of many drugs such as sildenafil. Objectives: The study aimed to knowledge and evaluation of the effect of the presence of khat in the GIT on the bioavailability and efficacy of sildenafil. Methods: The present study was carried out in ex-vivo by using everted gut sac method. In comparative studies for absorption of standard sildenafil alone and stand. sildenafil in presence of more than one type of khat (Ansi and Hamdani) and confirm this study by comparative study for sildenafil (Viagra) alone and in presence of the more effective type of khat (Ansi). Results: In the proposed studies, by using the calibration curve equation to calculate Conc. %, the means of the difference in Conc.% of the stand. sildenafil alone and stand. sildenafil in presence of khat Ansi and stand. sildenafil in presence of khat Hamdani were 14.14 ± 2.922 and 8.316 ± 0.868 respectively, and the mean difference in Conc.% of sildenafil (Viagra) alone and sildenafil (Viagra) in presence of khat ANSI was 19.986 ± 3.981. Conclusions: Based on the results obtained from the study, the sildenafil bioavailability was significantly reduced in the presence of khat. The rate of reduction was affected by the type of khat, as al-ANSI khat was more effective than al-Hamdani khat in the reduction of bioavailability of sildenafil.

Objectives: The objective of the present study was to check the potential presence of illicit drugs and to quantify the amount of nicotine in a buccal tobacco brand that had been observed to be increasingly used by Yemeni youths, since 2014, causing narcosis resembling states among them. Methods: Thin-layer chromatography (TLC) described by the United Nations Office on Drugs and Crime (UNODC) was used to screen illicit drugs in the tested brand. The illicit drugs investigated included opiates, heroin, amphetamines, and cocaine. The TLC results were confirmed as recommended by the UNODC using color chemical tests. Identification and quantification of nicotine in the brand was carried out using an appropriate high-performance liquid chromatography (HPLC) system. Results: No illicit drug was found in the tested tobacco brand. On the other hand, it was found that the amount of nicotine in just a single dose (sachet) of the buccal brand was 17.67±0.901 mg, which was 3.53-fold greater than usual buccal dose of nicotine (5 mg). Conclusion: With the exception of cannabis, opioids, and hallucinogens that were not investigated in this study due to technical obstacles, other major illicit narcotic drugs are not found in the brand. The brand contains high amount of nicotine/sachet. However, knowing that the user may use more than one sachet of the brands a day, there is a great potential of nicotine overdosing due to intake of the brand. This may cause a narcosis resembling state called “Nesbitt’s paradox,” characterized by reducing neuronal activity of the user.

Objective: The study aimed to assess the quality control of different brands of cefixime 400 mg capsule brands available in Yemeni drug market. Methods: The pharmacopeial specifications of five cefixime 400 mg capsule brands available in Yemeni drug market, including two domestic brands, were assessed in this study. Assessment included assay content, capsule weight variation and disintegration. In addition, drug dissolution and antimicrobial activity test were assessed. Results: Out of five brands, three brands of cefixime 400 mg capsules passed official specified assay tests according to United States Pharmacopeia (USP) specifications. The five brands showed a similar profile of weight variation and drug disintegration that were within the limits. However, the results of drug content for five brands showed in range 78.78-104.46 % in which three brands (B, D and E) in compliance to USP specifications (90-110%) and two brands (A and C) not compliance to USP specification. Also, the results of dissolution profile were in range 86.2-109.8% for four brands (A, B, D and E) that compliance to USP specifications, and 73.56% for brand C that was not compliance to USP specifications. Conclusion: Based on the results obtained in this study, the drug content for three brands (B, D, E) is within the pharmacopeial limit, but the drug content of (A, C) is out of the limit. while the capsule disintegration, weight variations, and antibacterial activity in all tested brands are within the pharmacopeial limit. The dissolution profile for four brands (A, B, D, E) is within the pharmacopeial limit, but the dissolution profile for (C) is less than the allowed limit.

Context: Catha edulis (khat) is a prevalent plant in Yemen and other African regions. In Yemen and other countries, most people chew this plant, which may change the pharmacokinetics of many drugs, such as anti-diabetics (glibenclamide and metformin). Aims: To evaluate the effect of C. edulis presence in the gastrointestinal tract (GIT) on the intestinal perfusion and bioavailability of metformin and glibenclamide and its effectiveness. Methods: The present study was conducted in situ using the closed-loop Doluisio’s method. Rat intestinal perfusion of a reference standard of each test drug alone was compared to the drug intestinal perfusion in the presence of C. edulis (three types of C. edulis agriculture in different regions of Yemen). The type of C. edulis that produced the most influence on the absorption of the drug reference was then re-investigated using the same in situ method against a pharmaceutical dosage form (tablets) of the drug. Results: The intestinal absorptions (perfusion) of reference standards of metformin and glibenclamide were decreased in the presence of C. edulis by 30.53-35.9% and 14.71-27.93%, respectively, while such decrease with pharmaceutical dosage form (tablets) of the two drugs was 24.24 and 19.77%, respectively. Conclusions: Based on the results reached from this study, the anti-diabetic bioavailability was significantly reduced in the presence of C. edulis, and this effect may affect the drug efficacy.