Cephalexin
M. Lindsay Grayson, Sara E. Cosgrove, Suzanne M. Crowe, M. Lindsay Grayson, William Hope, James S. McCarthy, John Mills, Johan W. Mouton, David L. Paterson in Kucers’ The Use of Antibiotics, 2017
Cephalexin (also spelled cefalexin) is a semisynthetic first-generation cephalosporin antibiotic intended for oral administration. Cephalexin was the first oral cephalosporin introduced for clinical use in 1969. It is 7-(D-alpha-amino-alpha-phenylacetamido)-3-methyl-3-cephem-4-carboxylic acid monohydrate. Cephalexin has the molecular formula CHNOS HO, and the molecular weight is 365.41; cephalexin’s chemical structure is illustrated in Figure 19.1. The nucleus of cephalexin is related to that of other cephalosporin antibiotics. Cephalexin has a D-phenylglycyl group as substituent at the 7-amino position and an unsubstituted methyl group at the 3-position. The compound is a zwitterion—that is, the molecule contains both a basic and an acidic group. The isoelectric point of cephalexin in water is 4.5–5. The crystalline form of cephalexin is a monohydrate. It is a white crystalline solid with a bitter taste. Solubility in water is low at room temperature; 1 or 2 mg/ml may be dissolved readily, but higher concentrations are obtained with increasing difficulty.
Infections
Anne Lee, Sally Inch, David Finnigan in Therapeutics in Pregnancy and Lactation, 2019
Asymptomatic bacteriuria is defined as urinary tract infection in the absence of any symptoms, with greater than 100 000 bacteria/mL in a midstream urine sample. It occurs in 5–10% of pregnancies, with similar prevalence in nonpregnant women. Escherichia coli is the most common pathogen; other organisms include Klebsiella species, Proteus species, enterococci, staphylococci and group B streptococcus. In non-pregnancy, asymptomatic bacteriuria is harmless and does not require treatment. In pregnancy, however, 20–30% of women will develop acute pyelonephritis unless treated. Asymptomatic bacteriuria is also associated with an increased risk of premature birth. Treatment of asymptomatic bacteriuria reduces the risk of acute pyelonephritis by 75% and possibly reduces the risk of premature birth by about 40%. It is uncertain how long a course of treatment should last. Single-dose therapy is not advised, but treatment for longer than three to seven days offers no additional advantage. Amoxycillin, nitrofurantoin and cefalexin are safe to use in pregnancy (Table 11.1). Amoxycillin is becoming less useful due to increasing rates of resistant E. coli. Nitrofurantoin is contraindicated in women suspected or known to have glucose-6-phosphate dehydrogenase (G6PD) deficiency, due to the risk of haemolysis. Trimethoprim has not been shown to harm the fetus if given during pregnancy. It is not recommended, however, especially in the first trimester, as it is a folate antagonist and theoretically teratogenic. Quinolones are not recommended because of adverse effects on developing cartilage in animal studies. Co-amoxiclav (a beta-lactam/beta-lactamase inhibitor combination) is probably safe, but experience is limited. Antenatal screening for asymptomatic bacteriuria is standard practice in the UK. Urine cultures every four to six weeks until delivery are advised following treatment of an episode of bacteriuria. More than three episodes of infection are an indication for prophylactic therapy with low-dose nitrofurantoin or cephalexin until delivery.
Information on level of drugs into breastmilk
Wendy Jones in Breastfeeding and Medication, 2018
Brand name: Keflex®, Ceporex®US brands: Biocef®, Cefanex®, Keflex®Australian brands: Cilex®, Ialex®, Ibilex®, Keflex®, Sporahexal®Cefalexin (cephalexin) is a first-generation cephalosporin antibacterial. Kafetzis et al. (1981) gave a single 1 g oral dose of cephalexin to six women in the immediate postpartum period. The maximum levels achieved in breastmilk were measured as 0.51 mg per litre. In Ito et al. ’s prospective study (1993) one of 11 women who took cephalexin reported diarrhoea in her infant which she attributed to exposure to the drug through breastmilk. Cephalexin is given directly to babies one month of age at a dose of 125 mg twice daily. Relative infant dose is quoted as 0.5% (Hale 2017 online access). The BNF states that it is present in breastmilk in low concentrations but that it is appropriate to use in breastfeeding mothers. ReferencesIto S, Blajchman A, Stephenson M, Prospective follow-up of adverse reactions in breastfed infants exposed to maternal medication, Am J Obstet Gynecol, 1993;168:1393–9. Kafetzis DA, Siafas CA, Georgakopoulos PA, Papadatos CJ, Passage of cephalosporins and amoxicillin into the breastmilk, Acta Paediatr Scand, 1981;70:285–8.
Cephalexin and Oxytetracycline Compared by Double-Blind Trial in the Treatment of Bronchitis in General Practice
Published in Current Medical Research and Opinion, 1974
Brenda M. Mullinger, R. D. Foord
Summary In a double-blind multi-centre trial conducted among general practices, cephalexin and oxytetracycline were compared for the treatment of bronchitis. The dosage, 250 mg. q.d.s.for 10 days, was the same for both drugs; if necessary the dose could be doubled on the third day. Two hundred and thirty-five patients were assessed clinically by their doctors at fixed intervals throughout the trial; all patients also recorded their own progress daily. A significantly higher number of patients were put onto double the dose of oxytetracycline at the third day, indicating a slower response to this drug compared with cephalexin. By the end of the trial the treatments were equally effective with a satisfactory response (recovery or marked improvement) for 93 % of acute bronchitics receiving cephalexin and 96 % receiving oxytetracycline. The corresponding figures for the chronic bronchitics were 92 % and 93 % respectively.
Design and evaluation of gastroretentive mucoadhesive cephalexin tablets
Published in Pharmaceutical Development and Technology, 2010
N.G. Sonani, S.P. Hiremath, F.S. Dasankoppa, V.G. Jamakandi, S.A. Sreenivas
The aim of this investigation was to develop gastroretentive mucoadhesive tablets of cephalexin, which will retain in the stomach for 10 h. Cephalexin, a first-generation cephalosporin, becomes ionized in intestinal pH because pKa is 4.5 and thus reducing its bioavailability. The various batches were prepared by wet granulation method using variety of mucoadhesive polymers such as hydroxyl propyl methyl cellulose K4M, hydroxyl propyl cellulose, chitosan, carbopol 934P and sodium carboxymethylcellulose and subjected to various evaluation parameters such as mucoadhesive strength, in vitro drug release profile, swelling characteristics and physical properties. It was evident from the study that the formulation containing HPMC K4M and carbopol 934P in combination exhibited maximum mucoadhesive strength of 144.42 gms, in vitro residence time was 8.73 h and in vitro drug release was found to be 75.03% in 10 h with non-Fickian diffusion mechanism. So, the optimized formulation F2 was further subjected to in vivo retention time in rabbit by X-ray technique, SEM and Accelerated stability studies. Regarding all the properties evaluated, the formulation containing HPMC K4M and carbopol 934P in combination was found to be the best to achieve the aim of this study.
Three-ways crossover bioequivalence study of cephalexin in healthy Malay volunteers
Published in Drug Development and Industrial Pharmacy, 2014
Kai Bin Liew, Kok Khiang Peh, Gabriel Onn Kit Loh, Yvonne Tze Fung Tan
Context: Although the general pharmacokinetics of cephalexin is quite established up-to-date, however, no population-based study on Cephalexin pharmacokinetics profile in Malay population has been reported yet in the literature. Objective: The objective of this study was to investigate the pharmacokinetics and to compare the bioavailability of three cephalexin products, Ospexin® versus MPI Cephalexin® tablet and MPI Cephalexin® capsule, in healthy Malay ethnic male volunteers in Malaysia. Material and method: A single dose, randomized, fasting, three-period, three-treatment, three-sequence crossover, open label bioequivalence study was conducted in 24 healthy Malay adult male volunteers, with 1 week washout period. The drug concentration in the sample was analyzed using high performance liquid chromatography. Result: The mean (SD) pharmacokinetic parameter results of Ospexin® were Cmax, 17.39 (4.15) μg/mL; AUC0–6, 28.90 (5.70) µg/mL * h; AUC0–∞, 30.07 (5.94) µg/mL * h; while, those of MPI Cephalexin® tablet were Cmax, 18.29 (3.01) μg/mL; AUC0–6, 30.02 (4.80) µg/mL * h; AUC00–∞, 31.33 (5.18) µg/mL * h and MPI Cephalexin® capsule were Cmax, 18.25 (3.92) μg/mL; AUC0–6, 30.04 (5.13) µg/mL * h; AUC0–∞, 31.22 (5.29) µg/mL * h. Conclusion: The 90% confidence intervals for the logarithmic transformed Cmax, AUC0–6 and AUC0–∞, of Ospexin® versus MPI Cephalexin® tablet and Ospexin® versus MPI Cephalexin® capsule were between 0.80 and 1.25. Both Cmax and AUC met the predetermined criteria for assuming bioequivalence. The pharmacokinetic profile of cephalexin in Malay population does not vary much from other world population.
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