INTRODUCTION:

The Cephalosporins are a class of β-lactam antibiotics originally derived from the fungus Acremonium, which was previously known as "Cephalosporium". Together with cephamycins, they constitute a subgroup of β-lactam antibiotics called cephems. The nucleus consists of a beta-lactam ring fused to a dihydrothiazine ring (7-aminocephalosporanic acid). By addition of different side chains at position 7 of beta-lactam ring and at position 3 of dihydrothiazine ring, a large number of semi synthetic compounds have been produced. Cephalosporin’s have been conventionally divided into 4 generations¹.

Figure 1: General structure of Cephalosporins

Ceftazidime is a semi synthetic, broad-spectrum, beta-lactam antibiotic useful for the treatment of a number of bacterial infections. Ceftazidime is a third-generation cephalosporin antibiotic bearing pyridinium-1-ylmethyl and {[(2Z)-2-(2-amino-1,3-thiazol-4-yl)-2-{[(2-carboxypropan-2-yl)oxy]imino}acetamido groups at positions 3 and 7, respectively, of the cephem skeleton. The criteria for qualification as a third-generation agent generally accepted, are: (1) high stability to/ Mactamases, particularly those produced by Gram-negative bacteria, (2) high potency against all, or at least most of, the Enterobacteriaceae, and (3) moderate-to-good activity against Pseudomonas aeruginosa.^3-5

Figure 2: Structure of Ceftazidime

Specifically it is used for joint infections, meningitis, pneumonia, sepsis, urinary tract infections, malignant otitis externa, Pseudomonas aeruginosa infection, and vibrio infection. It is given by injection into a vein or muscle.

Septic arthritis, also known as infectious arthritis, is the invasion of a joint by an infectious agent resulting in joint inflammation. Symptoms typically include redness, heat and pain in a single joint associated with a decreased ability to move the joint. Other symptoms may include fever, weakness and headache. Occasionally, more than one joint may be involved. Causes include bacteria, viruses, fungi and parasites.

Meningitis is an acute inflammation of the protective membranes covering the brain and spinal cord, known collectively as the meninges. The most common symptoms are fever, headache, and neck stiffness. The inflammation may be caused by infection with viruses, bacteria, or other microorganisms, and less commonly by certain drugs.

Pneumonia is an inflammatory condition of the lung affecting primarily the small air sacs known as alveoli. Typically symptoms include some combination of productive or dry cough, chest pain, fever, and trouble breathing. Pneumonia is usually caused by infection with viruses or bacteria and less commonly by other microorganisms, certain medications and conditions such as autoimmune diseases.

Sepsis is a life-threatening condition that arises when the body's response to infection causes injury to its own tissues and organs. Common signs and symptoms include fever, increased heart rate, increased breathing rate, and confusion.

A urinary tract infection (UTI) is an infection that affects part of the urinary tract. Symptoms from a lower urinary tract infection include pain with urination, frequent urination, and feeling the need to urinate despite having an empty bladder. Symptoms of a kidney infection include fever and flank pain usually in addition to the symptoms of a lower UTI.

Otitis externa, also called swimmer's ear, is inflammation of the ear canal. It often presents with ear pain, swelling of the ear canal, and occasionally decreased hearing. Typically there is pain with movement of the outer ear.^6-9

Mechanism of Action of Ceftazidime:

1. All cephalosporin’s interfere with the synthesis of bacterial cell wall. The bacteria synthesize UDP-N-acetylmuramic acid pentapeptide called ‘Park nucleotide’ and UDP-N-acetyl glucosamine.

2. The peptidoglycan residues are linked together forming long strands and UDP is split off.

3. The final step is cleavage of the terminal D-alanine of the peptide chains by transpeptidases, the energy so released is utilized for establishment of cross linkages between peptide chains of the neigh boring strands. This cross linking provides stability and rigidity to the cell wall.

4. These antibiotics inhibit the transpeptidases so that cross linking does not take place. These enzymes and related proteins constitute the penicillin binding proteins (PBPs) and PBPs obtained from different species differ in their affinity towards different beta-lactam antibiotics.

5. When susceptible bacteria divide in the presence of a beta-lactam antibiotic, cell wall deficient forms swell and burst causing bacterial lysis.

6. Under certain conditions and in case of certain organisms, bizarre shaped or filamentous forms, which are incapable of of multiplying, result.

7. Grown in hyperosmotic medium, globular giant forms or protoplasts are produced. Lytic effects of these antibiotics may also be due to depression of some bacterial autolysins which normally function during cell division.

8. These antibiotics are more lethal during the phase of rapid cell wall synthesis.

9. The peptidoglycan cell wall is unique to bacteria. No such substance is synthesized particularly, D-alanine is not utilized by higher animals. Therefore, cephalosporin’s are non-toxic to man.⁹

Figure 3: Diagrammatic representation of bacterial cell wall synthesis and its inhibition by cephalosporins

Figure 4: MOA of Ceftazidime

Analytical Method:

Ceftazidime quantification in powder for injection by the infrared spectroscopic method demonstrated good linearity, precision and accuracy at concentrations ranging from 0.5 to 7.0 mg. The present investigation showed that infrared analysis could be also employed for quantitative determination of ceftazidime in pharmaceutical preparations, with possible application for quantification of other drugs. Therefore, it was an acceptable alternative method for the routine quality control of ceftazidime in raw material and pharmaceuticals. The proposed method used simple reagents, with minimum sample preparation procedures, encouraging its application in routine analysis.

Figure 5: Infrared spectrum for ceftazidime reference substance

Figure 6: Calibration curve for ceftazidime by infrared spectroscopic proposed method

Ceftazidime/Avibactam:

Ceftazidime-avibactam is a combination of a third-generation cephalosporin and a synthetic, non-β-lactam, β-lactamase inhibitor (BLI) approved by the United States Food and Drug Administration (FDA) in early 2015 and received marketing authorization by the European Medicines Agency (EMA) in April 2016. The addition of avibactam to ceftazidime expands its spectrum of activity to include Ambler class A, C, and some class D, β-lactamases in Enterobacteriaceae resistant to carbapenems and ceftazidime alone. Under the United States Generating Antibiotic Incentives Now (GAIN) Act, ceftazidime-avibactam was granted approval for treatment of complicated urinary tract infections (cUTIs) and complicated intra-abdominal infections (cIAIs) based on data from phase I and II clinical trials. Use should be reserved for patients with limited to no options for the treatment of multidrug-resistant Gram-negatives. It is on the World Health Organization's List of Essential Medicines, the safest and most effective medicines needed in a health system. It is given by injection into a vein.

Avibactam: it is chemically known as [(2S,5R)-2-carbamoyl-7-oxo-1,6-diazabicyclo[3.2.1]octan-6-yl] sulfate. Its molecular weight is 287.23. The empirical formula is C₇H₁₀N₃O₆S. Avibactam is a novel non-β-lactam β-lactamase inhibitor which protects ceftazidime from hydrolysis by a wide range of serine β-lactamases. Importantly, the range of inhibition of AVI includes class A ESBLs and carbapenemases (e.g. KPCs), class C β-lactamases and some class D oxacillinases and carbapenemases.

Figure 7: Chemical structure of Avibactam

Antimicrobial Activity Assessment:

The newly synthesized derivatives were tested for their antimicrobial activity by disc-diffusion method against the following microorganisms:

a) Gram-negative: Escherichia coli and Pseudomonas aeruginosa

b) Gram-positive: Streptococcus spp and Staphylococcus aureus.

Type of media used: (Nutrient Medium), which contain 1g/L distilled water, peptone (5gm) and meat extract (3gm), and the pH was adjusted to 7.0. Each of the synthesized compounds (30g) was dissolved in dimethylsulphoxide to prepare the test solutions. Ceftazidime (30g) was used as the standard antibacterial drug. Dimethylsulphoxide: water mixture (1:30) was used as the solvent.

RESULTS AND DISCUSSION:

The antimicrobial screening revealed that the newly synthesized compounds (2 and 4) showed reasonable antibacterial activities against G (+) Strep. Spp. in comparison with ceftazidime, which has no activity against this type of microorganism. Compound 2 showed good activity against all 4 strains of bacteria used, as compared with ceftazidime. Compound 4 showed good and reasonable activities against E. coli and P. aeruginosa comparable with ceftazidime. While, it showed good activity against Strep. Spp. and moderate activity against Staph. aureus. Compound 1 showed moderate activity against Strep. Spp. and staph Spp. and good activity against E. coli and P. aeruginosa. Compound 3 showed good and reasonable activity against E. coli and P. aeruginosa and moderately active towards staph. Spp. However, compound 3 showed no activity against Strep. Spp. Compound 5 showed good activity against E. coli and moderate activity against P. aeruginosa. Generally, all the Schiff bases of ceftazidime (compounds 1, 2 and 4) showed good and reasonable antimicrobial activity against the tested microorganisms especially G(+) bacteria.

This increase in activity may be due to the incorporation of extra imine groups. The slight reduction in antibacterial activities of some of these derivatives (compounds 3 and 5) as compared with ceftazidime is observed, but these may still have potential to be used as therapeutic agents. Compounds 3 and 5 that are devoid of the extra imine groups and contain two primary amine groups have moderate to slight activities as compared to ceftazidime. Compounds 2 and 4 showed broader antibacterial spectrum against both G(+) and G(-) bacteria. The Schiff bases of lysine (2, 6-bis (benzylideneamino)) hexanoic acid (compound 2a) exhibit slight activities towards E. coli and strep. Spp, as compared with lysine which has no antibacterial activity. However, compound 2a showed no antimicrobial activities against S. aureus or P. aeruginosa.

REFERENCES:

1. Fu, K. P. and Neu, H. C. Antibacterial activity of ceftizoxime, a beta-lactamase-stable cephalosporin. Antimicrobial Agents and Chemotherapy. 1980; (17): 583-90.

2. Hoover, J. R. E. and Dunn, G. L. The beta-lactam antibiotics. In Burger's Medicinal Chemistry, 1979; 4: 83-172.

3. Morita, K et al. An approach to broad spectrum cephalosporin’s, Philosophical Transactions of the Royal Society of London, 1980 (81-90).

4. Nakano, H. Structure-activity relationships related to ceftizoxime. Medicinal Research Reviews, 1981; 1: 27-57.

5. O'Callaghan et al. Cefuroxime, a new cephalosporin antibiotic: activity in vitro. Antimicrobial Agents and Chemotherapy, 1980 (511)

6. Pandeya S.N, Textbook of Medicinal Chemistry, S.G. Publications, Varanasi, 2003; 2: 802.

7. Phillips, I., et al. Ceftazidime: in-vitro antibacterial activity and susceptibility to /Mactamases compared with that of cefotaxime, moxalactam and other beta-lactam antibiotics. Journal of Antimicrobial Chemotherapy, 2001; (2): 23-31.

8. Tribuddharat C, et al. Burkholderiapseudo mallei class a beta-lactamase mutation that confer selective resistance against ceftazidime or clavulanic acid inhibition. Antimicrobial Agents Chemotherapy 2003; 47: 82-87.

9. Tripathi K.D, Essentials of Medical Pharmacology, Jaypee Brothers Medical Publishers, Delhi, 2019; 8^th ed: pp. 775, 766-767.

Received on 28.03.2020 Modified on 08.07.2020

Research J. Pharm. and Tech. 2021; 14(8):4517-4520.

DOI: 10.52711/0974-360X.2021.00786