Predictive Performance of Population Pharmacokinetic Models for Amikacin in Term Neonates.

BACKGROUND AND OBJECTIVE: Amikacin is preferred in treating Gram-negative infections in neonates and it has a narrow therapeutic window. The population pharmacokinetic modeling approach can aid in designing optimal dosage regimens for amikacin in neonates. In this study, we attempted to identify the suitable population pharmacokinetic model from the published reports for the study population from an Indian setting. METHODS: Published population pharmacokinetic studies for amikacin in neonates were identified. Data on structural models and typical pharmacokinetic parameters were extracted from the studies. For the clinical study, neonates who met the inclusion criteria were enrolled in the study from the NICU, Kasturba Medical College, Manipal, during Jan 2020 to March 2022. Drug concentrations were estimated, and demographic and clinical data were collected. Identified population pharmacokinetic models were used to predict the amikacin concentrations in neonates. Predicted concentrations were compared against the observed concentrations. Differences between predicted and observed concentrations were quantified using statistical measures. The population pharmacokinetic model, which was able to predict the data well, is considered a suitable model for the study population. Dosing regimens were suggested for neonates using the pharmacometric simulation approach generated by the selected model. RESULTS: A total of 43 plasma samples were collected from 31 neonates. Twelve population pharmacokinetic models were found for amikacin in neonates. The predictive performance of the 12 studies was performed using clinical data. A two-compartment model reported by Illamola et al. predicted the amikacin concentrations better than other models. Illamola et al. reported creatinine clearance and body weight as the significant covariates impacting the pharmacokinetic parameters of amikacin. This model was able to predict the clinical data with 29.97% and 0.686 of relative median absolute prediction error and relative root mean square error, respectively, which is the best among the published models. The Illamola et al. model was selected as the final model to perform pharmacometric simulations for the subjects with different combinations of creatinine clearance and body weight. Dosage regimens were designed to attain target therapeutic concentrations for the virtual subjects and a nomogram was developed. CONCLUSIONS: The population pharmacokinetic model reported by the Illamola et al. model was selected as the final model to explain the clinical data with the lowest relative median absolute prediction error and relative root mean square error when compared with other models. An amikacin nomogram was developed for the neonates whose creatinine clearance and body weight ranged between 10 and 90 mL/min and between 2 and 4 kg, respectively. A developed nomogram can assist clinicians to design an optimal dosage regimen of amikacin for term neonates.

In vitro antibacterial activity and in vivo pharmacokinetics of intravenously administered Amikacin-loaded Liposomes for the management of bacterial septicaemia.

Systemic delivery of amikacin is a widely adopted treatment modality for severe infections like sepsis. However, the current course of treatment requires repeated bolus doses of amikacin, prolonged hospitalization, and continuous therapeutic monitoring to manage the severe adverse effects. Amikacin has short half-life, which further challenges the delivery of sufficient systemic concentrations when administered by intravenous route. To solve this issue, novel delivery systems, amikacin liposomes (Ak-lip) were developed and evaluated for its antibacterial efficacy (agar plate diffusion and resazurin microtiter assay) and in vivo drug release in Sprague-Dawley rats. The Ak-lip were prepared by modified thin film hydration method and optimized based on particle size and Zeta potential. The zone of inhibition for Ak-lip and amikacin was found to be 22 mm and 26 mm against Staphylococcus aureus. The minimum inhibitory concentrations (MIC) of amikacin and Ak-lip against Staphylococcus aureus were found to be 3 µg/mL and 9 µg/mL, and for Pseudomonas aeruginosa were 0.6 µg/mL and 0.9 µg/mL respectively. The in vivo pharmacokinetic parameters were determined using Gastroplus™. A significant difference in the pharmacokinetic parameters (AUC, Cmax) was observed between amikacin and Ak-lip. The developed formulation showed good colloidal stability and sustained release profile up to 72 h which can reduce dosing frequency, minimize hospitalization and improve bactericidal activity at lower concentrations paving the path for improved therapeutic interventions in the treatment of sepsis.

Validation of an HPLC method for estimation of cefotaxime from dried blood spot: alternative to plasma-based PK evaluation in neonates.

Aim: Pharmacokinetic evaluation of cefotaxime in neonates is currently a challenge due to the large volume requirement of blood for its analysis by existing methods. A dried blood spot (DBS) based method is the best alternative. Materials & methods: We validated an HPLC method for estimation of cefotaxime from DBS and plasma. Extraction employed a simple procedure using acetonitrile and buffer. Selective separation of cefotaxime was achieved on a C8 column using gradient programming. Results & conclusion: The linearity of the method ranged from 2 to 200 µg/ml with acceptable precision and accuracy for both plasma and DBS. Hematocrit was not affecting the assay accuracy. A strong correlation and interchangeability observed with the plasma method proves its clinical validity for application to PK evaluations.

Lay abstract Cefotaxime is a widely used antibiotic in the neonatal population for treating bacterial infections. At the same time, determining the dosage for this antibiotic in the vulnerable population is always a challenge for the treating doctor. In the case of neonates, organs are not fully developed and their response to drugs will be different from that of adults. In the current clinical practice, dosage for neonates is deduced from pediatric dose without addressing this difference in the response. The major challenge in addressing this issue is the collection of blood by venipuncture from neonates for drug analysis. In this report, a microsampling technique called dried blood spot is used for sampling and bioanalysis of cefotaxime. The method is validated for estimation of cefotaxime from the neonatal blood.

Design and Synthesis of Novel Anti-inflammatory/Anti-ulcer Hybrid Molecules with Antioxidant Activity.

BACKGROUND: NSAIDs are the most widely prescribed medications worldwide for their anti-inflammatory, antipyretic, and analgesic effects. However, their chronic use can lead to several adverse drug events including GI toxicity. The selective COX-2 inhibitors developed as gastrosparing NSAIDs also suffer from serious adverse effects which limit their efficacy. OBJECTIVE: Local generation of reactive oxygen species is implicated in NSAID-mediated gastric ulceration and their combination with H2 antagonists like famotidine reduces the risk of ulcers. The objective of this work was to design and synthesize novel methanesulphonamido isoxazole derivatives by hybridizing the structural features of NSAIDs with those of antiulcer drugs (ranitidine, famotidine, etc.) to utilize a dual combination of anti-inflammatory activity and reducing (antioxidant) potential. METHODS: The designing process utilized three dimensional similarity studies and utilized an isoxazole core having a potential for anti-inflammatory as well as radical scavenging antioxidant activity. The compounds were assayed for their anti-inflammatory activity in established in vivo models. The in vitro antioxidant activity was assessed in potassium ferricyanide reducing power (PFRAP) assay employing ascorbic acid as the standard drug. RESULTS: Compounds 5, 6, 9 and 10 showed antiinflammatory activity comparable to the standard drugs and were also found to be non-ulcerogenic at the test doses. Compounds 6-10 exhibited good antioxidant effect in the concentration range of 1.0- 50.0 µmol/ml. The test compounds were also found to comply with the Lipinski rule suggesting good oral absorption. CONCLUSION: A new series of isoxazole based compounds is being reported with good antiinflammatory activity coupled with antioxidant potential as gastro-sparing anti-inflammatory agents.

Synthesis of methanesulphonamido-benzimidazole derivatives as gastro-sparing antiinflammatory agents with antioxidant effect.

A series of 5-methanesulphonamido benzimidazole derivatives were designed by combining the structural features of clinically useful anti-inflammatory drugs (nimesulide and rofecoxib) and antiulcer drugs (lansoprazole, omeprazole, etc.) based on physicochemical and 3D similarity studies. The compounds were evaluated for their anti-inflammatory activity in carrageenan induced rat paw edema model taking rofecoxib and indomethacin as standard drugs. In vitro antioxidant activity of the compounds was assessed by potassium ferricyanide reducing power (PFRAP) assay. The compounds 9, 10 and 11 showed anti-inflammatory activity comparable to the standard group and were also non-ulcerogenic at the test doses. Compounds 6-11 exhibited good antioxidant effect in the concentration range (1.0-50.0µmol/ml. Preliminary theoretical ADME profiling of the compounds based on computation of selected physicochemical properties showed an excellent compliance with Lipinski's rule.