Gabriel Kigen
Associate Professor of Pharmacology & Therapeutics
Department of Pharmacology & Toxicology, Moi University School of Medicine
Eldoret, Kenya
Recent Publications
Nguata M, Orwa J, Kigen G, Kamaru E, Emonyi W, Kariuki S, Newton C, Ongeri L, Mwende R, Gichuru S, Atwoli L. Association between psychosis and substance use in Kenya. Findings from the NeuroGAP-Psychosis study. Frontiers in PsychiatryFrontiers in Psychiatry 2024;15:1301976.Abstract
Background: Substance use is prevalent among people with mental health issues, and patients with psychosis are more likely to use and misuse substances than the general population. Despite extensive research on substance abuse among the general public in Kenya, there is a scarcity of data comparing substance use among people with and without psychosis. This study investigates the association between psychosis and various substances in Kenya.Methods: This study utilized data from the Neuro-GAP Psychosis Case-Control Study between April 2018 and December 2022. The KEMRI-Wellcome Trust Research Programme recruited participants from various sites in Kenya, including Kilifi County, Malindi Sub-County, Port Reitz and Coast General Provincial Hospitals, and Moi Teaching and Referral Hospital, as well as affiliated sites in Webuye, Kapenguria, Kitale, Kapsabet, and Iten Kakamega. The collected data included sociodemographic information, substance use, and clinical diagnosis. We used the summary measures of frequency (percentages) and median (interquartile range) to describe the categorical and continuous data, respectively. We examined the association between categorical variables related to psychosis using the chi-square test. Logistic regression models were used to assess the factors associated with the odds of substance use, considering all relevant sociodemographic variables.Results: We assessed a total of 4,415 cases and 3,940 controls. Except for alcohol consumption (p-value=0.41), all forms of substance use showed statistically significant differences between the case and control groups. Cases had 16% higher odds of using any substance than controls (aOR: 1.16, 95%CI: 1.05-1.28, p=0.005). Moreover, males were 3.95 times more likely to use any substance than females (aOR:3.95; 95%CI: 3.43-4.56). All the categories of living arrangements were protective against substance use.Conclusion: The findings of this study suggest that psychotic illnesses are associated with an increased likelihood of using various substances. These findings are consistent with those of previous studies; however, it is crucial to investigate further the potential for reverse causality between psychosis and substance abuse using genetically informed methods.
Moki C, Kigen G, Busakhala N. Effectiveness and Nephrotoxicity of Polymyxin B among Intensive Care Unit Patients: A Clinical Evaluation. African Journal of Pharmacy and Alternative Medicine 2024;3:85-92.Abstract
Polymyxin B is a reserve antibiotic, but there has been an upsurge in its use due to a rise in multidrug-resistant gram-negative bacteria. However, nephrotoxicity and resistance concerns persist, with global resistance rates reaching 29%. Effectiveness of Polymyxin B (clinical and microbiological response) and the frequency of nephrotoxicity is not well documented in resource limited settings. Research is essential to guide optimization of Polymyxin B therapy and inform the adoption of measures for early detection of kidney injury to prevent damage. This study aimed to assess the effectiveness of Polymyxin B by evaluating clinical and microbiological responses and determining nephrotoxicity incidence using KDIGO criteria in ICU patients at Moi Teaching and Referral Hospital (MTRH). A prospective observational cohort study was conducted at MTRH ICUs between December 2021 and November 2022, on patients treated with Polymyxin B. Data on demographics, comorbidities, Polymyxin B dosage regimens, clinical responses, and microbiological results were collected. Descriptive statistics summarized patient characteristics, while associations between dosage regimens and outcomes were evaluated using Fisher's exact test and multivariate regression, with a p<0.05 considered statistically significant. Forty-four patients with a mean age of 48 years were included; 66% were male, and cerebrovascular disease was the most common comorbidity. All patients had multidrug-resistant gram-negative infections qualifying for Polymyxin B therapy. Most (89%) received monotherapy, with 86% achieving a good clinical response, 7% experiencing treatment failure, and 7% dying. Doses of 20,000–25,000 IU/Kg/day were associated with microbiological eradication and good clinical response (p<0.001), while 15,000 IU/Kg/day was associated with treatment failure. Acute kidney injury occurred in 48% of patients, with 68% developing hypomagnesemia. Polymyxin B at doses of between 20,000-25,000IU/Kg/day should be considered as a starting dose due to the association with good clinical response, with alternate-day monitoring of serum creatinine levels for early detection of nephrotoxicity.
Kamoet J, Busakhala N, Kigen G. Incidence And Factors Associated With Dexmedetomidine Induced Hypotension And Bradycardia At Moi Teaching And Referral Hospital Intensive Care Unit Eldoret, Kenya. International Journal of Scientific and Research Publications 2024;14:78-83.Abstract
Background: Dexmedetomidine is the preferred drug for light sedation in intensive care units (ICU) where sedation plays an important role in patient comfort. Its advantages include shorter weaning time and earlier extubating from mechanical ventilation without respiratory depression. However, dexmedetomidine has been associated with over 50% incidence of hemodynamic adverse effects (hypotension and bradycardia) that has led to poor clinical outcomes. This limits its widespread use. Factors such as age, comorbidities, concomitant medications, dosage, baseline mean arterial pressure (MAP) and heart rate (HR) have been associated with adverse effects. Despite the high number of reported adverse effects, there is limited data on incidence and associated factors in resource limited settings. Therefore, its burden at Moi Teaching and Referral Hospital (MTRH) remains unknown. Knowledge on incidence and associated factors may inform future practice on safe use of dexmedetomidine at MTRH. Objective: To determine incidence and clinical factors associated with dexmedetomidine induced adverse effects among patients sedated with dexmedetomidine at MTRH ICU. Methods: This was a prospective observational study done at MTRH ICU. Hemodynamically stable eligible participants on dexmedetomidine were enrolled through census method between mid-April and mid-October 2022.The dependent variable was incidence of dexmedetomidine induced hemodynamic adverse effects. Data on MAP, HR were collected at selected time points within 24 hours. Independent variables which included factors such as age, gender, comorbidities, concomitant medication, renal, liver functions and drug dosages were obtained from patient records. Cutoff for hypotension was a MAP less than 60mmHg or a drop in MAP of 30% within the first hour, while bradycardia was a HR less than 60bpm or a drop in HR of 30% within first hour of drug administration. Continuous, data was summarized using means, medians and categorical data as frequencies and proportions. Fisher’s exact test and Kruskal Wallis test was used to assess for associations between categorical variables and continuous independent variables. The association between the clinical factors and development of dexmedetomidine induced hemodynamic adverse effects was analyzed using logistic regression model. Results: A total of 61 participants were recruited and 41% had traumatic brain injury. The mean age was 37 years and males were 63.9%. All participants had baseline HR>60bpm and MAP>60mmHg during drug initiation. Five patients (8.2%) developed hypotension and one (1.6%) developed bradycardia at the first hour. Mean baseline MAP was 90.49mmHg and mean decline was 5.16mmHg at 1hour. Mean baseline HR was 98.75bpm and mean decline was 0.91bpm within the first hour. Majority of patients received drug doses ranging from 0.2 to 0.7mcg/kg/hr for less than 24 hours. Lower baseline MAP <70mmHg was significantly associated with dexmedetomidine hemodynamic adverse effects (OR 2.17[95%CI 1.08-2.97, p<0.01]). However, there was no significant association between gender (0.21), baseline HR (0.88), comorbidities (0.19), concomitant medications (0.15), dose and duration (1), renal (0.28), liver functions (0.17) and occurrence of hemodynamic adverse effects. Conclusion: This study reported a low incidence of dexmedetomidine induced adverse effects compared to previous studies. Lower baseline MAP<70mmHg was an independent predictor of dexmedetomidine induced hypotension and bradycardia. Recommendations: Patients with lower baseline MAP<70mmHg and on dexmedetomidine should be monitored more frequently within the first hour.
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