Pharmacokinetics and Pharmacodynamic Target Attainment of Benzylpenicillin in an Adult Severely Ill Sub-Saharan African Patient Population

Background

In intensive care (ICU) patients, systemic exposure of β-lactam antibiotics can be altered, and positive clinical outcome is associated with increasing fT > MIC ratios. In sub-Saharan African hospitals, benzylpenicillin (PEN) is frequently used for the empiric treatment of severe pneumococcal infections. Pharmacokinetic data for non-ICU hospitalized populations are lacking.

Methods

We performed a population pharmacokinetic (PPK) study in an adult Mozambican hospital population treated intravenously with PEN from October 2014 through November 2015. Four blood samples/patient were collected for total PEN (PENt) and unbound PEN (PENu) concentration measurement. We developed a PPK model through nonlinear mixed-effects analysis and performed simulations for different patient variable, dosing, and pharmacodynamic target scenarios.

Results

One hundred twelve participants yielded 387 PENt and 53 PENu concentrations. The median body mass index was 18.3 (range, 10.5-31.3) kg/m2 and the median albumin concentration and creatinine clearance (CrCl) were 29 (range, 12-44) g/L and 80 (range, 3-195) mL/minute, respectively. In a 1-compartment model, CrCl was positively correlated with PENt clearance. For infections with a microorganism with a minimum inhibitory concentration (MIC) of 1 mg/L, simulations demonstrated that with 3 million IU (1.8 g) every 6 hours, 74.1% would have a PENu concentration greater than the MIC during half of the dosing interval (fT > MIC = 50%), whereas this was 24.8% for the fT > MIC = 100% target. For pathogens with an MIC of 0.06 mg/L, these percentages were 98.2% and 72.3%, respectively.

Conclusions

Severely ill adult sub-Saharan African patients may be at high risk for underexposure to PENu during routine intermittent bolus dosing, especially when their renal function is intact and when infected with pathogens with intermediate susceptibility.

[The semiology and classification of myoclonias]

Myoclonus can present itself in various distinct clinical contexts. The authors review the possible different types of myoclonus, as a single manifestation or included in a syndrome, based on a semiological and aetiological classification. Special emphasis is given to the group of progressive myoclonus epilepsies.

[Prefrontal syndrome as a manifestation of intracranial dural arterio-venous malformation]

The authors present a clinical case of an intracranial dural arteriovenous malformation with clinical manifestations of a prefrontal syndrome, documented with its respective diagnostic tests, including imaging studies. A number of considerations are being enlarged upon, concerning possible pathophysiological mechanisms.

[Cerebrovascular disorders in young subjects and deficit of protein S]

The authors describe a right hemiparesis and global aphasia, suddenly developed in a 33-Year-old woman, with a previous aphasia, 7 years ago, from which she recovered without sequels. They discuss the relationship between protein inhibitor of blood coagulation and arterial thrombosis, and make references to what has been published about it.

[Familial peripheral neuropathy caused by susceptibility to entrapment (tomaculous neuropathy)]

The authors describe a case of hereditary neuropathy with liability to pressure palsies (entrapment), and compare it to reports from literature. The main characteristics are: autosomal dominant inheritance, recurrent mononeuropathies (ulnar, median, peroneal, brachial plexus), and specific features at nerve biopsy. The sensory nerve reveals predominantly demyelinating alterations, having the remaining myelin fibres focal thickenings, the so called tomaculous, and shows numerous subperineural structures named Renaut Bodies. The EMG findings show a slowing of the nerve conduction velocities and an increase of distal latencies.