Effect of glycerol and hyperosmolality on intracranial pressure

Potentially Harmful Excipients: State of the Art for Oral Liquid Forms Used in Neonatology and Pediatrics Units

The pediatric population exhibits an important age-dependent heterogeneity in pharmacokinetics and pharmacodynamics parameters, resulting in differences in drug efficacy and toxicity compared to the adult population, particularly for neonates. Toxicity and efficacy divergences have been studied for active molecules, but the impact on the pharmacological parameters of excipients remains less well known. To fill this lack of knowledge, several initiatives have been started to gather information on the specific toxicity of excipients, such as the KIDS list or the STEP database. In order to contribute to this much-needed action, in this work, a compilation of the 219 formulations of oral liquid forms prescribed in pediatrics and neonatology units was established based on the summary of product characteristics. Then, for excipients found in more than 10% of the analyzed formulations, a review of their toxicity data was carried out using the STEP database. Finally, for a selection of 10 frequently used liquid forms, the amounts of excipients administered daily were calculated based on the recommended posology in the Summary of Product Characteristics (SPC) and compared with the recommended daily limits proposed by the European Medicine Agency. Pediatrics-adapted formulations are still rare, and it is not always possible to find safe alternatives to drugs containing excipients of interest.

Comparative efficacy and safety of glycerol versus mannitol in patients with cerebral oedema and elevated intracranial pressure: A systematic review and meta-analysis

WHAT IS KNOWN AND OBJECTIVE

Glycerol is thought to be superior to mannitol in the treatment of cerebral oedema and elevated intracranial pressure (ICP), particularly with safety concerns. However, the current evidence remains insufficient. Therefore, we aimed to compare the efficacy and safety of glycerol versus mannitol in this meta-analysis.

METHODS

PubMed, EMBASE, Web of Science, CENTRAL, China National Knowledge Infrastructure, Wanfang Database, Chongqing VIP information, ClinicalTrials.gov, and the reference lists of relevant articles were searched for randomized controlled trials comparing glycerol and mannitol in patients with brain oedema and elevated ICP. Two investigators independently identified the articles, assessed the study quality and extracted data. Data analyses were performed using RevMan software.

RESULTS AND DISCUSSION

Thirty trials involving 3144 patients met our inclusion criteria. Pooled data indicated that glycerol and mannitol had comparable effectiveness in controlling cerebral oedema (RR, 1.00; 95% CI, 0.97 to 1.03; p = .97), but the risks of acute kidney injury and electrolyte disturbances were significantly lower with glycerol (RR, 0.21; 95% CI, 0.16 to 0.27 and RR, 0.23; 95% CI, 0.17 to 0.30, respectively) than mannitol. Moreover, there seemed to be a lower probability of rebound ICP after the withdrawal of glycerol. Neither haemolysis nor elevated blood glucose levels were observed in the glycerol group.

WHAT IS NEW AND CONCLUSION

Regarding the balance between efficacy and safety, glycerol could be an effective and more tolerable alternative therapy for cerebral oedema and elevated ICP than mannitol, especially for high-risk populations of renal failure.

A review of the metabolism of 1,4-butanediol diglycidyl ether-crosslinked hyaluronic acid dermal fillers

BACKGROUND

Cosmetic procedures are growing ever more common, and the use of soft tissue fillers is increasing. Practicing physicians need to be aware of the biological behavior of these products in tissue to enable them to respond to any safety concerns that their patients raise.

OBJECTIVES

To provide an overview of the metabolism of 1,4-butanediol diglycidyl ether (BDDE)-crosslinked hyaluronic acid (HA) dermal fillers and to examine the safety of the resulting byproducts.

METHODS

A review of available evidence was conducted.

RESULTS

After reaction with HA, the epoxide groups of BDDE are neutralized, and only trace amounts of unreacted BDDE remain in the product (<2 parts per million). When crosslinked HA, uncrosslinked HA, and unreacted BDDE degrade, they break down into harmless byproducts or into byproducts that are identical to substances already found in the skin.

CONCLUSION

Clinical and biocompatibility data from longer than 15 years support the favorable clinical safety profile of BDDE-crosslinked HA and its degradation products. Given the strength of the empirical evidence, physicians should be confident in offering these products to their patients.

Glycerol adjuvant therapy in adults with bacterial meningitis in a high HIV seroprevalence setting in Malawi: a double-blind, randomised controlled trial

BACKGROUND

Southern Africa has a high incidence of bacterial meningitis in adults, often associated with HIV co-infection. Mortality exceeds 50%, even with appropriate antibiotic therapy, and is not improved with corticosteroids. Glycerol adjuvant therapy reduces long-term morbidity in bacterial meningitis in children, and its use is being promoted. We aimed to assess the effectiveness of glycerol as an adjuvant therapy for adults with bacterial meningitis in Africa.

METHODS

The study was done in two phases. First, in an open-label dose-finding study, 45 adult patients with symptoms, signs, and cerebrospinal fluid findings consistent with bacterial meningitis received either 50 mL, 75 mL, or 100 mL of glycerol four times a day for 4 days. We then did a randomised, double-blind, placebo-controlled trial of oral glycerol in adults with bacterial meningitis. Patients with clinical and cerebrospinal fluid findings suggestive of bacterial meningitis were randomly assigned in blocks of 12 by use of a random number list produced by an independent statistician to receive either glycerol or an equivalent volume of sugar solution. Glycerol and placebo were indistinguishable by colour or taste. The primary outcome was mortality at 40 days, with secondary outcomes including disability and mortality restricted to pneumococcal disease. All patients were analysed for the primary outcome excluding those who were lost to follow-up. This trial is registered at controlled-trials.com, number ISRCTN70121840.

FINDINGS

75 mL glycerol four times a day was the highest tolerated dose, and was used for the main study. 265 patients were assigned treatment: 137 glycerol and 128 placebo. The trial was stopped early on the advice of the data and safety monitoring board after a planned interim analysis. By day 40, 61 (49%) of 125 patients in the placebo group and 86 (63%) of 136 in the glycerol group had died (adjusted odds ratio 2.4, 95% CI 1.3-4.2, p=0.003). There was no benefit from glycerol for death and disability by day 40, and glycerol did not improve death and disability by day 40 or death at day 40 in patients with proven bacterial disease or pneumococcal disease. Two serious adverse events occurred that were possibly due to the study drug.

INTERPRETATION

Oral glycerol therapy cannot be recommended as an adjuvant therapy in adults with bacterial meningitis in resource-poor settings with a high HIV prevalence.

FUNDING

Meningitis Research Foundation.

The diagnosis and management of acute bacterial meningitis in resource-poor settings

Acute bacterial meningitis is more common in resource-poor than resource-rich settings. Survival is dependent on rapid diagnosis and early treatment, both of which are difficult to achieve when laboratory support and antibiotics are scarce. Diagnostic algorithms that use basic clinic and laboratory features to distinguish bacterial meningitis from other diseases can be useful. Analysis of the CSF is essential, and simple techniques can enhance the yield of diagnostic microbiology. Penicillin-resistant and chloramphenicol-resistant bacteria are a considerable threat in resource-poor settings that go undetected if CSF and blood can not be cultured. Generic formulations of ceftriaxone are becoming more affordable and available, and are effective against meningitis caused by penicillin-resistant or chloramphenicol-resistant bacteria. However, infection with Streptococcus pneumoniae with reduced susceptibility to ceftriaxone is reported increasingly, and alternatives are either too expensive (eg, vancomycin) or can not be widely recommended (eg, rifampicin, which is the key drug to treat tuberculosis) in resource-poor settings. Additionally, improved access to affordable antibiotics will not overcome the problems of poor access to hospitals and the fatal consequences of delayed treatment. The future rests with the provision of effective conjugate vaccines against S pneumoniae, Haemophilus influenzae, and Neisseria meningitides to children in the poorest regions of the world.

Glycerol dehydrates oedematous as well as normal brain in dogs

1. Although the effect of glycerol on reducing intracranial pressure has been widely investigated, only a few studies have reported its dehydrating effect on brain oedema caused by infarction, ischaemia, microembolism and cold injury, but none on traumatic oedema. In this study the effects of glycerol (1 g/kg, i.v. bolus infusion at a rate of 0.04 g/kg per min) on traumatic and cryogenic cerebral oedema and on normal brain were compared in the anaesthetized dog. The tissue water content was measured with the gravimetric method. 2. Oedema resulting from mechanical trauma was initiated 4 h prior to treatment with glycerol (8 dogs) or vehicle (5 dogs) by closed head contusion with fixed force under general anaesthesia. Tissue samples underneath the region of contusion were taken, before and 1 h after infusion of glycerol or vehicle, for the measurement of water content. 3. Glycerol infusion decreased the water content in white matter of the traumatic brain model from 76.54 +/- 1.70% to 70.73 +/- 1.54% (P < 0.001). In normal brain the reduction was from 68.42 +/- 0.48% to 65.36 +/- 0.39% (P < 0.001). Neither vehicle nor glycerol infusion resulted in significant changes in specific gravity of the gray matter. 4. Cryogenic oedema was initiated 3 h prior to the infusion of glycerol or vehicle by applying unilaterally a brass conical cup (bottom diameter 1 cm) filled with dry ice-acetone (-65 degrees C) to the exposed dura for 1 min. The contralateral hemisphere, which was not subjected to cold injury, was used for determination of water content of normal gray and white matter. 5. Glycerol infusion decreased the water content in the white matter of the cold-injured region from 75.38 +/- 0.69% to 72.57 +/- 0.58% (P < 0.001). In the normal white matter the reduction was from 68.63 +/- 0.34% to 65.48 +/- 0.49% (P < 0.001). 6. Our data indicate that glycerol decreases water content of the white matter in traumatic and cold-injured oedematous brain as well as in normal brain.

Relationships between dopamine infusions and intracranial hemodynamics in patients with raised intracranial pressure

Dopamine, 1-10 micrograms/kg body weight/min was infused in 6 patients suffering from cerebrovascular diseases with elevated intracranial pressure and a critical cerebral perfusion pressure. Dopamine decreased intracranial pressure in 3 and increased it moderately in the other 3 patients. In all patients, the dopamine-induced rise of mean arterial pressure led to an increase of cerebral perfusion pressure. Transcranial Doppler ultrasonographic recordings of the middle cerebral artery in patients whose intracranial pressure declined revealed a decrease of the pathologically elevated cerebrovascular resistance, and an augmentation of cerebral blood supply. In conclusion, dopamine infusions may improve cerebral hemodynamics in some patients with severe brain edema. Such patients can be identified by intracranial pressure and Doppler monitoring.

Temporary reversal of serum to cerebrospinal fluid glycerol concentration gradient after intravenous infusion of glycerol

Glycerol 50 g infused i.v. over 2 to 6 h is widely used to treat cerebral oedema in patients with acute stroke. Its transit through the blood-cerebrospinal fluid barrier in subjects with uninflamed meninges has now been examined. In 7 patients with an external ventriculostomy for occlusive hydrocephalus, each of whom was given 500 ml of a 10% solution IV over 4 h, serum and CSF were repeatedly sampled during and after the infusion and glycerol was measured enzymatically. The highest serum glycerol level of 191-923 mg/l was observed at the end of the infusion. The maximum CSF glycerol of 18.7-110.8 mg/l was attained 0-1 h after the end of the infusion. Elimination both from serum and CSF approximated a single-exponential decay; the elimination half-life from serum was 0.29-0.56 h compared to 1.03-3.68 h from CSF. In six of the seven cases there was a temporary reversal of the serum/CSF concentration gradient during glycerol elimination. The ratios of the AUCs of CSF and serum, which describe the overall penetration of glycerol into CSF, ranged from 0.09-0.31. In conclusion, the serum level of glycerol produced by giving 50 g IV glycerol over 4 h may not be sufficiently high reliably dehydrate to brain tissue in many patients, and the slow elimination of glycerol from the CSF may be related to the so-called rebound phenomenon.

Clinical pharmacokinetic considerations in the treatment of increased intracranial pressure

Life-threatening increased intracranial pressure can be reversed by a variety of drugs. These compounds all have some disadvantages, producing rebound effects, severe coma or cardiovascular depression and electrolyte imbalance. However, reduction of intracranial pressure is a prerequisite for recovery and the benefits of treatment outweigh the risks. Dexamethasone is rapidly eliminated, the short half-life (about 3 hours) indicating that dosage intervals should be kept small. As yet, however, its therapeutic efficacy has not been clearly demonstrated. Therefore, an association between pharmacokinetics and pharmacodynamics cannot be established. Osmotic diuretics are the most widely used agents for reduction of intracranial pressure. Pharmacokinetics show a very close relationship to changes in serum osmolality, but there are large variations in the clearance. For the use of osmotics, the blood-brain barrier must be intact. Osmotic diuretics may lead to intracerebral oedema or to acute renal failure as serum osmolality increases. Considering the pharmacokinetics of each drug, and the dynamics of intracerebral pressure and osmolality, an intermittent, individually titrated dosage should be administered, with simultaneous monitoring of intracranial pressure. Frusemide (furosemide) can be used as an adjunct, to enhance the effect of osmotic diuretics. Its pharmacokinetics are limited by renal function, depending on age as well as on the extent of renal impairment. Altered renal elimination of concomitantly administered drugs, and electrolyte imbalances should be anticipated when diuretics are used. Barbiturates are certain to decrease intracranial pressure in humans by an as yet unknown mechanism. Their administration is recommended for patients that do not respond to conventional therapy. As barbiturates can result in deep coma, knowledge of their pharmacokinetics is of great importance for recovery. Following single doses, pentobarbitone has a relatively long elimination half-life (about 22 hours). However, after repeated administration for several days, its elimination may be enhanced due to autoinduction. Thiopentone kinetics are characterised by distribution and redistribution into deep peripheral compartments. Administration of high and frequent doses leads to considerably delayed recovery. This is not true for methohexitone, which shows comparable pharmacokinetics after single and multiple dose administration. Elimination depends on liver blood flow. Thus, recovery from methohexitone-coma is rapid. Rapid elimination is also an important characteristic of etomidate and alphaxalone/alphadolone, two non-barbiturate hypnotics.(ABSTRACT TRUNCATED AT 400 WORDS)

Acute effect of glycerol on net cerebrospinal fluid production in dogs

The effect of glycerol administration on cerebrospinal fluid (CSF) formation in dogs was studied by means of a ventriculocisternal perfusion technique. Net CSF production rate decreased after oral administration of glycerol (3 gm/kg) from a baseline level of 42.33 +/- 6.68 microliter/min (mean +/- standard error) to a trough of 10.33 +/- 4.88 microliter/min at 90 minutes after administration (p less than 0.025). Serum osmolality concomitantly increased from a baseline value of 296 +/- 2.83 to 309 +/- 4.7 mOsm/kg H2O at 90 minutes. The mean percentage change in CSF production inversely correlated to the mean percentage change in serum osmolality, r = -0.85. Thus, glycerol administration decreases net CSF formation, and this effect may be related in part to the rise in serum osmolality.

Pharmacologic management of acute intracranial hypertension

Acute intracranial hypertension requires aggressive treatment with physiologic and pharmacologic measures guided by intracranial pressure monitoring devices. Therapy involves the use of diuretics, corticosteroids, and barbiturates in combination with hyperventilation, ventricular drainage, and general supportive measures. This review focuses on the pathophysiology of increased intracranial pressure and the pharmacologic agents used in its management.