Paediatric drug development: the impact of evolving regulations

Children deserve medicines that are adapted to their needs. The need to include children in drug development has been recognised increasingly over the past few decades. Legal and regulatory frameworks are well established in the EU and US. The amount of work done to study medicines for children is significantly greater than it was 10 years go. Proof-of-concept has been demonstrated for all segments of the paediatric drug development pipeline. It is now time to examine how the practice of developing medicines for children has evolved within those frameworks and to determine how that work should be generalised. This review describes the development of medicines for children and critically appraises the work that has been done within those frameworks. Significant effort is needed to realize the potential provided by the current regulatory framework. Using the work programme of the Global Research in Paediatrics (GRiP) Network of Excellence as a template we outline current work and future growing points.

Medicines for children licensed by the European Medicines Agency (EMEA): the balance after 10 years

OBJECTIVE

The 1995-2005 balance of EMEA activities in the field of paediatric medicines was evaluated, taking into account the number both of drugs authorised for children and paediatric studies supporting the Marketing Authorisation (MA).

METHODS

Data on drugs authorised by EMEA were extracted from EPARs (European Public Assessment Reports). Active substance, year of approval, anatomical, therapeutic and chemical (ATC) code, indication, orphan status, ages, and registrative clinical studies characteristics were assessed.

RESULTS

The percentage of authorised substances for paediatrics is 33.3%. This percentage decreased or increased when different subsets of medicines were considered [medicines for children under 2 years (23.4%), N-ATC code drugs (6%) and orphan drugs (46.4%)]. A total of 165 trials were included in the MA dossiers of 51 drugs at the time of approval, and additional 22 studies were added to the dossiers of 12 active substances submitted for paediatric variations. PK and Efficacy/Safety studies were performed for 32 (52%) active substances, while either one PK or one Efficacy/Safety study was carried out for 43 (69%) and 45 (73%) substances, respectively.

CONCLUSIONS

This report demonstrates that the total number of paediatric medicines approved by EMEA is stable over the 10-year period, while an increase in drugs to treat serious or orphan diseases has been observed. In addition, under the Centralised Procedure, a valuable number of paediatric trials have been submitted to support drug approval.

Medicines for children licensed by the European Agency for the Evaluation of Medicinal Products

OBJECTIVE

. The aim of this study was to evaluate the number and the characteristics of medicines approved for children in Europe by the European Agency for the Evaluation of Medicinal Products (EMEA) and whether the paediatric studies supporting the authorisation were in accordance with the Note for Guidance on the Clinical Investigation of Medicinal Products in children (CPMP/ICH/2711/99). We also considered any possible difference between the EMEA and the Food and Drug Administration (FDA) paediatric medicines evaluations.

METHODS

. We examined the drugs authorised by the EMEA through the centralised procedure from January 1995 to September 2001 deriving information from the "European Medicines - Database" (EMD) set up in 1998 by the Italian Group for Pharmacoeconomic Studies (GISF) and sponsored by the Italian Ministry of Health. The analysis of paediatric data has been managed by experts belonging to the Clinical Pharmacology Working Group of the Italian Paediatric Society. The following parameters were assessed: active substance, year of approval, anatomical therapeutic and chemical (ATC) code, therapeutic indications, age for which the drug is authorised, interest to children and paediatric studies supporting a paediatric authorisation. European Public Assessment Reports (EPARs) were considered as reference sources.

RESULTS

. The median percentage of drugs authorised for children from 1995 to 2001 (September) is 35% of the total of commercially available drugs; only 16 medicines have been approved for children under 2 years of age (11%), ten of these being vaccines. Medicines for children shared out 9 ATC classes, 24 belonging to the J- (anti-infective agents) -ATC class. Thirty-nine medicines were authorised on the basis of at least one clinical trial (27 phase III, 6 phase II, 6 phase I) while eight active substances have been licensed without any paediatric investigation.

CONCLUSIONS

. Under the EMEA centralised procedure, several active substances have been licensed for children. Consequently serious and life-threatening diseases as AIDS and diabetes are now treatable, in a legal framework overcoming the orphan status of the past years. Despite the reported encouraging results, the number of drugs devoted to children remain low and important ATC classes, as L-(oncology) or N-(neurology), are still 'orphans' of innovative medicines. At the same time few medicinal products are specifically studied in children. Consequently, more efforts have to be made to increase the number of drugs assessed and licensed for the paediatric population, and manufacturers should be required to supply data on the effects of new drugs in children when the products are expected to offer a benefit over existing therapies.

Energy expenditure and nutritional adequacy of rehabilitation paraplegics with asymptomatic bacteriuria and pressure sores

OBJECTIVE

To measure resting energy expenditure (REE) in a group of people with postacute paraplegia, quantify the impact of asymptomatic bacteriuria and pressure sore(s) on patients' metabolic rate, and estimate the adequacy of patients' nutritional intakes to preserve patients' protein levels.

MATERIAL AND METHODS

Ten males with post-acute paraplegia aged 42.1+/-18.7 years. We evaluated: height, body mass index (BMI), resting energy expenditure (REE), total daily calorie requirement (E), 24-h urine creatinine excretion (Cru), creatinine index (CI), and nitrogen balance (NB).

RESULTS

Subjects with paraplegia showed high erythrocyte sedimentation rates. As a group, they had normal resting calorie consumption when REE was normalized for unit of urine creatinine (REE/Cru), it was higher in patients than in controls. Six of the 10 patients had a low calorie intake: of these only three had a negative nitrogen balance.

CONCLUSION

In conclusion, the resting energy expenditure of the subjects with significant bacteriuria and pressure sore(s) of 23.7 kcal/kg/day suggests that a large portion of patients may have an inadequate calorie protein intake to preserve their nutritional status. The clinical significance of this study is that 28.5 kcal/kg/day may be the lower calorie threshold to meet the metabolic demands of people with apyretic paraplegia with bacteriuria and pressure sore(s).

The effects of aging on enzyme activities and metabolite concentrations in skeletal muscle from sedentary male and female subjects

Aging affects the metabolic capacity of skeletal muscle, in particular the glycolytic and respiratory capacities. The purpose of this study was to quantify biochemical alterations due to aging in muscular metabolic capacity in human skeletal muscles in sedentary subjects. The activities of various marker enzymes and metabolites related to glycolysis, Krebs' cycle and the electron transfer chain and high energy phosphate compounds were measured in muscle biopsies from the rectus abdominis, vastus lateralis, and gluteus maximus muscles of 76 sedentary subjects (32 males and 44 females) between 15 and 91 yr. No significant differences between males and females were found, but changes related to age were: a decrease in hexokinase and lactate dehydrogenase activities in the rectus abdominis; a decrease in citrate synthase activity and citrate in the vastus lateralis; an increase in pyruvate kinase activity and a decrease in ATP and creatine phosphate concentrations in the gluteus maximus. These data suggest that distinct muscles may respond differently to aging regardless of sex in sedentary subjects.

Peripheral plasma amino acid abnormalities in rehabilitation patients with severe brain injury

OBJECTIVE

Acute severe brain injury causes an increased mobilization of amino acids from tissue. The plasma amino acid profile of patients undergoing rehabilitation after brain injury is unknown. This study was aimed at delineating the plasma amino acid profile of rehabilitation patients with brain injury.

DESIGN

Peripheral plasma aminogram, lactate, pyruvate, glycerol, ketone body, and carnitine concentrations were determined in 11 patients with brain injury (34.6+/-15 years old, 60+/-16.8 days after injury) and in 8 controls. Resting energy expenditure and nitrogen balance were also determined.

RESULTS

(1) All essential amino acids and about 50% of nonessential amino acids were significantly lower in brain injury patients than in controls (p < .05). (2) Plasma amino acids were lower irrespective of either energy and protein intake or nitrogen balance. (3) Total carnitine concentration and esterified/free carnitine ratio were higher in brain injury patients than in controls (p < .05).

CONCLUSIONS

Rehabilitation patients with brain injury may have an important reduction of their plasma aminogram. Muscle tissue depletion and the persistence of a hypercatabolic state caused by subclinical infections, pressure sores, and immobility may contribute to this reduction.

Despite good compliance, very low fat diet alone does not achieve recommended cholesterol goals in outpatients with coronary heart disease

AIM

A low-saturated, low-cholesterol diet is important in the treatment of hypercholesterolaemia in patients with coronary heart disease. The aim of this study was to investigate the efficacy of a very low fat diet to achieve a targeted serum low density lipoprotein (LDL) cholesterol level (</=2.59mmol x l-1) in outpatients with coronary heart disease.

METHODS

One hundred and twenty-six male patients (all ex-smokers) with coronary heart disease and a serum LDL cholesterol >3.37mmol x l-1 were investigated 12-14 weeks after an acute coronary event. After overnight fasting each patient had (a) his resting energy expenditure measured (indirect calorimetry using standard protocol) and (b) venous blood sampled from a forearm vein to determine lipid profile. All the patients were randomly allocated to four groups of treatment: Group A on a very low fat diet (resting energy expenditure-fat diet, where fat intake was </=20% resting energy expenditure): Group B on a low fat diet from the National Cholesterol Education program (National Cholesterol Education Program step 2 diet): Group C on resting energy expenditure-fat diet+simvastatin 10mg daily; Group D on National Cholesterol Education Program step 2 diet+simvastatin 10mg daily. For all patients the prescribed energy intakes were equal to their respective resting energy expenditures.

RESULTS

At 6 months, the average decrease in serum LDL cholesterol was not different between Group A and Group B, but the increase in high density lipoprotein cholesterol (HDL) (+29%) observed in Group A led to a reduced LDL cholesterol/HDL cholesterol ratio (P<0.001). As expected, a more important serum lipid improvement was found in the groups supplemented with diet+drug association, but the decrease in LDL cholesterol was higher in Group C than in Group D (-37+/-9.7% vs -24. 5+/-15%;P<0.00001) as well as LDL cholesterol/HDL cholesterol ratio (P<0.001). No patient on diet alone achieved the recommended LDL cholesterol level </=2.59mmol x l-1.

CONCLUSION

Diet alone does not allow patients with coronary heart disease to achieve the recommended blood cholesterol levels, even if its fat content is highly reduced.

Free radical activity following contraction-induced injury to the extensor digitorum longus muscles of rats

The purpose of the study was to investigate the role of free radicals in the injury induced by a protocol of repeated pliometric (lengthening) contractions to the extensor digitorum longus (EDL) muscle in situ in rats. Previous data have indicated that prior treatment with the antioxidant polyethylene glycol-superoxide dismutase reduced the damage that was apparent at 3 days following this type of exercise. Three hours and 3 days following the protocol, the magnitude of the semiquinone-derived free radical signal observed by electron spin resonance spectroscopy (ESR) was not different for exercised and non-exercised skeletal muscles. A reduction in the protein thiol content of muscle was evident at 3 h, and was still apparent at 3 days. Three hours after the protocol, the total muscle glutathione content and the percentage in the oxidized form were unchanged, but by 3 days the percentage of muscle glutathione present in the oxidized form was elevated. The susceptibility of muscle to lipid peroxidation in vitro was reduced 3 days after the pliometric contractions. These data indicate that oxidation of protein thiols and glutathione may be involved in the secondary damage following pliometric contractions, but provide no evidence that the species involved were derived from mitochondrial semiquinone radicals.

Effect of propylthiouracil-induced hypothyroidism on the onset of skeletal muscle necrosis in dystrophin-deficient mdx mice

1. Duchenne and Becker muscular dystrophies are X-linked disorders caused by defects in muscle dystrophin. The mdx mouse is an animal model for Duchenne muscular dystrophy which has a point mutation in the dystrophin gene, resulting in little (<3%) or no expression of dystrophin in muscle. Mdx mice show a characteristic pattern of muscle necrosis and regeneration. Muscles are normal until the third postnatal week when widespread necrosis commences. This is followed by muscle regeneration, with the persistence of centrally nucleated fibres. 2. This work has examined the hypothesis that the onset of this muscle necrosis is associated with postnatal maturation of the thyroid endocrine system and that pharmacological inhibition of thyroid hormone synthesis delays the onset of muscle necrosis. 3. Serum T4 and T3 concentrations of mice were found to rise immediately before the onset of muscle necrosis in the mdx mouse, and induction of hypothyroidism by treatment of animals with propylthiouracil was found to delay the onset of muscle necrosis. 4. The results provide the first demonstration of experimental delay of muscle necrosis by manipulation of the endocrine system in muscle lacking dystrophin, and provide a novel insight into the way in which a lack of dystrophin interacts with postnatal development to precipitate muscle necrosis in the mdx mouse.

Metabolite concentrations in skeletal muscle of different aged rats submitted to hypoxia and pharmacological treatment with nicergoline

The energy metabolism of the gastrocnemius and soleus muscles in young-adult, mature, and senescent rats was evaluated after 72 h of continuous exposure to normobaric hypoxia or normoxia. The effects of treatment with the alpha-adrenergic antagonist nicergoline were also investigated. In the gastrocnemius muscle we evaluated the concentrations of some significative metabolites involved in anaerobic glycolysis and the Krebs' cycle, free amino acids related to the Krebs' cycle, ammonia, some energy mediators, and the energy store creatine phosphate. In the soleus muscle a selection of these was evaluated. In both muscles aging was similarly characterized by a decrease in muscular creatine phosphate concentration, while the energy mediators and the energy charge potential remained unchanged. Singly, some gastrocnemius muscle metabolites showed linear changes in their concentrations with aging, while for the soleus muscle the only linear change regarded glucose-6-phosphate. Continuous normobaric hypoxia induced greater changes at the age of 4 and 24 months than at 12 months. Chronic treatment with nicergoline modified the influence of hypoxic conditions on muscle metabolites concentrations only in some cases, regardless of the age of the animals. Further investigations are necessary before any firm conclusions can be drawn about the pharmacological activity of nicergoline on hypoxia in aged rats.

Effect of L-carnitine on myocardial metabolism: results of a balanced, placebo-controlled, double-blind study in patients undergoing open heart surgery

The effects of L-carnitine on cardiac performance after open heart surgery were evaluated in a balanced, placebo-controlled, double-blind study in 38 patients. Preoperative haemodynamic status was good in all of them. Seventeen subjects underwent mitral valve replacement and 19 patients coronary artery bypass grafting. Five grams L-carnitine were given intravenously over 2 h, twice daily for 5 consecutive days; moreover, 10 g L-carnitine in 1500 ml cardioplegia were administered through the aortic root after aortic cross-clamping. Surgery was always planned on treatment day 3. The post-ischaemic functional recovery of the heart was assessed by clinical parameters, as well as by biochemical and ultrastructure evaluations on biopsy specimens. No differences were found between the control and the treatment group with respect to all clinical parameters of cardiac performance after cardiopulmonary bypass. At anaesthesia induction, serum carnitine was significantly increased in treated patients, but carnitine concentrations in the right atrial biopsy obtained just before aortic declamping were similar in the two groups. In patients with mitral valve replacement, L-carnitine therapy was associated with significantly higher concentrations of pyruvate, ATP and creatine phosphate in papillary muscle. Glycogen levels were also higher in the treated group, but the difference was not statistically significant. Myocardial ultrastructure on septal biopsies, obtained within 5 min from weaning from extracorporeal circulation, showed better preservation scores for all considered parameters (nucleus, sarcoplasmic reticulum, mitochondria and cellular oedema) in the treated subjects, although the difference reached statistical significance only for nuclei. When biochemical and ultrastructural data are considered, these findings suggest that L-carnitine improves myocardial metabolism. However, it cannot be concluded that L-carnitine provides an advantageous support therapy for well-compensated patients requiring cardiac surgery. In contrast, the positive effects of L-carnitine on cardiac recovery after bypass might become clinically relevant in the surgical setting for haemodynamically compromised patients, in which further investigations are required.

Altered muscle energy metabolism in post-absorptive patients with chronic renal failure

Skeletal muscle biopsies were performed on 12 healthy sedentary subjects and on 22 non-dyalized chronic renal failure patients (CRF) on a free diet and after overnight fasting. Parathormone, glucagon and insulin were determined at the same time of biopsies. CRF patients showed significantly low ATP and creatine phosphate levels. Regarding enzyme activities, a high hexokinase Vmax was found, while the pyruvate kinase activity was lower than in the control group. For the tricarboxylic acid cycle, citrate synthase, succinate dehydrogenase and malate dehydrogenase activities were higher; total NADH cytochrome c reductase activity was also high, while cytochrome oxidase activity was slightly lower. Both alanine aminotransferase and aspartate aminotransferase activities were considerably high in comparison with the control group. In conclusion, our study revealed a hypermetabolic TCA cycle, but impaired oxidative phosphorylation, which partly explained the reduced ATP concentration. Excessive protein intake and hormonal derangements may play a role in these metabolic changes.

Biochemical analysis of muscle biopsy in overnight fasting patients with severe chronic heart failure

To better characterize the role of skeletal muscle in chronic heart failure we studied energetic charge, metabolites and enzyme activity in the energy production pathway. We selected 15 males with severe chronic heart failure (NYHA class III, stable clinical conditions and in normal nutritional status) and seven controls. Controls and patients were submitted to biopsy of the vastus lateralis muscle in resting and fasting conditions. Hormone profiles were also evaluated. Our results showed near normal ATP, ADP and AMP concentrations, but there were substantially more reductions in glycogen (46 +/- 5 vs 77 +/- 6 mumoles glycosidic units.g-1 fresh tissue) and creatine phosphate (5 +/- 1 vs 13 +/- 1 mumoles.g-1 fresh tissue) in patients than in controls. We also found a reduction in glycolytic activity (pyruvate kinase 1009 +/- 79 vs 1625 +/- 26 nmoles. min-1.mg protein-1), despite normal tricarboxylic acid cycle velocity, an increase in alanine amino-transferase (964 +/- 79 vs 425 +/- 34 nmoles. min-1.mg protein-1) and in aspartate aminotransferase (515 +/- 44 vs 291 +/- 56 nmoles.min-1.mg protein-1). An increase was also observed in total NADH cytochrome c reductase (128 +/- 14 vs 68 +/- 5 nmoles.min-1.mg protein-1), while cytochrome oxidase activity was normal. The cortisol/insulin ratio was slightly elevated (77 +/- 4 vs 32 +/- 12). In conclusion, normonutritive patients with severe heart failure show an imbalance in the energy production/utilization ratio. The impairment is probably due both to a decrease in production and an increase in consumption of energy owing to greater cellular workload and/or a hypercatabolic state.

Pyruvate dehydrogenase deficiency in a child responsive to thiamine treatment

We report the clinical features in a 4-year-old child who was investigated for a suspected metabolic disorder but was subsequently diagnosed as having a pyruvate dehydrogenase deficiency. A muscle biopsy was performed and the data obtained suggested thiamine treatment which resulted in a regression of the clinical findings and a return to normal values of blood lactic and pyruvic acids. The interruption of thiamine supplementation after 1 year of treatment led to a prompt recurrence of the previous clinical and biochemical symptoms.

Instrumental and metabolic evaluation of patients affected by peripheral arterial occlusive disease (PAOD) following surgical revascularization surgery

Experiments were performed on eight subjects affected by peripheral arterial occlusive disease (PAOD) of the lower limbs. Each patient was submitted to Ecodoppler, angiography and the "Treadmill test". Two bioptic muscle of these patients. A sample was used for the spectrophotometric and spectrophotofluorimetric determinations of: glycogen, pyruvate, lactate, citrate, alpha-ketoglutarate, malate, aspartate, glutamate, AMP, ADP, ATP and creatine phosphate (CP). The other bioptic sample was used to determine the following enzyme activities: hexokinase, phosphofructokinase, pyruvate kinase, lactate dehydrogenase, citrate synthase, succinate dehydrogenase, malate dehydrogenase, total NADH cytochrome c reductase, cytochrome oxidase, aspartate aminotransferase and alanine aminotransferase. Patients showed an increase in lactate dehydrogenase, total NADH cytochrome c reductase and succinate dehydrogenase activities, a decrease in glycogen, ATP and CP concentrations. Telethermographic data showed patient muscle thermic emission quantitatively different from control group. The telethermographic test can be used as an additional diagnostic tool to determine and monitor the efficiency of a muscle undergoing metabolic failure.

Effects of hypoxia on enzyme activities in skeletal muscle of rats of different ages. An attempt at pharmacological treatment

The activities of enzymes related to energy metabolism in the gastrocnemius and soleus muscles in young-adult (4 months), mature (12 months) and senescent (24 months) rats were compared after 72 h of continuous exposure to normobaric hypoxia or normoxia after alpha-adrenergic antagonist nicergoline or saline solution had been given intraperitoneally for 30 consecutive days. The maximum rates (Vmax) of the following enzyme activities in the crude extract and/or the mitochondrial fraction of each muscle specimen were evaluated: (1) for the anaerobic glycolytic pathway: hexokinase, phosphofructokinase, pyruvate kinase and lactate dehydrogenase; (2) for the tricarboxylic acid cycle; citrate synthase and malate dehydrogenase; (3) for the electron transfer chain; cytochrome oxidase; and (4) for the NAD+/NADH redox state: total NADH cytochrome c reductase. The significant differences between the enzyme activities at different ages or under different experimental conditions in the two tissue preparations of the two muscles were determined by ANOVA. MCA and ETA were used to evaluate the net effects of the experimental conditions. Ageing did not seem to affect the soleus and gastrocnemius muscles in the same way. Changes were seen only in the glycolytic pathway enzymes in the crude extract from the gastrocnemius muscle. In the soleus muscle changes in enzyme activities as a function of ageing were also found in the mitochondrial fraction. We also found that hypoxia caused greater changes in 12-month-old rats than in those of other ages (especially in the enzyme activities of the gastrocnemius muscle). Finally out data show that only in certain cases was the pharmacological treatment able to modify the influence of hypoxic conditions on the levels of enzyme activities, regardless of the age of animals.

Biochemical evaluations in skeletal muscles of primates with MPTP Parkinson-like syndrome

The toxic effects of the neurotoxin MPTP (1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine) in primates can be exploited for investigating the physiopathology of Parkinson's disease which may also cause functional alterations of skeletal muscles, whose biochemical modifications have been studied very little. Some enzyme activities related to energy transduction in skeletal muscles were evaluated (gastrocnemius, soleus and biceps) from MPTP-treated monkeys. Systemically administered MPTP altered the enzyme activities related to: (i) the anaerobic glycolytic pathway (decrease in hexokinase and phosphofructokinase activities; increase in lactate dehydrogenase activity); (ii) the tricarboxylic acid cycle (decrease in malate dehydrogenase activity); (iii) the electron transfer chain (decrease in cytochrome oxidase activity related to complex IV). No alteration in mitochondrial Complex I was observed. Treatment with an ergot alkaloid derivative (dihydroergocryptine) modified some alterations in the muscle enzyme activities and reduced the rigidity and some autonomic dysfunction.

Imperforate hymen with bilateral hydronephrosis: an unusual emergency department diagnosis

Imperforate hymen is a rare diagnosis to make in the emergency department and important to treat immediately. Hydronephrosis is a known but rare complication of an imperforate hymen. We present the case of a premenstrual adolescent with an undiagnosed imperforate hymen complaining of increasing abdominal pain. The article discusses the history, physical examination, evaluation, differential diagnosis, ultrasound findings, complications, and prompt surgical treatment necessary.

Toxic shock syndrome following diagnostic peritoneal lavage

We report the case of a 15-year-old girl who developed high fever, syncope, abdominal pain, nausea and vomiting, myalgia, pharyngitis, and a desquamating rash eight days after a diagnostic peritoneal lavage. The diagnostic peritoneal lavage wound was erythematous and tender. Incision of the site yielded 10 mL of exudate that cultured Staphylococcus aureus. The patient was treated with a first-generation cephalosporin and recovered without sequelae. To our knowledge, this is the first reported case of toxic shock syndrome following diagnostic peritoneal lavage.