Clinical efficacy and safety of a novel intravenous immunoglobulin preparation in adult chronic ITP

Use of intravenous immunoglobulins (IVIGs) is a well-established therapy in patients with acute or chronic autoimmune thrombocytopenic purpura (ITP). The aim of the present open, prospective study was to investigate efficacy and safety of the novel IVIG preparation BT681 (Biotest Pharma GmbH, Dreieich, Germany) in adult patients with chronic ITP (cITP). In order to fulfil high standards of purity and viral safety, an additional HPLC step has been introduced and validated virus removal and inactivating procedures are included in the manufacturing process of BT681. A total of 24 patients with platelet counts between 3/nl and 27/nl received a total dose of 2 g/kg body weight BT681 in standard dosage regimens: 1.0 g/kg/day for 2 days in 15 patients and 0.4 g/kg/day for five consecutive days in nine patients. Platelet response (platelet count > or =50/nl) and regression of haemorrhages were documented during the 28 days study period and safety parameters including adverse events, laboratory investigations and vital signs were regularly monitored. The overall response rate was 91.7%, that is 22/24 patients responded to BT681 treatment. The median time to platelet response was 3.0 days, the duration of response 25.5 days; the median max. platelet count 222/nl and the time to max. platelet count 7.5 days. During the entire observation period, platelet counts below baseline were only observed in five responders; in half of the patients, platelet counts were even above 50/nl at the end of follow-up. Corresponding to the good platelet response, the clinical symptoms improved markedly in the majority of patients within the first week after start of BT681 infusions with 88.9% overall regression of haemorrhages in comparison with baseline. The evaluation of platelet parameters showed a slight tendency in favour of the 5 days group, evaluation of haemorrhage severity slight advantages for the 2 days group. The adverse event data indicate that the therapy with BT681 was safe and well tolerated in both treatment groups even if minor effects were more frequent in patients treated with the 2 days regimen. The large majority of adverse events were known intolerabilities during the treatment phase described as mild and transient. The results demonstrate that the new immunoglobulin preparation BT681 is effective and safe in the treatment of adult patients with cITP.

Pharmacokinetics of viral antibodies after administration of intravenous immunoglobulin in patients with chronic lymphocytic leukaemia or multiple myeloma

OBJECTIVE

Intravenous immunoglobulin (IVIG) preparations are derived from human pooled plasma and should fulfil high standards of purity and viral safety. Introduction of additional purification steps, however, may result in modulation of the biological properties of immunoglobulins. Since cleavage of the Fab-fragment leads to a significant decrease in half-life, the latter provides information about the integrity of the immunoglobulin G (IgG) molecules. Therefore, a pharmacokinetic study of a novel preparation is required to determine safety and disposition in the target population.

METHODS

Twenty-seven patients with chronic lymphocytic leukaemia (CLL) and 12 with multiple myeloma received intravenous infusions of IVIG containing antibodies against hepatitis B virus (anti-HBs; n= 15; 8960 IU), cytomegalovirus (anti-CMV; n = 9; 14,250 U) or varizella-zoster-virus (anti-VZV; n = 15; 6000 IU), respectively. Serum concentrations of viral antibodies were determined for 71 days during and after infusion.

RESULTS

Maximum serum concentrations of anti-HBs, anti-CMV and anti-VZV were observed at about 4 h (median) after start of the infusion. Total body clearances came to 0.14 +/- 0.08 ml/min (anti-HBs), 0.10 +/- 0.02 ml/ min (anti-CMV) and 0.14 +/- 0.07 ml/min (anti-VZV). The terminal elimination half-lives were determined to be 25.34 +/- 8.34 days (anti-HBs), 24.66 7.28 days (anti-CMV) and 31.79 +/- 12.47 days (anti-VZV). Clinical chemistry parameters including C3- and C4-complement serum concentrations revealed no pathological changes, seroconversion for hepatitis B and C and HIV did not occur.

CONCLUSIONS

The pharmacokinetic parameters of the IgG antibodies calculated after administration of the novel IVIG preparations to patients with CLL and multiple myeloma are in close agreement with data obtained from healthy volunteers and with values of native IgG, suggesting that the production process did not impair clinically relevant characteristics of the viral antibodies.

Acute and chronic haemodynamic and natriuretic effects of atriopeptin II in conscious rats

The haemodynamic and natriuretic effects of an atrial natriuretic peptide were studied in conscious rats during acute and chronic administration of the peptide. Infusion of atriopeptin II (0.3 microgram/kg per min intravenously) for 60 min produced a fall in blood pressure and a rise in heart rate, accompanied by a significant decrease in renal and mesenteric blood flow. Despite the renal vasoconstriction, urinary sodium excretion increased markedly. These findings suggest that the hypotensive effect of atriopeptin II in conscious rats is not mediated by systemic vasodilatation, and that renal vasodilatation is not a prerequisite for the natriuretic action of this peptide. During infusion of atriopeptin II (24 micrograms/day) for 2 days, a small but persistent hypotensive effect was observed, which was accompanied by transient tachycardia. However, infusion of the same, or a higher (120 micrograms/day), dose of atriopeptin II for 4 days failed to produce any natriuretic effects. These results suggest that atrial natriuretic peptides are more important in acute than in chronic regulation of sodium excretion.

Is the natriuretic effect of atrial natriuretic factor in conscious rats mediated by renal vasodilatation?

Atrial natriuretic factors (ANF) have both vasorelaxant and natriuretic properties. It has been suggested that their effects on sodium excretion depend on renal vasodilatation. We studied the haemodynamic (ultrasound Doppler flow probes) effects of synthetic atriopeptin II at natriuretic doses in conscious rats. Intravenous injections of atriopeptin II induced a marked, dose-dependent increase in sodium excretion. This was accompanied by a slight reduction in blood pressure (BP) and a transient decrease in renal, mesenteric and aortic blood flow. In contrast, a selective renal vasodilator, CGP 22,979, induced a moderate increase in sodium excretion concomitantly with a rise in renal blood flow. Blood pressure and the other regional flows remained unchanged. These findings suggest that the natriuretic effect of CGP 22,979 is closely related to an increased renal blood flow. Conversely, the natriuresis induced by atriopeptin II is not accompanied by selective renal vasodilatation and appears to be due either to a tubular action or to changes in intrarenal haemodynamics.

Reduced activity of locus coeruleus neurons in hypertensive rats

The effect of blood pressure on the neuronal activity of the locus coeruleus (LC) was investigated by means of electrophysiological techniques in rats anaesthetized with chloral hydrate. The mean neuronal discharge rate of noradrenergic neurons of the LC was reduced by 19% in spontaneously hypertensive rats (SHR) and by 25% in deoxycorticosterone acetate (DOCA)-salt hypertensive rats compared with their corresponding controls. The cellular activity of 27 out of 40 neurons was reversibly suppressed by acute, peripherally induced blood pressure increases in normotensive rats. Five neurons were reversibly activated and eight neurons were not affected. Conversely, acute decreases in blood pressure stimulated the neuronal activity of the LC in 10 out of 16 neurons. These findings support the hypothesis of the LC having a role in both short and long term regulation of blood pressure.

Reduced activity of locus coeruleus neurons in hypertensive rats

The influence of blood pressure on locus coeruleus (LC) neuronal activity was investigated in chloral hydrate anesthetized rats. Mean spontaneous firing rate of LC neurons was reduced by 25% in deoxycorticosterone acetate (DOCA-salt) treated Sprague-Dawley rats and by 19% in spontaneously hypertensive rats (SHR) as compared to their corresponding control animals. In acute experiments performed on normotensive rats, peripherally induced blood pressure changes elicited reciprocal changes in cell firing of the majority of LC neurons. The findings suggest that LC may have a role in long-term regulation of blood pressure.

CGP 22979A, a renal vasodilator with natriuretic properties

Renal vasodilation might be an interesting new antihypertensive principle. In the present study, the prodrug approach was adopted to synthesize a preferential renal vasodilator. A hydralazine-like compound, CGP 18137A (2-hydrazino-5-n-butyl-pyridine), was substituted with an N-acetyl-gamma-glutamyl residue. The resulting derivative, CGP 22979A [N-acetyl-L-glutamic acid-N[N2-(5-n-butyl-2-pyridyl)hydrazide]], was inactive in the isolated perfused mesenteric artery, whereas the parent compound induced a dose-dependent inhibition of vasoconstrictor stimuli. When administered i.v. to anesthetized rats in doses between 1.0 and 10.0 mg/kg, CGP 22979A increased renal blood flow significantly, by up to 31% without affecting blood pressure. A dose of 4.0 mg/kg lowered renal vascular resistance by 25% but did not alter total systemic, mesenteric and iliac vascular resistance. A dose of 10.0 mg/kg increased glomerular filtration rate by up to 42%. In conscious rats, the same dose increased sodium excretion by 200%. Because CGP 22979A induces renal vasodilation in rats and has a preferential action on the afferent arterioles, it might be a useful tool for studying the antihypertensive potential of renal vasodilation.

Glomerular Albumin Leakage and Morphology after Neutralization of Polyanions. I

In order to decide whether foot process abnormalities in nephrotic states are the cause or the consequence of proteinuria, the polycation protamine has been applied to isolated perfused rat kidneys and functional parameters and morphology have been compared. With 110 μg/ml protamine the albumin clearance ratio increased from 2.0 + 0.7 × 10^-3 in controls to 14.8 + 6.9 × 10^-3 10-20 min after application and even to 98.0 + 30.8 × 10^-3 after 50-80 min. Micropuncture samples collected from early proximal tubules with pressure control were used to calculate the sieving coefficient which correlated with albumin clearance ratios (controls: 1.8 +1.0 × 10^-3; after 10-20min: 11.8 ± 6.4 × 10^-3; after 50-80 min: 52.0 + 8.5 × 10^-3). Glomerular filtration rate decreased in the early beginning from 1.1 ± 0.2 ml x min^-1 ×g^-1 kidney to 0.7+ 0.2 ml × min^-1 ×g^-1 kidney, but remained constant throughout the whole experiment. Despite the markedly increased albuminuria there were no changes in glomerular foot process morphology with the protamine dose used.