A Review of Factor VIII and Factor IX Assay Methods for Monitoring Extended Half-Life Products in Hemophilia A and B

Clinical trials have used a variety of coagulation factor assay methods to assess treatment with recombinant Factor VIII (rFVIII) and recombinant Factor IX (rFIX) extended half-life (EHL) products. However, diagnostic laboratories may use different reagent combinations for routine use or for field trials of EHL products. The focus of this review is on the choice of one-stage clotting and chromogenic Factor VIII and Factor IX methods and the influence that assay principle and components may have on results, including the effects of different activated partial thromboplastin time reagents and factor-deficient plasma. Our aim is to tabulate the findings for each method and reagent group to give laboratories practical guidance as to how the reagent combinations used in their local laboratory compare to others, for the various EHLs available.

Potency of botulinum toxin drugs: test systems and labelling

Cell-based assays are a novel method to determine potency of botulinum toxin drugs. Manufacturers are working on their acquisition, development and implementation to reduce animal consumption during the manufacturing process. Potency labelling of botulinum toxin drugs differes principally between Ipsen and the other manufacturers. Reference to a uniform international standard would avoid this potentially dangerous situation. However, this has not been demanded by the registration authorities and has not been persued by the manufacturers for decades.

Comparing lanbotulinumtoxinA (Hengli®) with onabotulinumtoxinA (Botox®) and incobotulinumtoxinA (Xeomin®) in the mouse hemidiaphragm assay

LanbotulinumtoxinA (LAN) is manufactured and registered in China since 1994. Despite its widespread use in China and its increasing use in other Asian countries and in South America, it is not yet well known elsewhere. We wanted to compare its potency labelling using the mouse diaphragm assay (MDA), an isolated muscle model for botulinum toxin (BT) potency measurements, which is superior to clinical tests and which was recently refined as an alternative batch release assay for BT manufacturing. We also wanted to estimate LAN manufacturing quality by testing its inter-batch potency consistency. Potencies of 20, 60 and 100 MU of LAN, onabotulinumtoxinA (ONA) and incobotulinumtoxinA (INCO) were measured by the inversely related paresis time (PT) in the MDA. The PT (M ± SD) of all doses of LAN, ONA and INCO was 90.4 ± 27.0 min, 114.9 ± 46.5 min and 94.3 ± 29.9 min, respectively. Statistical analysis demonstrated indistinguishable potency labelling of LAN and INCO, but revealed a slightly lower potency of ONA compared to LAN and INCO. PT of LAN batch 1 and LAN batch 2 was 86.9 ± 21.2 min and 94.0 ± 32.8 min, respectively (no statistically significant difference), suggesting an adequate LAN manufacturing consistency. The MDA is an appropriate instrument for potency testing of BT drugs, including new ones currently under development. Our results allow comparing therapeutic effects, adverse effects and economics of LAN, ONA and INCO. They also suggest adequate manufacturing consistency of LAN.

Clinical Pharmacology of Botulinum Toxin Drugs

Botulinum toxin (BT) has changed from a deadly poison to a novel therapeutic principle for a large number of disorders in many medical areas.BT drugs are special in many ways: they are biologicals, their active ingredient BT is not patentable, their spectrum of clinical applications is extremely broad, their dose range is enormous, their mode of action is local and their life cycles are special.This review covers BT's therapeutic mode of action, time course of action, target tissues, pharmacological profile, adverse effects, interactions, potency labelling and antigenicity as well as BT's therapeutic preparations.

Comparing incobotulinumtoxinA (Xeomin®) and onabotulinumtoxinA (Botox®): identical potency labelling in the hemidiaphragm assay

Botulinum toxin (BT) is provided by several manufacturers producing a number of different drugs. Their potency is given in internationally standardised mouse units (MU). Clinical practise, however, reveals that the potency labelling of different BT drugs may not be identical. We wanted to use the mouse diaphragm assay (MDA) to compare the two BT drugs onabotulinumtoxinA (ONA) and incobotulinumtoxinA (INCO). For this, we measured the paresis time (PT) of different ONA or INCO doses. All BT came from several different and unexpired drug batches. PT for 20MU were 169.7 ± 28.9 min (ONA) and 132.3 ± 1.5 min (INCO) (p = 0.089), for 60MU 105.3 ± 10.1 min and 84.7 ± 4.2 min (p = 0.031), for 100MU 69.7 ± 1.5 min and 66.0 ± 7.0 min (p = 0.462) and for 140MU 74.7 ± 0.6 min and 62.3 ± 2.1 min (p = 0.100), respectively. The overall PT were 104.8 ± 12.5 and 86.3 ± 8.5 min (p = 0.178). Results presented here do not reveal differences in potency labelling between ONA and INCO, even when the full range of therapeutic doses are examined, although there was a trend towards stronger INCO effects. Data confirm previous reports on identical potency labelling of ONA and INCO. The MDA seems to be an appropriate instrument to test the potency labelling of other BT drugs as well, including new BT drugs currently under development.