Table 5.
Difference between immunoglobulins (ScIg, IVIg) and typical drugs
| Feature | Drug/medicine | Immunoglobulin |
|---|---|---|
| Source | Chemical (for example catalytic, enzymatic) reaction “IN VITRO” | Plasma obtained from blood donorsa “IN VIVO” |
| Chemical composition, dose | Known (standardization following pharmacopeia) Dose [g] describe active compound content |
Not precisely defined Protein (in reality proteins complex) Dose [g] describe total protein content |
| Clinical pharmacology | ||
| Mechanism of action | Defined (by strict receptors) | Multifactorial (depends on antigenic specificity) |
| Elimination and half-life (T½) | Renal intestinal etc. after easy diffusion from tissue compartment Strictly defined T½ |
Not known Serum T½ does not reflect immunoglobulin elimination, but FcR opsonizationb |
| Unpredictable adrs | ||
| Immunogenicity | Usually low (in general haptenic formula) | Pathological anti—IgAc |
| Immunoreactivity (immune reaction to pharmaceutical product) | Rare, but ever probable (e.g. benzylpenicillin allergy) | Physiological tolerance or antiidiotypic immune responsed |
Immunoglobulins are a pharmaceutical product with unique technology, contrary to bio-synthetic drugs
aImmunoglobulin preparation is plasma fractionation: plasma is obtained in accordance with WHO guidelines from at least 1000 donors
bAfter immunoglobulin distribution to tissue compartment FcR opsonization occurs (see Figs. 2a, 3). It blocks inverse diffusion to serum
cIn clinical practice immunoglobulins are used as replacement therapy in patients with primary and secondary immunodeficiencies. Lack of active immune response after antigenic stimulation (e.g. vaccination) in such patients is one crucial mechanism of low immunogenicity. Contrary to CVID, patients with selective IgA deficiency may produce IgG that reacts with IgA in immunoglobulins (product characteristic of many immunoglobulins as well as Subcuvia® does not contain essential contraindication—selective IgA deficiency)
dWhen immunoglobulin is used in immunomodulatory therapy (autoimmune disease) the immune response to immunoglobulins and hyperreactivity may be observed. For example Rheumatoid factor from patients with autoimmune disease and IgG from pharmaceutical product