On the reactivity of ascomycin at the binding domain. Part 1: Liberation of the tricarbonyl portion of ascomycin

Combating Alcohol Adduct Impurity in Immunosuppressant Drug Product Manufacturing: A Scientific Investigation for Enhanced Process Control

OBJECTIVE

This research aims to elucidate critical impurities in process validation batches of tacrolimus injection formulations, focusing on identification and characterization of previously unreported impurity at RRT 0.42, identified as the tacrolimus alcohol adduct. The potential root causes for the formation of new impurity was determined using structured risk assessment by cause and effect fishbone diagram. The primary objective was to propose mitigation plan and demonstrate the control of impurities with 6 month accelerated stability results in development batches.

METHODS

The investigation utilizes method validation and characterization studies to affirm the accuracy of quantifying the tacrolimus alcohol adduct. The research methodology employed different characterization techniques like rotational rheometer, ICP‒MS, MALDI-MS, 1H NMR, 13C NMR, and DEPT-135 NMR for structural elucidation. Additionally, the exact mass of the impurity is validated using electrospray ionization mass spectra.

RESULTS

Results indicate successful identification and characterization of the tacrolimus alcohol adduct. The study further explores the transformation of Tacrolimus monohydrate under various conditions, unveiling the formation of Tacrolimus hydroxy acid and proposing the existence of a novel degradation product, the Tacrolimus alcohol adduct. Six-month data from development lots utilizing Manufacturing Process II demonstrate significantly lower levels of alcohol adducts.

CONCLUSIONS

Manufacturing Process II, selectively locates Tacrolimus within the micellar core of HCO-60, this prevent direct contact of ethanol with Tacrolimus which minimizes impurity alcohol adduct formation. This research contributes to the understanding of tacrolimus formulations, offering ways to safeguard product integrity and stability during manufacturing and storage.

Discovery of Topical Calcineurin Inhibitors and Pharmacological Profile of Pimecrolimus

Using a newly developed model of allergic contact dermatitis in pigs, calcineurin inhibitors of the tacrolimus and ascomycin type were shown to have a highly anti-inflammatory action after topical application. These findings provided the first pharmacological evidence of the efficacy of this novel class of topical agents in the treatment of inflammatory skin diseases, and, thus, their potential to become the first alternative to corticosteroids in more than 40 years. As a result of a large research program into ascomycins, pimecrolimus (Elidel(R), SDZ ASM 981) was selected for development due to its favorable pharmacology and safety profile, alongside tacrolimus (Protopic(R), FK 506). In vitro, pimecrolimus inhibits the transcription and release of pro-inflammatory cytokines in T cells. Similar to the corticosteroids, betamethasone-17-valerate and dexamethasone, pimecrolimus is effective at nanomolar concentrations. Targeting mainly T cells, pimecrolimus has, however, a more specific mode of action. Moreover, in contrast to corticosteroids, pimecrolimus has no effect on Langerhans' cells, the professional antigen- presenting dendritic cells of the skin that are crucial for local immunosurveillance. When applied topically, pimecrolimus exerts a high and selective anti-inflammatory activity in the skin, shows minimal percutaneous absorption, and has a low potential to affect systemic immunoreactions. Pimecrolimus cream 1% has proven to be well tolerated, safe, and highly effective in clinical studies in patients with atopic dermatitis.