Observational Study With CICR-NAM as a Food for Special Medicinal Purposes in Post-COVID Syndrome (PCS)

In the COVit-2 study (DRKS00021214), daily intake of two tablets containing a total of 1,000 mg nicotinamide (500 mg conventional nicotinamide and 500 mg controlled-ileocolonic-release nicotinamide, CICR-NAM) in patients with acute COVID-19 was associated with a significantly faster improvement in physical performance after two weeks compared with placebo. Parallel effects on the gut metagenome suggested that specifically the ileocolonically released nicotinamide from CICR-NAM tablets could counteract COVID-19-associated disturbances in the metabolism of the essential amino acid tryptophan and in the gut microbiome. In the placebo group, gene expression related to the microbial tryptophan biosynthesis pathway as well as redox and salvage pathways of the central metabolic coenzyme nicotinamide adenine dinucleotide (NAD+) was significantly increased at week 2, whereas these deviations in the metagenome were not observed in patients receiving nicotinamide supplementation.

At the 6-month follow-up of COVit-2 participants, patients who benefited from nicotinamide administration (responders) developed post-COVID syndrome significantly less frequently. Because disturbances in tryptophan metabolism are well described in both COVID-19 and PCS, a low tryptophan level may serve as an easily measurable surrogate parameter for an increased nicotinamide requirement in these conditions.

There is currently no satisfactory treatment for patients with PCS. They experience significant distress and often have a permanent disability. Given the disturbances in tryptophan metabolism and the gut microbiome observed in PCS, supplementation with CICR-NAM may help restore physical performance. Therefore, a nutritional observational study offering 500 mg/day CICR-NAM as a food for special medicinal purposes for up to approximately 4 months will be conducted within the therapy groups of the PCS outpatient clinic at UKSH Campus Kiel for patients with documented tryptophan deficiency. A placebo-controlled clinical trial with CICR-NAM in PCS is planned, but it will not be available for recruitment in the near future. The present observational study is intended as an interim option until the clinical trial begins and is also expected to provide insights into the feasibility of such an intervention.

Inclusion criteria

• all sexes;
• minimum age 18 years; no upper age limit;
• post-COVID syndrome (PCS)
• serum tryptophan <55 µmol/L (UKSH reference range: 48-109 µmol/L);
• participation in the therapy groups of the PCS outpatient clinic at UKSH Campus Kiel.

Exclusion criteria

• Known allergies or intolerances to any component of CICR-NAM;
• inability to provide informed consent;
• pregnancy or breastfeeding;
• severe comorbid disease (especially renal insufficiency, uncontrolled autoimmune diseases, liver disease, or malignancy);
• long-term use of higher doses of medications that raise gastric pH (for example proton pump inhibitors, H2 receptor antagonists, or antacids), as an increase in pH toward approximately 7 may cause premature release of nicotinamide from CICR-NAM;
• use of supplements containing more than 20 mg nicotinamide, nicotinamide riboside, nicotinamide mononucleotide, nicotinic acid, or NAD+ per daily dose.