Asthma/ Allergies

Asthma and allergies are related. Asthma is traditionally treated with albuterol, methyl-xanthines, and steroids, while allergies are traditionally treated with antihistamines, and in severe cases, steroids or epinephrine.

Considering these compounds all as purine-similar, we see albuterol as a guanine-analogue, while 

In depressive patients with comorbid asthma, bupropion (albuterol similar) responders had co-occuring improvement in asthma PID 17645195. IMG

Phosphorylated vitamin B6 is hypothesized here to inhibit PRPP synthase, reducing co-reactant for aPRT, hgPRT, and xPRT. Adding a methylated xanthine theophyline (caffeine activates PNP a little and hgPRT a lot PMID 6149265) decreases phosphorylated pyridoxine, which is already low in asthmatics PMID 3384587, 8430923. Pyridoxine supplementation is low/no risk and decreased bronchodialator use and steroid dose in steroid dependent asthma: DBRCT PMID 1096686, but did not independently modify other PFTs DBRCT PMID 8430923. The earlier beneficial study was not included in a recent review due to age PMID 28143878.

All of these ideas point to asthma as a guanine deficit, but we already have a guanine deficit symptom-set in dystonia/Parkinsonism. Notably, the clinical association has been made prior to the guanine rationale: those with asthma and allergies are much more likely to suffer Parkinsonism PMID 26310430, 37544850, 37240888. Connection between the chemical structures of treatments (istradefyline and caffeine in PD and theophyline in asthma) suggests shared purinergic mechanism. Inadequacy of the xanthines suggests that guanase inhibition only goes so far to correct the underlying issue.