Methazolamide

High Altitude Renal Syndrome (HARS) is a clinical syndrome characterized by polycythemia, hyperuricemia, hypertension, and albuminuria at high altitudes. This review emphasizes hypoxia-induced High Altitude Polycythemia (HAPC) as its core driver. In 2014, the 6th Qinghai International Conference on Mountain Medicine and High Altitude Physiology established international diagnostic criteria for HAPC (hemoglobin ≥210g/L in males, ≥190g/L in females). HAPC triggers systemic hypoxia, leading to hyperuricemia via uric acid overproduction and reduced renal excretion, hypertension from hemodynamic changes, and glomerular injury through erythrocytosis. Pathological mechanisms involve HIF-2α-mediated glomerular hypertrophy and podocyte damage. Treatment strategies target HAPC and downstream effects. Carbonic anhydrase inhibitors (e.g., acetazolamide) reduce hematocrit and improve oxygen saturation, but newer agents like methazolamide and dichlorphenamide offer equivalent efficacy with fewer side effects (e.g., reduced central nervous system toxicity). For severe cases, descending to lower altitudes remains the gold standard. Additional interventions include calcium channel blockers (nifedipine), urate-lowering drugs, and experimental therapies such as HIF-2α inhibitors (PT2385) and endothelin receptor antagonists (matitan). This analysis underscores HAPC as the primary etiology of HARS, advocating revised diagnostic criteria and treatment prioritization.

Reactive oxygen species (ROS) are generated as byproducts of oxygen metabolism and play multiple roles in biol. systems.In addition, these species can be generated in the eye as a result of the photosensitizing action of pigments that are naturally present in this organ, such as riboflavin.An imbalance between the production of ROS and the response of the antioxidant defense system results in oxidative stress.In humans, the oxidative stress can lead to the initiation or development of many ocular diseases and injuries (glaucoma, cataracts, macular degeneration).In this highly oxidative cellular environment, topically administered drugs for the treatment of various pathologies may be susceptible to be attacked by ROS and consequently degraded, losing their clin. efficacy or generating toxic products.In this contribution, the kinetics of ROS-mediated degradation of the antiglaucoma drugs, acetazolamide and methazolamide, was investigated.In order to analyze the effects that these drugs and their derivatives produce on the viability of normal human cells, this parameter was evaluated in the MRC-5 line.Results showed that acetazolamide and methazolamide interact with the electronic triplet state of riboflavin and with different photo-generated ROS from this state.Both drugs were chem. degraded by singlet oxygen, although methazolamide was more reactive than acetazolamide.The experiments demonstrated that neither the drugs nor their ROS-mediated oxidation products exhibited cytotoxicity in the MRC-5 cell line.On the other hand, under direct UV irradiation, AZ and MZ generated O₂(¹Δ_g) with considerable efficiency compared to other ophthalmic drugs and would be considered good sensitizers.