Handley and Stewart demonstrated its effectiveness in the treatment of patients who failed to respond to other therapies; it was noted to be more effective in people with idiopathic generalized epilepsy than in people whose epilepsy had a known cause. Dr. Whitty noted in 1953 that it benefitted patients with psychomotor epilepsy, who were often treatment-resistant. Toxic effects were reported to be mild. That same year, it was approved in France. Primidone was introduced in 1954 under the brandname Mysoline by Wyeth in the United States. Association with megaloblastic anemia
In 1954, Chalmers and Boheimer reported that the drug was associated with megaloblastic anemia. Between 1954 and 1957, twenty-one cases of megaloblastic anemia associated with primidone and/or phenytoin were reported. In most of these cases the anemia was due to vitamin deficiencies: usually folic acid deficiency; in one case Vitamin B12 deficiency and in one case Vitamin C deficiency. Some cases were associated with deficient diets: one patient ate mostly bread and butter, another ate bread, buns, and hard candy, and another could rarely be persuaded to eat in the hospital.The idea that folic acid deficiency could cause megaloblastic anemia was not new. What was new was the idea that drugs could cause this in well-nourished people with no intestinal abnormalities. In many cases, it was not clear which drug had caused it. It was speculated that this might be related to the structural similarity between folic acid, phenytoin, phenobarbital, and primidone.
Methazolamide (trade name Neptazane) is a potent carbonic anhydrase inhibitor. It is indicated in the treatment of increased intraocular pressure (IOP) in chronic open-angle glaucoma and secondary glaucoma. Also it is used preoperatively in acute angle-closure (narrow-angle) glaucoma where lowering the IOP is desired before surgery. This drug has displayed teratogenic effects in rats. Compared to another drug in the same class, Acetazolamide, Methazolamide requires a lower dose when administered to patients. References
Iyer G, Bellantone R, Taft D (1999). "In vitro characterization of the erythrocyte distribution of methazolamide: a model of erythrocyte transport and binding kinetics". J Pharmacokinet Biopharm. 27 (1): 45–66. doi:10.1023/A:1020630712388. PMID 10533697. S2CID 24294348. RxList. "Neptazane". Archived from the original on August 12, 2006. Retrieved August 20, 2006. Shirato S, Kagaya F, Suzuki Y, Joukou S (1997). "Stevens–Johnson syndrome induced by methazolamide treatment". Arch Ophthalmol. 115 (4): 550–3. doi:10.1001/archopht.1997.01100150552021. PMID 9109770. Skorobohach B, Ward D, Hendrix D (2003). "Effects of oral administration of methazolamide on intraocular pressure and aqueous humor flow rate in clinically normal dogs". Am J Vet Res. 64 (2): 183–7. doi:10.2460/ajvr.2003.64.183. PMID 12602587.