While usually associated with Crohns disease, ileitis (inflammation of the ileum) also occurs in UC. About 17% of individuals with UC have ileitis. Ileitis more commonly occurs in the setting of pancolitis (occurring in 20% of cases of pancolitis), and tends to correlate with the activity of colitis. This so-called "backwash ileitis" can occur in 10–20% of people with pancolitis and is believed to be of little clinical significance. Severity of disease
In addition to the extent of involvement, UC is also characterized by severity of disease. Severity of disease is defined by symptoms, objective markers of inflammation (endoscopic findings, blood tests), disease course, and the impact of the disease on day-to-day life. Most patients are categorized through endoscopy and fecal calprotectin levels. Indicators of low risk for future complications in mild and moderate UC include the following parameters: exhibiting less than 6 stools daily and lack of fever/weight loss. Other indicators include lack of extraintestinal symptoms, none to little elevation in CRP, ESR, and calprotectin, and later age of diagnosis (over 40 years). Mild disease correlates with fewer than four stools daily; in addition, mild urgency and rectal bleeding may occur intermittently. Mild disease lacks systemic signs of toxicity (eg. fever, chills, weight changes) and exhibits normal levels of serum inflammatory markers (erythrocyte sedimentation rate and C-reactive protein).Moderate to severe disease correlates with more than six stools daily, frequent bloody stools and urgency. Moderate abdominal pain, low-grade fever, 38 to 39 °C (100 to 102 °F), and anemia may develop (75% of normal).
The authors did not observe significant safety risks using the low quinidine dose, but urged caution and also pointed out that quinidine interacts with a large number of other medications in dangerous or unpredictable ways. Interestingly, a meta analysis was published referencing only that one study.Although intravenous quinidine is sometimes used to treat Plasmodium falciparum malaria, the future availability of this agent is uncertain. Side effects
Quinidine is also an inhibitor of the cytochrome P450 enzyme 2D6, and can lead to increased blood levels of lidocaine, beta blockers, opioids, and some antidepressants. Quinidine also inhibits the transport protein P-glycoprotein and so can cause some peripherally acting drugs such as loperamide to have central nervous system side effects, such as respiratory depression, if the two drugs are coadministered.Quinidine can cause thrombocytopenia, granulomatous hepatitis, myasthenia gravis, and torsades de pointes (dangerous heart rhythm), so is not used much today. Torsades can occur after the first dose. Quinidine-induced thrombocytopenia (low platelet count) is mediated by the immune system, and may lead to thrombocytic purpura. Quinidine intoxication can lead to a collection of symptoms collectively known as cinchonism, with tinnitus (ringing in the ears) being among the most characteristic and common symptoms of this toxicity syndrome. Pharmacology
Pharmacodynamics
Quinidine acts as a blocker of voltage-gated sodium channels. Inhibition of the Nav1.5 channel is specifically involved in its antiarrhythmic effects as a class I antiarrhythmic agent. Quinidine also blocks certain voltage-gated potassium channels (e.g., Kv1.4, Kv4.2, hERG, among others), acts as an antimuscarinic and alpha-1 blocker, and is an antimalarial.