Human health and medicine

RIDE trial

RIDE (NCT00473382), with sister trial RISE, was a phase 3 sham-controlled trial of monthly intravitreal ranibizumab (0.3 mg, 0.5 mg) for diabetic macular edema; 382 patients, ≥15-letter ETDRS gains at 24 months, basis of 2012 US approval.

Ridinilazole

Ridinilazole (formerly SMT19969) is a non-absorbable, narrow-spectrum bis-benzimidazole antibiotic for Clostridioides difficile infection that binds C. difficile DNA in the minor groove; phase 3 trials showed lower recurrence than vancomycin but missed superiority, and Summit sold it to Biossil in 2026.

Rieger anomaly

Rieger anomaly is a congenital eye defect featuring iris stroma thinning, hole formation, corectopia, and features of Axenfeld's anomaly, with glaucoma in about half of patients.

Rifalazil

Rifalazil (KRM-1648, ABI-1648), a benzoxazinorifamycin antibiotic from Kaneka, inhibits bacterial RNA polymerase with a ~60 h half-life; phase II trials for tuberculosis and chlamydia ended after toxicity, development terminated 2013.

Rifampicin

Rifampicin (rifampin), a semisynthetic rifamycin antibiotic from Amycolatopsis rifamycinica developed by Lepetit in 1965, inhibits bacterial DNA-dependent RNA polymerase and anchors 6-month tuberculosis therapy; resistance maps to rpoB and it strongly induces CYP3A4.

Rifamycin

Rifamycin is a class of antibiotics from the soil bacterium Amycolatopsis mediterranei, first isolated in 1957, that kill bacteria by inhibiting RNA polymerase and include rifampicin, the backbone of tuberculosis therapy.

Rifapentine

Rifapentine (Priftin) is a cyclopentyl rifamycin antibiotic for tuberculosis, FDA approved 1998; with isoniazid it forms the 3HP and 1HP preventive regimens; resistance via rpoB mutations.

Rifaquizinone

Rifaquizinone (TNP-2092, CBR-2092) is a rifamycin-quinolizinone hybrid antibiotic by TenNor Therapeutics that inhibits RNA polymerase, DNA gyrase, and topoisomerase IV, developed for prosthetic joint infections and ABSSSI.

Rifasutenizol

Rifasutenizol (TNP-2198), TenNor Therapeutics' rifamycin-nitroimidazole conjugate antibiotic, targets H. pylori via dual RNA polymerase inhibition and nitroreductase-mediated DNA damage; Phase 3 showed ~92% eradication, NDA filed August 2025.

Rifaximin

Rifaximin (Xifaxan), a minimally absorbed rifamycin antibiotic binding bacterial RpoB RNA polymerase; treats travelers' diarrhea, IBS-D, and hepatic encephalopathy; <0.4% absorbed, 97% recovered unchanged in stool.

Riferminogene pecaplasmid

Riferminogene pecaplasmid (NV1FGF, XRP0038) is a Sanofi-aventis pCOR plasmid gene therapy expressing FGF-1 for critical limb ischemia; its phase III TAMARIS trial showed no benefit over placebo.

Rift Valley fever

Rift Valley fever (RVF), a mosquito-borne Phlebovirus zoonosis first identified in Kenya in 1931, infects livestock and humans via contact with animal blood or Aedes/Culex mosquito bites; no human-to-human spread documented.

Right aortic arch

Right-sided aortic arch (RAA), a congenital variant where the aortic arch courses right of the trachea, occurring in about 0.1% of people; main types are mirror-image branching and aberrant left subclavian artery, the latter forming a compressive vascular ring.

Right axis deviation

Right axis deviation (RAD): an ECG finding where the frontal-plane QRS axis exceeds +90°, caused by right ventricular hypertrophy, pulmonary embolism, COPD, or left posterior fascicular block, and associated with higher long-term mortality.

Right bundle branch block

Right bundle branch block (RBBB) is a disorder of the heart's electrical conduction in which the right ventricle is activated late, producing a widened QRS complex on the electrocardiogram.

Right colectomy

A right colectomy, or right hemicolectomy, is surgery that removes the right colon with terminal ileum and lymph nodes, most often to treat cancer of the cecum or ascending colon.

Right coronary artery

Right coronary artery (RCA): artery from the right sinus of Valsalva supplying the right heart, SA/AV nodes, and inferior wall; dominant in about 70–90% of people; most common anomaly is origin from the left coronary sinus.

Right Heart Bypass

Right heart bypass: surgical principle routing systemic venous blood directly to the pulmonary arteries without a right ventricle, underlying the Glenn shunt (1958) and Fontan procedure (1971) for single-ventricle congenital heart disease.

Right heart strain

Right heart strain: right ventricular stress from overload, chiefly pulmonary embolism and pulmonary hypertension. Recognized by ECG signs (S1Q3T3, RBBB), RV dilation, septal flattening, TAPSE <16 mm, and RV strain imaging with prognostic cutoffs.

Right outflow tract ventricular tachycardia

Right outflow tract ventricular tachycardia (RVOT-VT), also called idiopathic RVOT VT, is a benign triggered-activity VT from the right ventricular outflow tract in structurally normal hearts, showing LBBB inferior-axis ECG, treated with beta-blockers, calcium channel blockers, or curative catheter ablation.

Right ventricular failure

Right ventricular failure is the syndrome of systemic venous congestion, with or without low cardiac output, caused by right ventricular dysfunction, most often from left heart failure raising pulmonary pressures.

Right ventricular hypertrophy

Right ventricular hypertrophy (RVH), thickening of the right ventricle wall from chronic pressure overload, seen in pulmonary hypertension, cor pulmonale, pulmonary stenosis, tetralogy of Fallot; diagnosed by echo, ECG, cardiac MRI.

Right ventricular myocardial infarction

Right ventricular myocardial infarction is death of heart muscle in the right ventricle, usually from proximal right coronary artery occlusion, causing shock with distended neck veins and clear lungs.

Right ventricular outflow tract reconstruction

Right ventricular outflow tract reconstruction is congenital heart surgery that rebuilds the passage from the right ventricle to the pulmonary artery, central to repairing tetralogy of Fallot.

Right-to-left shunt

Right-to-left shunt: abnormal flow of deoxygenated blood into the systemic circulation, causing cyanosis. Causes include Eisenmenger shunt reversal, complex congenital heart disease, PFO, and pulmonary AVMs; diagnosed by bubble echocardiography.

Righting Reflex (medicine)

The righting reflex is the inborn impulse to return the body to its normal orientation in space after displacement; its loss is a standard measure of unconsciousness in rodent research.

Rigid bronchoscopy

Rigid bronchoscopy inserts a hollow metal tube through the mouth into the trachea and central airways, usually under general anesthesia, to remove foreign bodies and treat airway lesions.

Rigid fixation

Rigid fixation is a surgical fracture technique providing absolute stability through compression with lag screws and plates, allowing direct bone healing without callus and early mobilization of the limb.

Rigid spine syndrome

Rigid spine syndrome, also called rigid spine congenital muscular dystrophy, is a congenital muscular dystrophy described by Victor Dubowitz in 1973, marked by spinal contractures, scoliosis, and progressive respiratory failure.