Development
During embryogenesis the ear develops as three distinct structures: the inner ear, the middle ear and the outer ear. Each structure originates from a different germ layer: the ectoderm, endoderm and mesenchyme. Inner ear
After implantation, around the second to third week the developing embryo consists of three layers: endoderm, mesoderm and ectoderm. The first part of the ear to develop is the inner ear, which begins to form from the ectoderm around the 22nd day of the embryos development. Specifically, the inner ear derives from two thickenings called otic placodes on either side of the head. Each otic placode recedes below the ectoderm, forms an otic pit and then an otic vesicle. This entire mass will eventually become surrounded by mesenchyme to form the bony labyrinth.Around the 33rd day of development, the vesicles begin to differentiate. Closer to the back of the embryo, they form what will become the utricle and semicircular canals. Closer to the front of the embryo, the vesicles differentiate into a rudimentary saccule, which will eventually become the saccule and cochlea. Part of the saccule will eventually give rise and connect to the cochlear duct. This duct appears approximately during the sixth week and connects to the saccule through the ductus reuniens.As the cochlear ducts mesenchyme begins to differentiate, three cavities are formed: the scala vestibuli, the scala tympani and the scala media. Both the scala vestibuli and the scala tympani contain an extracellular fluid called perilymph. The scala media contains endolymph.
Trandolapril is an ACE inhibitor used to treat high blood pressure. It may also be used to treat other conditions. It is similar in structure to another ACE Inhibitor, Ramipril but has a cyclohexane group. It also is a pro-drug and must get metabolized. It has an extended half-life and therefore has a higher potency. It was patented in 1981, and approved for medical use in 1993. It is marketed by Abbott Laboratories under the brand name Mavik. Side effects
Side effects reported for trandolapril include nausea, vomiting, diarrhea, headache, dry cough, dizziness or lightheadedness when sitting up or standing, hypotension, or fatigue. Possible drug interactions
Patients also on diuretics may experience an excessive reduction of blood pressure after initiation of therapy with trandolapril. It can reduce potassium loss caused by thiazide diuretics, and increase serum potassium when used alone. Therefore, hyperkalemia is a possible risk. Increased serum lithium levels can occur in patients who are also on lithium. Contraindications and precautions
Pregnancy and lactation
Trandolapril is teratogenic (US: pregnancy category D) and can cause birth defects and even death of the developing fetus. The highest risk to the fetus is during the second and third trimesters. When pregnancy is detected, trandolapril should be discontinued as soon as possible. Trandolapril should not be administered to nursing mothers. Additional effects
Combination therapy with paricalcitol and trandolapril has been found to reduce fibrosis in obstructive uropathy. Pharmacology
Trandolapril is a prodrug that is de-esterified to trandolaprilat. It is believed to exert its antihypertensive effect through the renin–angiotensin–aldosterone system.