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Astigmatism is the most common vision problem. It may accompany nearsightedness or farsightedness. It is usually caused by an irregularly shaped cornea, but sometimes it is the result of an irregularly shaped lens. Either type can be corrected by eyeglasses, contact lenses, or refractive surgery.
The average person is easily confused by the terms pharmaceutics and pharmacology, thinking they are one and the same. Whereas pharmaceutics is the science of preparing and dispensing drugs (otherwise known as the science of pharmacy), pharmacology is the study of medications.
Sildenafil (Viagra®) has two actions that may be of consequence in patients with heart disease. It can lower the blood pressure, and it can interact with nitrates. It should never be used in patients who are taking nitrates.
In most climates, 8 to 10 glasses of water per day is recommended for adults. The best indicator for adequate fluid intake is frequent, clear urination.
Disorders that may affect pharmacodynamics include genetic mutations, malnutrition, thyrotoxicosis, myasthenia gravis, Parkinson's disease, and certain forms of insulin-resistant diabetes mellitus.