Erythema skin reaction characterized

P-ARK An enzyme that phosphoylates the occupied form of a G-protein coupled receptor, e.g. the 6-adrenoceptor, leading to uncoupling of that receptor and desensitization. ARMI age-related memory impairment, arrhythmia (dysrhythmia) An abnormality of heart rhythm or rate of heartbeat, usually caused by disturbance of the electrical impulses and their conduction within the heart. They include ectopic beats (isolated irregular beats), tachycardias (too fast a heartbeat), bradycardias (too slow a heartbeat) and atrial flutter and ventricular fibrillation. Arthus reaction A severe local inflammatory response, a skin reaction characterized by erythema, oedema, necrosis, local haemorrhage. A type III hypersensitivity reaction. Arunlakshana and Schild plot See Schild plot, ascites fluid The fluid that accumulates in the peritoneal cavity during certain pathological conditions, aspiration The withdrawal of fluid or tissue from the body by suction. 

Acute toxic contact dermatitis may be induced by a single application of a toxic material. One local inflammatory skin reaction is characterized by erythema and oedema. This type of reaction occurs following contact with materials such as acids, alkalis, solvents, and cleansers and is rarely associated with topical application of medicinal or cosmetic products. In contrast, irritant contact dermatitis (a superficial non-immuno-logically based reaction) may occur after repeated exposure to many substances, including topical pharmaceutical agents. The reaction is usually localized to the site of exposure and usually diminishes after the stimulus has been removed. Some materials can stimulate an immune response following an initial topical application. Any future exposure may result in an inflammatory immune reaction, an allergic contact dermatitis, or sensitization. 

Adverse reactions Overall, the penicillins are well tolerated. The most common adverse effects are due to hypersensitivity reactions. Hypersensitivity reactions can be simply categorized as immediate reactions (type 1) or late reactions. Type 1 reactions are IgE mediated and are often associated with systemic manifestations such as diffuse erythema, pruritus, urticaria, angioedema, and bronchospasm. The most severe yet rare IgE-mediated side effect is anaphylaxis (0.05%). Type 1 reactions usually occur within 72 hr of administration. Late reactions usually occur 72 hr after drug administration. The most common late reactions include skin rashes characterized as maculopapular or morbilliform rashes. Rarely, nafcillin may cause neutropenia. Seizures in high doses, vaginal moniliasis, and Clostridium difficile infection also can occur with all penicillins... 

In the OECD test guideline for skin sensitization (OECD TG 406), the following definition is given Skin sensitization (allergic contact dermatitis) is an immunologically mediated cutaneous reaction to a substance. In the human, the responses may be characterized by pruritis, erythema, edema, papules, vesicles, bullae, or a combination of these. In other species, the reactions may differ and only erythema and edema may be seen. ... 

Urticaria, commonly known as hives, is a type I allergic reaction that results very rapidly from exposure to a toxicant to which the subject has become sensitized. It is characterized by the release of histamine from a type of white blood cell. Histamine causes many of the symptoms of allergic reaction, including tissue edema. In addition to edema, erythema, and accompanying raised welts on skin, urticaria is accompanied by severe itching. In severe cases, such as happen in some people as the result of bee or wasp stings, urticaria can result in systemic anaphylaxis, a potentially fatal allergic reaction. 

Direct irritation may thus be dehned as an adverse effect of chemicals directly applied to the skin that does not involve prior sensitization and thus initiation by an immune mechanism. Irritation is usually assessed by a local inflammatory response characterized by erythema (redness) and/or edema (swelling). Other responses may be present that do not elicit inflammation such as an increase in skin thickness. Irritant reactions may be classified as acute, cumulative, traumatic, or pustular. However, two classifications are generally used by toxicologists. Acute irritation is a local response of the skin usually caused by a single agent that induces a reversible inflammatory response. Cumulative irritation occurs after repeated exposures to the same compound and is the most common type of irritant dermatitis. 

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