Vomiting and nausea

Specific etiologies associated with nausea and vomiting are presented in Table 27-1. 

The three consecutive phases of emesis include nausea, retching, and vomiting. Nausea, the imminent need to vomit, is associated with gastric stasis. Retching is the labored movement of abdominal and thoracic muscles before vomiting. The final phase of emesis is vomiting, the forceful expulsion of gastric contents due to GI retroperistalsis. 

The CTZ, located in the area postrema of the fourth ventricle of the brain, is a major chemosensory organ for emesis and is usually associated with chemically induced vomiting. 

Numerous neurotransmitter receptors are located in the vomiting center, CTZ, and GI tract. Examples of such receptors include cholinergic and histaminic, dopaminergic, opiate, serotonin, neurokinin (NK), and benzodiazepine receptors. Theoretically, chemotherapeutic agents, their metabolites, or other emetic compounds trigger the process of emesis through stimulation of one or more of these receptors. 

Mechanical obstruction Diabetes mellitus (diabetic ketoacidosis) 

Marijuana has been used effectively to treat the nausea and vomiting often associated with chemotherapy in the treatment of cancer. 

Marijuana use often causes long-term damage to the cardiovascular system. 

Cannabis saliva, more commonly known as marijuana, is a hemp plant that grows freely throughout the world. The cannabis plant is known most commonly today as a potent psychoactive substance, but for many years it was harvested primarily for its fiber. These strong hemp fibers were employed in the production of rope, clothes, and ship -sails. Although cannabis was used for several centuries in other parts of the world for its mind-altering properties, it was not until the first third of this century that its psychoactivc properties were recognized in the United States. Then the hemp plant was more often harvested for its psychoactive effects. 

The term marijuana is thought to be based on the Portuguese word mari uan o, which translates as intoxicant. Marijuana, incidentally, is not the same as hashish, although both arc derived from the Cannabis saliva plant. Marijuana is the leafy top portion of the plant, whereas hashish is made from the dust of the resin that the hemp plant produces to protect it from the sun and heat and to maintain hydration. Plants that grow in warmer climates produce greater amounts of the resin, which generally has stronger psychoactivc effects. 

We begin this chapter with a historical overview of marijuana and its use through the centuries. This is followed by a section on the epidemiology of current marijuana use. Next we provide information on absorption, distribution, metabolism, and excretion mechanisms of action and tolerance and dependence. Follow ing this is an overview of the medical and p-sychotherapeutic uses of marijuana. The chapter s final sections concern the physical, psychological, and social/environmental effects of marijuana. 

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This compound has antihistaminic activity and is usehil in the therapy of motion sickness. It may also be effective in the control of post-operative nausea and vomiting. It is classified as FDA Category B for Pregnancy, ie, no demonstrated risks shown in animal studies however, no controlled trials in pregnant women. Large doses may cause drowsiness and dry mouth owing to decreased secretion of saUva. 

Dronabinol is indicated for the treatment of the nausea and vomiting produced by cancer chemotherapy in patients who have failed to respond adequately to other conventional treatments. This agent may be habit forming and can be expected to produce disturbing psychomimetic reactions. It should only be used under close supervision. 

Morphine has certain undesirable side effects. Among these are respiratory depression, nausea, and vomiting, depression of the cough reflex, cardiovascular depression and hypotension, smooth muscle contraction (constipation), and histamine release (93). Morphine s onset of action, duration, and low therapeutic indices have prompted a search for a more effective opiate iv anesthetic. Extreme simplification of the complex morphine molecule has resulted in anilido —piperidines, the fentanyl class of extremely potent opiate iv anesthetics (118,119). 

The most significant occupational exposures to zinc would occur during the smelting and refining of zinc ore. The standards for occupational exposure have been estabUshed at a level to prevent the onset of metal fume fever. This temporary condition is caused by excessive exposure to freshly formed fumes of zinc oxide and results in flulike symptoms of fever, chills, headache, muscle pain, nausea and vomiting. 

A Chinese traditional herbal treatment for malaria obtained from the roots of Dichroafebrifuga is called Ch ang Shan and was investigated in the 1940s. Febrifugine (80), the alkaloid responsible for its activity, was isolated and found to be considerably more active than quinine in experimental infections. Unfortunately, the dmg caused nausea and vomiting in humans. Synthesized analogues were generally less effective than the parent. 

Trichloroethylene is acutely toxic, primarily because of its anesthetic effect on the central nervous system. Exposure to high vapor concentrations is likely to cause headache, vertigo, tremors, nausea and vomiting, fatigue, intoxication, unconsciousness, and even death. Because it is widely used, its physiological effects have been extensively studied. 

Under conditions of normal use, detergent products are not lia2ardous to users. Nonetheless, surfactants possess some toxicity, and they are mild irritants. Particularly under conditions of misuse, such as accidental ingestion or spillage, they can produce irritation and discomfort in the form of nausea and vomiting, as well as irritation to skin and eyes. The long-term effects, however, are minimal (134). 

Dacarbazine is the most active compound used for treating metastatic melanoma. It is also combined with anthracyclines and other cytostatics in the treatment of different sarcomas and Hodgkin s disease. Dacarbazine may cause severe nausea and vomiting. Myelosuppres-sion results in leukopenia and thrombocytopenia. Alopecia and transient abnormalities in renal and hepatic function also occur. 

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