2.
Vomiting:-Vomiting
is defined as the ejection or expulsion of gastric contents through the mouth,
often requiring a forceful event (reflexive).
3.
Chemotherapy: - In the original sense, a chemical that binds to and
specifically kills microbes or tumor cells.
The term chemotherapy was coined in this regard by Paul Ehrlich (1854-1915).
4.
Chemotherapy induced nausea and vomiting:
Among patients with cancer,
chemotherapy-induced nausea and vomiting (CINV) is a common adverse effect that
not only impacts quality of life, but also treatment outcomes. It is important
to address these issues from both prevention and treatment standpoints so that
patients remain adherent to their regimens. With CINV being classified into 5
different types, the primary medication options for prevention and treatment
include 5-HT3 receptor antagonists, NK1 receptor antagonists, and
corticosteroids. Other medications used, but to a lesser extent, include
dopamine antagonists, benzodiazepines, cannabinoids, and olanzapine. In
addition, those patients who express interest in alternative or
nonpharmacological therapies may have options as well. With the array of
medications available for patients with cancer, pharmacists play an integral
role in optimizing patient outcomes. Therefore, it is important that
pharmacists stay up-to-date on the most current guidelines available for CINV
treatment.
5.
Emesis:
Emesis is an anatomically complex reflex which prevents
intoxication through gastrointestinal (GI) absorption.
The emetic reflex arc
is
responsive to a wide variety
and time-course of
perturbations, and thus
requires extensive integration
of sensory afferents
to generate one
complex motor pattern. Chemotherapy-induced nausea and vomiting (CINV) are two
of the most common and troublesome
side effects experienced by cancer patients.
a) The CNS plays a critical role in the
pathophysiology of CINV, by receiving and processing a variety of emetic
stimuli and then generating and sending efferent signals to a number of
organs and tissues, which result in nausea
and vomiting. Advances have been made in the treatment of acute
chemotherapy induced vomiting (CIV), chemotherapy-induced nausea (CIN),
anticipatory nausea and vomiting (ANV) and delayed nausea and vomiting (DNV)
remain substantial challenges for cancer patients.
b)
The
central and peripheral regions include:-
a)
The
emetic or vomiting center (VC), which is the primary structure for coordinating
nausea and vomiting and includes a collection of neurons within the medulla oblongata
b) The chemoreceptor trigger zone (CTZ)
in the area postrema located at the floor of the fourth ventricle of the brain.
c)
The
vagal nerve afferents that project from the gastrointestinal (GI) tract to the
nucleus of the solitary tract (NTS) and the dorsal motor nucleus of the vagus and
iv)
the enterochromaffin cells (EC) in the
GI tract.
c) Nausea and Vomiting Induced by the
Tumor Brain tumor: it is the result
of increased intracranial pressure. Malignant bowel obstruction as in colorectal, ovarian and peritoneal
cancer: vomiting is an early symptom
in high obstruction Metabolic:
hypercalcemia, polyuria, and nocturia. Blood biochemistry will confirm the diagnosis.
d)
Anticipatory
nausea is reported by 30% of
patients who experienced nausea during earlier chemotherapy cycles.
Anticipatory vomiting is reported by
20% who experienced vomiting during earlier chemotherapy treatment cycles ,
Anticipatory, acute and delayed CINV lead to poorer
chemotherapy adherence, impaired function peripheral centers, neurotransmitters
and receptors. SP is a well-known primary neurotransmitter in signaling of various noxious stimuli
via NK1 receptors.
Serotonin (5-HT), Dopamine (DA),
Substance P (SP), and certain prostanoids are proemetic. The 5-HT3 receptor is an ionotropic ligand-gated ion channel (LGIC) and thereby differs
from other serotonin receptors whose actions are mediated via G-proteins. The
structure and function of 5-HT3 receptors shows they are members of the
Cys-loop family of LGICs, which includes glycine, GABAA and nicotinic
acetylcholine (nACh) receptors.
6.
Categories of Nausea And
Vomiting
The Classification of
Chemotherapy-Induced Nausea and Vomiting (CINV) is depicted in the in the
a) Acute
Onset Nausea and Vomiting: Occurring
within 24 hours of initial administration of
chemotherapy. Mainly by serotonin (5-HT) release from the enterochromaffin cells.
b) Delayed
Onset Nausea and Vomiting: After
24 hours to 5 days after chemotherapy. Various mechanism - Mainly substance P
mediated disruption of the blood - brain barrier, disruption of the
gastrointestinal motility, adrenal hormones.
Anticipatory Nausea and Vomiting: Occurrence is possible after 1 cycle of chemotherapy. Involves an element of classic conditioning. Triggered by taste, odour, sight, thoughts or anxiety secondary to a history of poor response to antiemetic agents.
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