Patient Education: Manufacturer provides a patient education brochure arteria music discount coumadin 5mg, "Important Facts About Your Chemotherapy arterial dissection cheap coumadin 1mg otc. Dose of loperamide prescribed for late diarrhea is higher than the usual dose recommendation pulse pressure klabunde buy 2 mg coumadin fast delivery. No change in the starting dose is recommended for elderly patients receiving the weekly dose schedule of irinotecan blood pressure for elderly order coumadin 1 mg line. Discontinue treatment with these agents at least 2 weeks before starting irinotecan. Nausea and vomiting occur in most patients and can be severe, may occur early (within 24 hours of administration) or late (more than 24 hours after administration). Renal impairment or failure has occurred usually in patients who became volume depleted from severe vomiting and/or diarrhea. In the event of an acute onset of new or progressive, unexplained pulmonary symptoms. If interstitial pulmonary disease is diagnosed, discontinue irinotecan and other chemotherapy and initiate appropriate treatment as needed. If no adverse reactions, administer a total dose of 2 mL (100 mg)/24 hr and repeat daily until results achieved or maximum calculated dosage reached (see dosage tables in literature or formula below). Iron replacement for blood loss: Dose should represent the equivalent amount of iron represented in blood loss. If no adverse reactions, calculate the desired dose with the following formula and administer the balance of the replacement dose over 2 to 3 daily doses: Amount of replacement iron (mg) 5 Blood loss (mL) 3 Hematocrit Calculated dose is in mg; convert to mL before administration. Formula is based on the approximation that 1 mL of normocytic, normochromic red cells contains 1 mg of elemental iron. Repeat daily until results achieved or maximum calculated dosage reached (see dosage tables in literature or the formula listed earlier). If no adverse reactions, administer the balance of the replacement dose over 2 to 3 daily doses. Iron dextran is removed from the plasma by cells of the reticuloendothelial system, which split the complex into its components of iron and dextran. Iron is immediately bound to protein moieties to form hemosiderin or ferritin, the physiologic forms of iron, or to a lesser extent to transferrin. Serum ferritin peaks approximately 7 to 9 days after iron dextran administration and slowly returns to baseline after about 3 weeks. Negligible amounts of iron are lost via the urinary or alimentary pathways after administration of iron dextran. Fatal reactions have occurred both after the test dose and in situations in which the test dose was tolerated. Administer in facilities equipped to monitor the patient and respond to any medical emergency. Patients with a history of drug allergy or multiple drug allergies may be at increased risk for anaphylactic-type reactions. Facilities for monitoring the patient and responding to any medical emergency must be readily available. They differ in chemical characteristics and may differ in clinical and adverse effects. The onset of these side effects is often delayed (1 to 2 days) and symptoms generally subside within 3 to 4 days. Unwarranted therapy may cause excess storage of iron and possible exogenous hemosiderosis. Maternal/Child: Category C: use only if absolutely necessary in pregnancy, breast-feeding, or childbearing years. Backache, dizziness, headache, itching, local phlebitis at injection site, malaise, nausea, rash, shivering, transitory paresthesias. Major: Anaphylaxis (fatalities have occurred); arthritic reactivation; dyspnea; febrile episodes; hypotension; leukocytosis; local phlebitis; lymphadenopathy; peripheral vascular flushing, especially with too-rapid injection; urticaria; tachycardia; shock (severe iron toxicity increases vasodilation and venous pooling and decreases circulating blood volume. Results in decreased cardiac output, hypotension, increased peripheral vascular resistance, and shock). May result in hemosiderosis, and excess iron may increase susceptibility to infection. If acute toxicity is seen, it may present as: Early: Abdominal pain, diarrhea, vomiting. Late: Bluish-colored lips, fingernails, and palms of hands; acidosis, drowsiness, shallow and rapid breathing, clammy skin, weak and fast heartbeat, hypotension, hypoglycemia, cardiovascular collapse. For severe symptoms, discontinue drug, treat hypersensitivity reactions, or resuscitate as necessary, and notify physician. Dialysis will not remove iron alone but will remove the iron deferoxamine complex and is indicated if oliguria or anuria is present. Repeat as needed to maintain target levels of hemoglobin, hematocrit, and laboratory parameters of iron stores within acceptable limits. Administer on 5 different days within a 14-day period to a total cumulative dose of 1,000 mg. Alternately, there is limited experience with administering a 500-mg dose on Day 1 and Day 14 as a 3. In dialysis patients, administer into the dialysis line during the dialysis session. Infusion in adults: this method of administration may reduce the risk of hypotensive episodes. Alternately may be given as an infusion equally distributed over at least 15 minutes. Has also been administered as an infusion in a 500-mg dose equally distributed over 3. Following intravenous administration, iron sucrose is dissociated by the reticuloendothelial system into iron and sucrose. Since iron disappearance from serum depends on the need for iron in the iron stores and iron-utilizing tissues of the body, serum clearance of iron is expected to be more rapid in iron deficient patients as compared to healthy individuals. Significant increases in serum iron and ferritin and significant decreases in total iron-binding capacity occur within 4 weeks of beginning iron sucrose treatment. Should not be used in patients with evidence of iron overload or in patients with anemia not caused by iron deficiency. Recumbent position during and after administration may help to prevent postural hypotension. Hypotensive effects may be additive to transient hypotension during dialysis and/or from too-rapid rate of administration. Safety and effectiveness for iron maintenance treatment has been established for pediatric patients 2 years of age and older. No causal relationship to drugs could be established; it may be a complication of prematurity in very-low-birth-weight infants. May reduce the absorption of concomitantly administered oral iron preparations, concurrent use not recommended. Other side effects varied according to the type of chronic kidney disease patient who is receiving iron sucrose. Pediatric patients: Arteriovenous fistula thrombosis, cough, dizziness, fever, headache, hypertension, hypotension, nausea, peritonitis, renal transplant, respiratory tract viral infection, and vomiting occurred. If acute toxicity is seen, it may present as abdominal and muscle pain, cardiovascular collapse, dizziness, dyspnea, edema, headache, hemosiderosis, hypotension, joint aches, nausea, pale eyes, paresthesia, sedation, vomiting. Recommended Isoproterenol Dose for Adults with Atropine-Resistant Hemodynamically Significant Bradycardia, Heart Block, Adams-Stokes Attacks, and Cardiac Arrest Route of Administration Bolus intravenous injection Intravenous infusion Preparation of Dilution Dilute 1 mL (0. Recommended Isoproterenol Dose for Adults with Bronchospasm Occurring During Anesthesia Route of Administration Bolus intravenous injection Preparation of Dilution Dilute 1 mL (0. Diagnosis of mitral regurgitation (unlabeled): 4 mcg/min as an infusion (1 mL/min of a 1250,000 dilution). Diagnosis of coronary artery disease or lesions (unlabeled): 1 to 3 mcg/min as an infusion (0. Lower-end initial doses may be appropriate in the elderly; consider the potential for decreased organ function and concomitant disease or drug therapy.
Renal blood pressure chart for child generic coumadin 1 mg with visa, hepatic pulse pressure locations buy 1 mg coumadin with visa, and hematopoietic function should be checked during prolonged therapy high blood pressure medication quinapril cheap coumadin 5mg with visa. Higher than normal doses may cause neurologic adverse reactions including convulsions heart attack 36 generic 5 mg coumadin with amex, especially with impaired renal function. Incidence of side effects increased in patients with viral infections or those taking allopurinol (Aloprim). For severe symptoms, discontinue the drug, treat hypersensitivity reactions (antihistamines, epinephrine, corticosteroids), and resuscitate as necessary. Skin and skin structure infections in pediatric patients over 1 year of age and less than 40 kg: 300 mg/kg/day (200 mg/kg ampicillin and 100 mg/kg sulbactam) in equally divided doses as an infusion every 6 hours (75 mg/kg every 6 hours). The American Academy of Pediatrics suggests use in pediatric patients over 1 month of age in the following doses. Mild to moderate infections: 150 to 225 mg/kg/day (100 to 150 mg/kg of ampicillin and 50 to 75 mg/kg sulbactam) in equally divided doses as an infusion every 6 hours (37. Severe infections: 300 to 450 mg/kg/day (200 to 300 mg/kg of ampicillin and 100 to 150 mg/kg of sulbactam) in equally divided doses as an infusion every 6 hours (75 mg/kg to 112. A broad-spectrum antibiotic and beta-lactamase inhibitor effective against selected gram-positive, gram-negative, and anaerobic organisms (see literature). Treatment of skin and skin structure and intra-abdominal and gynecologic infections due to susceptible strains of specific organisms. Known penicillin, cephalosporin (not absolute [see Precautions]), or beta-lactamase inhibitor sensitivity (not absolute [see Precautions]); infectious mononucleosis because of increased incidence of rash. Hypersensitivity reactions, including fatalities, have been reported in patients undergoing penicillin therapy; most likely to occur in patients with a history of penicillin allergy or sensitivity to multiple allergens. Consider in patients who present with diarrhea during or after treatment with ampicillin and sulbactam. Monitor: Watch for early symptoms of hypersensitivity reactions, especially in individuals with a history of allergic problems. Maternal/Child: Category B: studies in rabbits have not shown adverse effects on fertility or in the fetus. Burning, discomfort, and pain at injection site; diarrhea, rash, and thrombophlebitis occur most frequently. Higher than normal doses may cause neurologic adverse reactions, including convulsions; especially with impaired renal function. For severe symptoms, discontinue the drug, treat hypersensitivity reactions as indicated. In general, antifungal therapy should continue for at least 14 days after the last positive culture. Esophageal candidiasis: Begin with a loading dose of 100 mg as an infusion on Day 1. Treat for a minimum of 14 days and for at least 7 days following resolution of symptoms. Excursions for Manufacturer states, "Do not mix or co-infuse with other medications or electrolytes. A semi-synthetic lipopeptide, anidulafungin is an echinocandin, the newest class of antifungal agents. Acts by inhibiting the synthesis of 1,3-beta-d-glucan, an integral component of the fungal cell wall not present in mammalian cells. Treatment of the following fungal infections: candidemia and other forms of Candida infections (intra-abdominal abscess and peritonitis) and esophageal candidiasis. Limitation of use: Has not been studied in Candida infections associated with endocarditis, osteomyelitis, and meningitis. Patient Education: Promptly report any hypersensitivity or infusion-related reactions. Report S/S of liver dysfunction (anorexia, fatigue, jaundice, nausea and vomiting, dark urine, or pale stools). Maternal/Child: Category B: use during pregnancy only if benefits justify risk to fetus. Secreted in milk of drug-treated rats; not known if anidulafungin is secreted in human milk. If a hypersensitivity reaction occurs, discontinue anidulafungin and treat as indicated. S/S indicative of hepatic side effects may require evaluation of benefits versus risk of continuing anidulafungin therapy. Hemofil M, Monarc-M, Monoclate-P: From human plasma, immunoaffinity purified (ultrahigh purity). Recombinant products may be substituted for plasma-derived products without disrupting treatment regimen. A plasma antihemophilic factor level of about 30% of normal is needed for effective hemostasis when hemorrhage is present; greater percentages are required for surgical procedures, and only 5% to 10% of normal may be needed to control hemarthrosis. Usually requires 250 units daily in patients weighing less than 50 kg, 500 units daily in patients weighing more than 50 kg. Repeat infusion every 12 to 24 hours for 1 to 3 days until the bleeding episode as indicated by pain is resolved or healing is achieved. All preparations provide diluent and usually provide administration equipment, including needles (single- or double-ended), filters or filter needles, syringes, and/or administration sets for each vial. If more than one bottle is required for a dose, multiple bottles may be drawn into the same syringe; however, a new filter needle must be used to withdraw contents of each bottle of antihemophilic factor. Reduce rate of infusion or temporarily discontinue if there is a significant increase in pulse rate or S/S of hypersensitivity occur. Most preparations suggest beginning with a rate of 2 mL/min and increasing gradually up to 10 mL/min if appropriate. Other sources list the following information: Advate: A single dose over 5 minutes or less. Hemofil M, Monarc-M, and Recombinate: May be given at a rate not to exceed 10 mL/min. It is the specific clotting factor deficient in patients with hemophilia A (classic hemophilia) and can temporarily correct the coagulation defect in these patients. Purified using monoclonal antibody purification techniques, ion exchange chromatography, and immunoaffinity chromatography. Massive doses may cause acute hemolytic anemia, hyperfibrinogenemia, increased bleeding tendency, or jaundice (rare). Recombinant products: Arthralgia; asthenia; burning, erythema, and pruritus at injection site; chest discomfort; chills; cold feet; cough; diarrhea; dizziness; edema of lower extremities; fever; flushing; headache; hypotension (slight); increased sweating; lethargy; nausea; rash; sore throat; or an unusual taste in the mouth may occur. Most side effects usually subside spontaneously in 15 to 20 minutes and are generally related to the rate of infusion. Slow or discontinue infusion temporarily if pulse rate increases or beginning S/S of hypersensitivity reactions occur. Discontinue immediately and treat hypersensitivity reactions (antihistamines, epinephrine, corticosteroids). Repeat doses are administered as needed based on monitoring of appropriate clinical and laboratory measures. Oral surgery is defined as removal of fewer than three teeth, if the teeth are non-molars and have no bony involvement. At least one maintenance dose following surgery based on individual pharmacokinetic values. Consult individual product instructions in the package insert; each product has a specific process for dilution. Alphanate provides diluent, a double-ended transfer needle, and a microaggregate filter for use in administration. Alphanate and Humate-P: Do not refrigerate after re- Specific information not available. It is the specific clotting factor deficient in patients with hemophilia A (classic hemophilia). Antihemophilic factor/von Willebrand Factor Complex is obtained from pooled human fresh-frozen plasma.
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Absorption arteria ulnar coumadin 1 mg discount, fate and excretion: Oral absorption is slow; overall bioavailability however arrhythmia basics purchase coumadin 5 mg online, approaches 90% arrhythmia in 7 year old coumadin 1mg with amex. The plasma half-life arrhythmia omega 3 fatty acids coumadin 2mg with amex, initially 24-36 hours, falls to around 12 hours on chronic dosing because of autoinduction. It is a potent hepatic microsomal enzyme inducer and accelerates its own metabolism as well as that of many other lipid soluble drugs. However, it can cause nausea, anorexia, giddiness, vomiting, ataxia, mental confusion and skin rash. The rare but serious toxic effects reported include obstructive jaundice, peripheral neuritis, agranulocytosis, thrombocytopenia and aplastic anaemia. Long term use of carbamazepine may cause fluid retention and insidious development of sluggishness, both mental and physical. The loss of physical and mental drive can be so gradual that the patient and the family may wrongly attribute it to the normal process of ageing. The initial dose is 100 mg bid, gradually increased to 6001200 mg per day in divided doses in temporal lobe epilepsy and to 400-800 mg in neuralgias. Oxcarbazepine, a prodrug, has similar activity and therapeutic uses as carbamazepine but it is more expensive. Its active metabolite is a s- isomer, eslicarbazepine, which is also available as prodrug, eslicarbazepine acetate. However, it is used only for focal seizures as an add on therapy to be given as single dose. Both, oxcarbazepine and eslicarbazepine are selective inducers of cytochrome isoenzyme that metabolises estrogens. Pharmacological actions: It is effective only in petit mal epilepsy It does not induce liver. About 20% is excreted unchanged in the urine and the rest is metabolised by the liver. Adverse reactions: these comprise anorexia, nausea, vomiting, drowsiness, dizziness and occasionally parkinsonism. Preparations and dosage: It is available as 250 mg capsules and as a syrup (250 mg per 5 ml). The usual starting dose is 250 mg per day in children, increased by 250 mg at weekly intervals till the seizures are controlled. Therapeutic uses: It is the drug of choice in petit mal epilepsy Additional drug(s) are. In patients with both petit mal and grand mal seizures, sodium valproate may be the drug of choice as it is able to control both types of seizures. It is also used in myoclonic seizures and with variable success in akinetic seizures and infantile spasms. Absorption, fate and excretion: Sodium valproate is rapidly and almost completely absorbed after oral administration. Hence it is advisable to do baseline hepatic function studies before starting sodium valproate. The other infrequent adverse effects are sedation, ataxia, incoordination, thrombocytopenia and pancreatitis. Sodium valproate inhibits platelet aggregation, although this is unlikely to be of clinical significance unless the patient is also on other drugs that affect coagulation. Thus it inhibits its own metabolism and that of lamotrigine, phenobarbitone, phenytoin and carbamazepine, and may enhance their toxicity. Preparations and dosage: Sodium valproate 100 and 200 mg tablets; syrup 200 mg per 5 ml Therapy is initiated 10 mg/kg/day in two divided doses. This is increased by 5 to 10 mg/kg/day at weekly intervals upto 20-30 mg/kg/day Doses as high as 60 mg/kg/day have. The adverse effects are weight gain, drowsiness, depression, memory disturbances, diplopia and constriction of visual fields. Attacks of acute behavioral changes in some patients is a major disadvantage and the drug should be avoided in patients with mental illness. The, drug is extensively metabolised in the liver and has a half-life of 7 to 9 hours. The drug is mainly used as an "add on" drug for the treatment of partial seizures, with or without secondary generalisation in adolescents and adults. The drug is well absorbed orally; is not protein bound; does not get metabolised and is excreted unchanged in the urine. Concurrent use of gabapentin does not affect the blood levels of other antiepileptic drugs. It usually causes mild to moderate somnolence, dizziness, ataxia, fatigue, edema, blurred vision, vertigo which can interfere with activities like driving. Gabapentin is used in combination with other drugs, in partial seizures with or without secondary generalisation, resistant to other drug therapy It is administered in the dose of. Pregabalin: this drug, related chemically to gabapentin, has similar mechanism of action and uses. Both the drugs have also been used in the treatment of migraine, deafferentiation pain such as post-herpetic neuralgia and diabetic neuropathy restless leg syndrome and in, bipolar disorders with variable benefits. Benzodiazepines are not a good choice for the long term treatment of epilepsy because: (a) Tolerance can develop and seizures may recur within few months. Because of its high lipid solubility and good penetration into the brain, it has a very rapid onset of action. Midazolam and lorazepam are used as anticonvulsants in emergency such as status epilepticus. In petit mal, it is used in patients who do not respond to ethosuximide and sodium valproate and not as the primary drug. Tolerance develops and breakthrough seizures may occur after 1 to 2 months of therapy It has also been used as an adjunct to . The serious adverse effects are mainly neurological and comprise drowsiness, ataxia, personality changes, slurred speech, tremor, vertigo and confusion. It is liable to cause respiratory depression and to increase the salivary and bronchial secretions. Tolerance is known to occur and psychic and physical dependence have been reported. Therapy is initiated in adults and in children over 10 years of age with oral administration of 0. X Miscellaneous: Lamotrigine, topiramate, levetiracetam, zonisamide and lacosamide are considered as broad spectrum as they are useful in both, focal and generalised seizures. Given orally it is almost, completely absorbed and is eliminated mainly by hepatic metabolism. It is used as an add-on drug in patients with resistant focal and secondarily generalised seizures. Due to its membrane stabilising action, it is used in the treatment of deafferentiation pain. It is used in the dose of 50 mg bid, increased gradually to 200 mg per day Valproic acid inhibits its metabolism and hence in patients taking valproate, the dose. It is claimed to be useful in chronic alcohol addicts as an anti-craving drug and also as antiobesity drug. It is effective in the kindling animal model but has no effect on the electroshock or pentylenetetrazole induced seizures. Given orally it is absorbed rapidly and completely It is not bound to plasma proteins. Hence, it is wise to monitor carefully, patients prone to psychiatric disturbances. It is used as a add-on drug to treat refractory myoclonic, or focal seizures and uncontrolled generalised tonic- clonic seizures. Zonisamide: this sulfonamide derivative inhibits T type Ca++ currents and like phenytoin delays the recovery of the inactivated Na+ channels. The adverse effects include dose dependent dizziness, headache, fatigue, ataxia and vomiting. Its efficacy for partial onset seizures is similar to other drugs and is used as add-on drug in resistant cases. Rufinamide, a triazole derivative, has been shown to reduce tonic-atonic seizure frequency by enhancing slow inactivation of voltage gated Na+ channels. It is used as an adjunct in treatment of seizures in children with Lennox-Gastaut syndrome.
Changes in K+ distribution may cause serious arrhythmias in patients on diuretics and digitalis arteria hepatica propia coumadin 2 mg lowest price. Presence of a hereditary abnormal plasma pseudocholinesterase blood pressure chart 15 year old generic coumadin 5 mg otc, having a poor ability to hydrolyse succinylcholine blood pressure simulator order 2mg coumadin amex, or acquired deficiency of normal pseudocholinesterase as in liver disease pulse pressure equivalent purchase coumadin 1 mg otc, predisposes to its development. When the procedure involved is of short duration, succinylcholine or mivacurium is the drug of choice. Local injection of the toxin weakens the overactive muscle and decreases the hypersecretion of glands innervated by cholinergic neurons. It has been used to treat: (1) Spastic conditions such as spasmodic torticolis, hemifacial spasm, strabismus, blepharospasm, dystonias, lower esophageal spasm and painful anal fissure; (2) Wrinkles on the face and neck; (3) Palmar hyperhidrosis. Adverse reactions include ptosis, diplopia, reduced blinking leading to dry eyes, minor bruises and lid swelling; reversible muscle atrophy can occur after repeated administration. Botulinum toxin Type B can be used in patients who have become resistant to Type A toxin. Given orally it is incompletely, (about 1/3rd) absorbed and is largely metabolised in the liver. Adverse reactions: these include generalised muscle weakness, dizziness, drowsiness, fatigue and diarrhoea. Patients in whom spastic, dystonic stiffness is useful as a sort of protective endogenous crutch should not be treated with dantrolene. It must be noted that management of the patient with spasticity implies more than just treatment of the spasticity. Active measures to reduce spasticity are only justified where the reflex hyperexcitability interferes with function, making rehabilitation, physiotherapy and nursing care difficult. The compound was isolated from ergot extracts by Barger and Dale in 1910 and reports regarding its pharmacological actions were published by Dale and Laidlaw in 1910-1911. The role of this extremely potent natural substance in the genesis of allergic and anaphylactic manifestations was forecast by the brilliant work of Lewis. Distribution and synthesis: Histamine, an imidazole compound, is widely distributed in plant and animal tissues, and is also present in the venom of bees and wasps. Almost all tissues in mammals synthesise histamine, from amino acid histidine by decarboxylation with the help of histidine decarboxylase (Fig 23. Very little, however, reaches the circulation as most of what is absorbed is rapidly metabolised in the intestinal wall and the liver. These cells possess histidine decarboxylase, and also contain specialised granules, wherein histamine is stored in an inactive form. Within the gut, the histamine concentration is highest in the stomach wall and gastric and intestinal glands. Mechanism of action: Four types of receptors, H1, H2, H3 and H4 have been identified and cloned. In the tissues, histamine serves as a chemotactic agent for neutrophils and eosinophils. H1 receptor effects can be competitively blocked specifically by the conventional antihistaminics (H1 receptor blockers). Impromidine is a potent H2 receptor agonist and behaves as a competitive antagonist at the autoinhibitory receptors. Both H1 and H2 receptors appear to be involved in vascular dilatation, hypotension and edema formation. In man, the pulmonary vessels are dilated by histamine, producing a fall in pulmonary artery pressure. The headache is attributed to stretching of sensory nerve endings around the cranial arteries. In man, histamine causes marked flushing, a sense of warmth; and marked increase in capillary permeability after large doses, which causes edema and reduction in plasma volume. Histamine-induced hypotension can be prevented but only partially reversed by antihistaminic agents. Triple response: When a pointed object is drawn lightly over the skin, the stroke line becomes blanched, i. The triple response (Lewis response) is a part of the normal reaction to injury Its. Smooth muscle: Histamine stimulates the smooth muscle of various tissues directly (H1 action). Individuals suffering from bronchial asthma and certain other pulmonary diseases develop a sharp fall in vital capacity and considerable respiratory embarrassment in response to histamine. Histamine-induced bronchospasm is antagonised by adrenaline, isoprenaline and aminophylline but not by antihistaminics or atropine. Histamine, through H1-receptors, causes gall bladder contraction while H2-receptors mediate gall bladder relaxation. Exocrine glands: Histamine is an important physiological mediator of gastric acid secretion. The histamine receptors in the brain mediate the actions of locally synthesised, stored and released histamine. There are two types of histamine containing cells in the brain: (1) Histaminergic neurons and (2) Mast cells. Histamine is thought to be a waking amine within the brain and is believed to act by "increasing the sensitivity of large cerebral areas to excitatory inputs". Histamine also modulates the release of neurotransmitters via presynaptic H3 receptors located on histaminergic and non-histaminergic neurons in the central and peripheral nervous systems. Immunomodulation: All the four histamine receptors are involved in immunomodulation (Table 23. Miscellaneous actions: Histamine, on intra-epidermal injection, evokes itching and pain. Histamine has an effect on lymphocytes via H2 receptors and it also inhibits the secretory activity of the mast cells and the basophils by a negative feedback via H3 receptors. Absorption, fate and excretion: Histamine is a very stable compound and is absorbed from all sites. However, only a small quantity of oral histamine reaches the circulation because of its first pass metabolism. Histamine metabolism varies according to the animal species, sex and the organ studied. In some species like rats, it is mainly metabolised by oxidative deamination by the enzyme diamine oxidase (histaminase) present in the liver, kidney and intestinal mucosa. Adverse reactions: these are due to its pharmacological actions and include hypotension, flushing, angioedema, headache, visual disturbances, diarrhoea and dyspnea due to bronchospasm. Man and guinea pig are extremely sensitive to histamine while rats and mice are highly resistant. Large quantities of histamine may be formed by bacteria in the small intestine acting on spoiled fish which may have high histidine content. Similar reaction may be observed in susceptible subjects after consumption of red wine. The drug causes vasodilatation and improves blood flow to the labyrinth and brainstem. Histamine liberators: Various agents can release tissue histamine and may thus cause histamine reactions. Histamine, Anaphylaxis and Allergy the term anaphylaxis is used clinically to describe a medical emergency caused by allergy to a variety of agents such as drugs, foods, plants, chemicals, latex and insect/reptile bites. It is mediated by IgE (Chapter 2), and histamine is the most important mediator involved in it. The clinical features in man are due to laryngeal edema, bronchospasm and hypotension (anaphylactic shock). An anaphylactic reaction may progress either slowly or rapidly the latter especially after parenteral drug administration.
