AJUSTE REMUNERACIONAL PARA PERSONAL DE FUERZAS DE ORDEN Y SEGURIDAD PÚBLICA
2.3. Oficio de Cámara Revisora a Cámara de Origen
in the Dosages table on p. 112.
The most common manifestation of untreated cyano- cobalamin deficiency is pernicious anemia leading to megaloblastic anemia and irreversible neurological dam- age. The use of vitamin B12 to treat pernicious anemia and other megaloblastic anemias results in a rapid conver- sion of a megaloblastic bone marrow to a normoblastic bone marrow. The preferred route of administration of vitamin B12 in treating megaloblastic anemias is by deep intramuscular injection. Cyanocobalamin is also use- ful in the treatment of pernicious anemia caused by an endogenous lack of intrinsic factor.
Contraindications
The only usual contraindication to administration of extrinsic cyanocobalamin (vitamin B12) is known drug product allergies. This may include sensitivity to the chemical element cobalt, which is part of the structure of cyanocobalamin. Other contraindications include heredi- tary optic nerve atrophy (Leber’s disease).
Adverse Effects
Vitamin B12 is nontoxic and large doses must be ingested to produce adverse effects, which include itching,
FIG. 8-3 The oral absorption of cyanocobalamin requires the presence of the intrinsic factor secreted by gastric parietal cells.
Extrinsic-Intrinsi c Factor Complex Extrinsic Factor
Cyanocobalamin (from the diet)
Intrinsic Factor Gastric intrinsic factor
(from parietal cells)
Absorption from intestines into
body
cyanocobalamin
Cyanocobalamin (vitamin B12) is a water-soluble B- complex vitamin required for maintaining body fat and carbohydrate metabolism and protein synthesis. It is also needed for growth, cell replication, blood cell pro- duction, and the integrity of normal nerve function. Cyanocobalamin is available both as OTC preparations and by prescription. Most of the OTC cyanocobalamin- containing products are multivitamin preparations,
whereas many of the sole cyanocobalamin-containing products contain large doses for parenteral injection and are available by prescription only. Cyanocobalamin is pregnancy category A.
PHARMACOKINETICS
Half-Life Onset Peak Duration
6 days Unknown Plasma: 8–12 hr Unknown TABLE
8-9
Cyanocobalamin: Adverse Effects
Body System Adverse Effects
Cardiovascular Central nervous
Heart failure, peripheral, vascular thrombosis, pulmonary edema Flushing, optic nerve atrophy Gastrointestinal Diarrhea
Integumentary Itching, rash, pain at injection site Metabolic Hypokalemia
Vitamins and Minerals CHAPTER 8
123
essential for the production of hemoglobin, which is neces- sary for oxygen transport throughout the body (Chapter 56). Minerals are required for muscle contraction, nerve transmission, and the makeup of essential enzymes.
Mineral compounds are composed of metallic and nonmetallic elements that are chemically combined with ionic bonds. When these compounds are dissolved in
M I N E R A L S
Minerals are essential nutrients that are classified as inorganic compounds. They act as building blocks for many body structures and thus are necessary for a variety of physiological functions. They are also needed for intra- cellular and extracellular body fluid electrolytes. Iron is
V I T A M I N C
Vitamin C (ascorbic acid) can be synthesized for use as a drug and is used in many therapeutic situations. Prolonged ascorbic acid deficiency results in the nutri- tional disease scurvy, which is characterized by weak- ness, edema, gingivitis and bleeding gums, loss of teeth, anemia, subcutaneous hemorrhage, bone lesions, delayed healing of soft tissues and bones, and hardening of leg muscles. Scurvy was recognized for several centur- ies, especially among sailors. In 1795, the British navy ordered ingestion of limes to prevent the disease.
Mechanism of Action and Drug Effects
Vitamin C is reversibly oxidized to dehydroascorbic acid in the body, and it acts in oxidation-reduction reactions. It is required for several important metabolic activities, including collagen synthesis and the maintenance of con- nective tissue; tissue repair; maintenance of bone, teeth, and capillaries; and folic acid metabolism (specifically, the conversion of folic acid into its active metabolite). It is also essential for erythropoiesis. Vitamin C enhances the absorption of iron and is required for the synthesis of lipids, proteins, and steroids. It has also been shown to aid in cellular respiration and resistance to infections.
Indications
Vitamin C is used to treat diseases associated with vita- min C deficiency and as a dietary supplement. It is most beneficial in patients who require larger daily require- ments because of pregnancy, lactation, hyperthyroidism, fever, stress, infection, trauma, burns, smoking, exposure to cold temperatures, and the consumption of certain drugs (e.g., estrogens, oral contraceptives, barbiturates, tetracyclines, and salicylates). Because vitamin C is an acid, it can also be used as a urinary acidifier. The benefits
of other uses of vitamin C are less well documented. For example, taking vitamin C to prevent or treat the com- mon cold is common practice. However, most large con- trolled studies have shown that ascorbic acid has little or no value as a prophylactic for the common cold.
Contraindications
The only usual contraindication for vitamin C use is known allergy to a specific vitamin product.
Adverse Effects
Vitamin C is usually nontoxic unless excessive dosages are consumed. Megadoses can produce nausea, vomit- ing, headache, and abdominal cramps and will acidify the urine, resulting in the formation of cystine, oxalate, and urate kidney stones. Furthermore, individuals who discontinue taking excessive daily doses of ascorbic acid can suffer from scurvy-like symptoms.
Interactions
Ascorbic acid has the potential to interact with many classes of drugs. However, clinical experience concern- ing many interactions is inconclusive. For example, it has been reported that ascorbic acid can decrease the effect- iveness of oral anticoagulants. This does not always hap- pen, but practitioners should be aware of this possibility. Coadministration with acid-labile drugs such as penicil- lin G or erythromycin should be avoided. As previously mentioned, vitamin C can acidify the urine. This usually requires large doses for a significant effect but can enhance the excretion of basic drugs and delay the excretion of acidic drugs. Either outcome may sometimes be desirable.
Dosages
Commonly recommended dosages for vitamin C are listed in the Dosages table on p. 112.
ascorbic acid
Ascorbic acid (vitamin C) is a water-soluble vitamin required for the prevention and treatment of scurvy. As previously explained, it is also required for erythropoi- esis and the synthesis of lipids, protein, and steroids. It is available both in OTC preparations such as multivitamin products and by prescription. Ascorbic acid is available in
many oral dosage forms and as an injectable form. It is pregnancy category A.
PHARMACOKINETICS
Half-Life Onset Peak Duration
124
PART ONE Pharmacology Basicswater, they separate (dissociate) into positively charged metallic cations and electrolytes or negatively charged nonmetallic anions and electrolytes (Figure 8-4).
Ingestion of mineral nutrients provides essential ele- ments necessary for vital bodily functions. Elements required in larger amounts are called macrominerals; those required in smaller amounts are called microminerals or trace elements. Table 8-10 lists the classification of nutrient elements as either macrominerals or microminerals and as metal or nonmetal.
C A L C I U M
Calcium is the most abundant mineral element in the human body, accounting for approximately 2% of the total body weight. The highest concentration of calcium is in bones and teeth. The efficient absorption of calcium requires adequate amounts of vitamin D.
Calcium deficiency results in hypocalcemia and affects many bodily functions. Causes of calcium deficiency include inadequate calcium intake and insufficient vita- min D to facilitate absorption; hypoparathyroidism; and malabsorption syndrome, especially in older adults. Calcium deficiency–related disorders include infantile rickets, adult osteomalacia, muscle cramps, osteoporosis (especially in postmenopausal women), hypothyroidism, and renal dysfunction. Table 8-11 lists the possible causes of calcium deficiency and the resulting disorders.
Mechanism of Action and Drug Effects
Calcium is essential for the normal maintenance and function of the nervous, muscular, and skeletal systems and for cell membrane and capillary permeability. Cal- cium participates in a variety of essential physiological
functions, including transmission of nerve impulses; contraction of heart, smooth, and skeletal muscles; and enzymatic reactions. Calcium is essential in many physiological processes, including transmission of nerve impulses, renal function, respiration, and as a catalyst for many of the coagulation pathways in the blood. It acts as a cofactor in clotting reactions involving the intrinsic and extrinsic pathways of thromboplastin. It is also a cofactor in the conversion of prothrombin to thrombin by thromboplastin and the conversion of fibrinogen to fibrin. Calcium plays a regulatory role in the release and storage of neurotransmitters and hormones, in white blood cell (WBC) and hormone activity, in the uptake and binding of amino acids, and in intestinal absorption of cyanocobalamin (vitamin B12) and gastrin secretion.
Indications
Calcium salts are used as a source of calcium cations for the treatment or prevention of calcium depletion in patients for whom dietary measures are inadequate. FIG. 8-4 When mineral compounds are dissolved in water, they separate into positively charged metallic cations or negatively charged nonmetallic anions and electrolytes.
Nonmetallic elements Metallic elements
Positively charged metallic cations
Electrolytes
Electrolytes
Negatively charged nonmetallic anions
TABLE
8-10
Mineral Elements
Element Symbol Type Ionic/Electrolyte Form
MACROMINERALS
Calcium* Ca Metal Ca12 calcium cation
Chlorine Cl Nonmetal Cl1− chloride anion
Magnesium* Mg Metal Mg2+ magnesium cation
Phosphorus* P Nonmetal PO4
3− phosphate anion
Potassium K Metal K1+ potassium cation
Sodium Na Metal Na1+ sodium cation
Sulfur S Nonmetal SO4
2− sulfate anion MICROMINERALS
Chromium Cr Metal Cr3− chromium cation
Cobalt Co Metal Co2+ cobalt cation
Copper Cu Metal Cu2+ copper cation
Fluorine F Nonmetal F1− fluoride anion
Iodine* I Nonmetal I1− iodide anion
Iron* Fe Metal Fe2+ ferrous cation
Manganese Mn Metal Mn2+ manganese cation
Molybdenum Mo Metal Mo6+ molybdenum cation
Selenium* Se Metal Se14+ selenium cation
Zinc* Zn Metal Zn2+ zinc cation
Vitamins and Minerals CHAPTER 8
125
Calcium requirements are also high for growing children and for women who are pregnant or breastfeeding. Many conditions may be associated with calcium deficiency: • Achlorhydria alkalosis • Chronic diarrhea • Hyperphosphatemia • Hypoparathyroidism • Menopause • Pancreatitis
• Pregnancy and lactation • Premenstrual syndrome (PMS) • Renal failure
• Sprue steatorrhea • Vitamin D deficiency
Calcium is also used to treat manifestations of established deficiency states, including adult osteomalacia, hypo- thyroidism, infantile rickets or tetany, muscle cramps, osteoporosis, and renal insufficiency. It is used as a dietary supplement for women during pregnancy and lactation.
There are many different selected calcium salts avail- able for treatment or nutritional supplementation. Each calcium salt contains a different amount of elemental cal- cium per gram of calcium salt. Table 8-12 lists the avail- able salts and their associated calcium contents.
Contraindications
Contraindications for administration of exogenous calcium include hypercalcemia, ventricular fibrillation of the heart, and known allergy to a specific calcium drug product.
Adverse Effects
Although adverse effects and toxicity are rare, hyper- calcemia can occur. Symptoms include anorexia, nausea, vomiting, and constipation. In addition, when calcium salts are administered by intramuscular or subcuta- neous injection, mild to severe local reactions may occur,
including burning, necrosis and sloughing of tissue, cel- lulitis, and soft tissue calcification. Venous irritation may occur with intravenous administration. Other adverse effects associated with both oral and parenteral use of calcium salts are listed in Table 8-13.
Toxicity and Management of Overdose
Chronic and excessive calcium intake can result in severe hypercalcemia, which can cause heart irregularities, delir- ium, and coma. Management of acute hypercalcemia may require hemodialysis, whereas milder cases will respond to discontinuation of calcium intake.
Interactions
Calcium salts will chelate (bind) with tetracyclines to pro- duce an insoluble complex. If hypercalcemia is present in patients taking digitalis preparations, serious cardiac dysrhythmias can occur.
TABLE
8-11
Calcium Deficiency: Causes and Disorders
Cause Disorder
Hypoparathyroidism Muscle cramps Inadequate intake Infantile rickets Insufficient vitamin D Adult osteomalacia Malabsorption syndrome Osteoporosis
TABLE
8-12
Calcium Salts: Calcium Content
Calcium Salt Calcium Content (per gram)
Phosphate tribasic 400 mg (5.8 mmol)
Carbonate 400 mg (10 mmol)
Phosphate dibasic anhydrous 290 mg (7.3 mmol)
Chloride 270 mg (6.8 mmol)
Acetate 253 mg (6.3 mmol)
Phosphate dibasic dihydrate 230 mg (5.8 mmol)
Citrate 210 mg (5.3 mmol)
Lactate 130 mg (3.3 mmol)
Gluconate 90 mg (2.3 mmol) Glucoheptonate 82 mg (2.1 mmol)
TABLE
8-13
Calcium Salts: Adverse Effects
Body System Adverse Effects
Cardiovascular Gastrointestinal
Hemorrhage, rebound hypertension Constipation, obstruction, nausea,
vomiting, flatulence
Genitourinary Renal dysfunction, renal stones, renal failure
Metabolic Hypercalcemia, metabolic alkalosis
calcium
Calcium salts are minerals that are used primarily in the treatment or prevention of calcium depletion in patients in whom dietary measures are inadequate. Many calcium salts are available, all with a different content of elemental calcium per gram of salt. Calcium is available in both oral and parenteral (injectable) forms. There are numerous
dosages and names of calcium preparations. Consult manufacturer’s instructions for recommended dosages.
The pharmacokinetics of calcium are highly variable and depend on individual patient physiology and the characteristics of the specific drug product used. Calcium is pregnancy category C.
126
PART ONE Pharmacology Basicsadenosine triphosphate [ATP]) responsible for cellular energy transfer. It is also necessary for the development and maintenance of the skeletal system and teeth. The skeletal bones contain up to 85% of the phosphorus con- tent of the body. In addition, phosphorus is required for the proper utilization of many B-complex vitamins, and it is an essential component of physiological buffering systems.
Indications
Phosphorus is used to treat deficiency states and as a dietary supplement in many multivitamin formulations.
Contraindications
Contraindications to phosphorus or phosphate adminis- tration include hyperphosphatemia and hypocalcemia.
P H O S P H O R U S
Phosphorus is widely distributed in foods, thus a dietary deficiency is rare. Deficiency states are usually nondiet- ary and are primarily due to malabsorption, extensive diarrhea or vomiting, hyperthyroidism, hepatic disease, or long-term use of aluminum or calcium antacids.
Mechanism of Action and Drug Effects
Phosphorus in the form of the phosphate group or anion (PO4−3) is a required precursor for the synthesis of essential body chemicals. In addition, the mineral is an important building block for body structures. Phosphorus is required as a structural unit for the synthesis of nucleic acid and the adenosine phosphate compounds (adenosine mono- phosphate [AMP], adenosine diphosphate [ADP], and
M A G N E S I U M
Magnesium is one of the principal cations present in the intracellular fluid. It is an essential part of many enzyme systems associated with energy metabolism. Magnesium deficiency (hypomagnesemia) is usually caused by malabsorption, especially in the presence of high calcium intake; alcoholism; long-term intravenous feeding; diuretics; and metabolic disorders, including hyperthyroidism and diabetic ketoacidosis. Symptoms associated with hypomagnesemia include cardiovascu- lar disturbances, neuromuscular impairment, and men- tal health disorders. Dietary intake from vegetables and other foods will usually prevent magnesium deficiency. However, magnesium is required in greater amounts in individuals with diets high in protein-rich foods, cal- cium, and phosphorus.
Mechanism of Action and Drug Effects
The precise action mechanism for magnesium has not been fully determined. Magnesium is a known cofac- tor for many enzyme systems. It is required for muscle contraction and nerve physiology. Magnesium produces an anticonvulsant effect by inhibiting neuromuscular transmission for selected convulsive states.
Indications
Magnesium is used to treat magnesium deficiency and as a nutritional supplement in total parenteral nutri- tion (TPN) and multivitamin preparations. It is used
as an anticonvulsant in magnesium deficiency–induced seizures; for complications of pregnancy, including pre- eclampsia and eclampsia; as a tocolytic drug for inhib- ition of uterine contractions in premature labour; in acute nephropathy in children; for cardiac dysrhythmias; and for short-term treatment of constipation.
Contraindications
Contraindications to magnesium administration include known drug product allergy, heart block, renal failure, adrenal gland failure (Addison’s disease), and hepatitis.
Adverse Effects
Adverse effects of magnesium are due to hypermagnesia, which results in tendon reflex loss, difficult bowel move- ments, CNS depression, respiratory distress and heart block, and hypothermia.
Toxicity and Management of Overdose
Toxic effects are extensions of symptoms caused by hypermagnesemia, a major cause of which is the long- term use of magnesium products (especially antacids in patients with renal dysfunction). Severe hyperma- gnesemia is treated with a calcium salt administered intravenously in doses up to 10 mmol. The diuretic furo- semide (Lasix) may also be prescribed.
Interactions
The use of magnesium with neuromuscular blocking agents and CNS depressants produces additive effects.
magnesium
Magnesium is a mineral that has a variety of dosage forms and uses. It is an essential part of many enzyme systems. When absent or diminished in the body, cardio- vascular, neuromuscular, and mental health disorders
can occur. Magnesium sulfate is the most common form of magnesium used as a mineral replacement. It is preg- nancy category B.
Vitamins and Minerals CHAPTER 8
127
patient’s prothrombin time, international normalized ratio (INR), and platelet counts should be documented. Assessment of the skin for bruises, petechiae, and ery- thema should be completed as well as assessment of the gums for gingival bleeding. Urine and stool should also be assessed for bleeding prior to the use of this drug. Vital signs with attention to blood pressure and pulse rate should be noted. If intravenous (IV) dosage forms are used, it is important to assess baseline skin colour, temperature, and vital signs because of the asso- ciated risk for facial flushing, chest pain, weak pulse rate, profuse diaphoresis, and hypotension with pos- sible progression to shock and cardiac arrest. It is also important to remember that the fat-soluble vitamins are all stored in the body tissue when excessive quantities are consumed and may become toxic if taken in large doses; baseline values of vitamins A, D, E, and K should always be known prior to beginning any ordered or rec- ommended therapy.
Vitamin B1 (thiamine) hypersensitivity may cause skin rash and wheezing; therefore, presence of any allergic reactions to vitamin B compounds needs to be documented. Because it is rare that only one vitamin B1 deficiency occurs, deficiencies of all forms of vitamin B must be ruled out before treatment. Baseline assess- ments of vital signs, mental status, and urinary thiamine levels may also be ordered. When dietary intake is inad- equate, little or no thiamine is excreted in urine. When the diet contains an excess of the minimal requirement, the excess is excreted in urine as intact thiamine or as pyrimidine. Vitamin C is usually well tolerated; how- ever, assessment should include a history of nutritional deficits or problems with dietary intake, with notation of any allergies.
With trace elements, a baseline assessment should include contraindications, cautions, and drug inter- actions, as well as assessment of nutritional status and nutrition-related laboratory studies (Hgb, Hct, RBC, and
NURSING PROCESS
Assessment
Before administering vitamins, the nurse needs to assess the patient for nutritional disorders through a survey of laboratory tests such as Hgb, hematocrit (Hct), WBC and RBC counts, and serum albumin and protein levels. The patient’s dietary intake, dietary patterns, menu planning, grocery shopping, food and meal practices and habits, and ethnocultural influences should be assessed prior to giving any supplemental therapy. Contraindications, cautions, and drug interactions should also be noted.
For vitamin A deficiencies, a baseline assessment of the patient’s vision, including night vision, and exam- ination of the skin and mucous membranes should be completed and documented. Serum vitamin A levels less than 0.7 mcmol/L (adults) indicates a deficiency.
Patients who are deficient in vitamin D should have a baseline assessment of skeletal formation with attention to any deformities. Serum calcium levels should also be drawn as ordered. During the assessment phase for vita-