Compounds of Calcium

• The body contains about 2 per cent of calcium, 99 per cent of which is in the bones

  
• The cells and body fluid contain from 10-15 mg. per 100 g. (5-7 m Eq/L) of calcium

  
• Blood calcium


  Part is bound with protein and is non-diffusible, part is diffusible as undissociated phosphates, carbonates, and as ionic calcium
• The diffusible ionic calcium is only 3 to 4 mg. per 100 g.

  
• The cerebrospinal fluid contains only 6 mg. per 100 g. (3 mEq/L) of calcium
• The calcium in the blood and tissues and that in the skeleton are in equilibrium

  
• The medication of the parathyroids is necessary for the withdrawal of calcium from the skeleton
• The daily body requirement of calcium is about 450 mg
• Calcium requirements


  • Adults: 10 mg per kg of body weight per day
  • Pregnant and lactating women: Higher depletion, need increased intake
  • Growing children: 40 to 60 mg per kg per day
• Human milk contains 0.035 per cent of calcium, and a six months old baby consuming about one litre per day depletes the mother of about 0.4 g. of calcium
• Cow's milk contains 0.126 per cent of calcium, and a litre provides a full day's ration of calcium in a readily assimilable form
• Calcium gets absorbed from the upper intestinal tract, and is excreted through urine and faeces
• Acidic conditions in the upper intestine favour absorption of calcium, while alkaline conditions and higher fatty acid contents decrease absorption
• Calcium ions


  • Control nerve excitability, maintain integrity of skeletal muscles, maintain tone and contractility of heart, aid enzyme action, essential for blood clotting, decrease cellular permeability, take part in formation of tissues and bones

  
• Hypocalcemia (deficiency of ionised calcium in blood) can occur due to nutritional deficiencies, hypoparathyroidism, renal insufficiency, neonatal tetany, and large volumes of citrated blood transfusion
• Hypercalcemia (high concentration of calcium ions in blood) can occur due to hyperparathyroidism, hyperthyroidism, milk alkali syndrome, diuretic use, excess Vitamin D, and sarcoidosis
• Treatments for hypercalcemia


  • Prednisolone and some steroids
  • Indomethacin
  • Disodium edetate
  • Calcitonin and phosphates
• Calcium compounds are given in deficiency states or as dietary supplements, and are useful in immediate treatment of low calcium tetany
• Acute calcium deficiency increases neuromuscular excitability and causes tetany, while chronic deficiency leads to deformity of bones as in rickets
• Parathyroid increases blood calcium by drawing it from the bones, while hypothyroidism increases calcium retention and hyperthyroidism increases calcium excretion
• Vitamin D is essential for proper absorption of calcium, and both calcium and Vitamin D are needed to cure rickets and allied conditions
• Indications for calcium therapy

  • Calcium deficiency disorders and increased calcium demand
  • Haemorrhagic states caused by or accompanied by calcium deficiency
  • Nervous disorders responsive to sedative action of calcium
  • Allergic disorders and states of autonomic imbalance
  • Acute inflammatory and exudative disorders
  • Toxic states
• Calcium Acetate


  A white, hygroscopic powder that is slightly soluble in water and slightly alkaline in aqueous solution

  
• Calcium Acetate may be prepared by neutralising acetic acid solution with calcium carbonate or calcium hydroxide
• Calcium Acetate can be assayed by complexometric titration with disodium edetate using methyl thymol blue as indicator

  
• Calcium Acetate (B.P.)


  Formula: C4H6Ca04, Mol. wt.: 158.2, It is having not less than 98% but not more than 100.5% of C4H6Ca04, calculated with reference to the anhydrous substance

  
• Preparation of Calcium Acetate

  Neutralising acetic acid solution with suitable calcium salts like calcium carbonate or calcium hydroxide

  
• Calcium Acetate


  • It occurs as a white powder, It is almost colourless and hygroscopic in nature, It is soluble in water but slightly soluble in alcohol, Its aqueous solutions are slightly alkaline in nature

  
• Assay of Calcium Acetate


  Dissolved in water, buffered with diethylamine and titrated with 0.1 M disodium edetate using methyl thymol blue mixture as indicator

  
• Calcium Carbonate - Prepared Chalk

  Syn.: Creta Praeparata, It has been a native form of calcium carbonate that gets freed from most of its impurities by elutriation, It is having, when dried at 180°C for four hours, not less than 97% of CaC03

  
• Preparation of Prepared Chalk


  Suspending the powdered native chalk in cold water, permitting the heavier materials to subside and straining the milky aqueous suspension of the finer particles through a suitable cloth, The pasty mass gets transferred from the strainer to funnel, from which it gets dropped upon porous tiles
• Prepared Chalk


  • It is a white or greyish-white, It is odourless, tasteless, friable masses or powder, It may be distinguished from precipitated calcium carbonate by its dark and coarse appearance, when seen under a microscope
• Calcium Chloride Hydrated


  Formula: CaCl2.6H20, Mol. wt.: 219.1, It is having not less than 98.0% and not more than the equivalent of 102% CaCl2.6H20

  
• Preparation of Calcium Chloride Hydrated

  Obtained as a by-product in ammonia soda process for the manufacture of sodium carbonate, Obtained by the addition of pure calcium carbonate in slight excess to the hot dilute hydrochloric acid

  
• Calcium Chloride Hydrated


  • It occurs as white deliquescent odourless crystals or granules, having slight bitter taste, It is soluble in water and alcohol, It reacts with ammonia and combines with eight molecules of ammonia, It has cooling effect, An aqueous solution of the salt is acidic in nature
• Identification of Calcium Chloride Hydrated

  When heated in a dry test tube, it melts and expels water, Its reactions have been characteristic of calcium and chloride

  
• Assay of Calcium Chloride Hydrated

  Adjusted to desired pH using sodium hydroxide solution and titrated with disodium edetate solution using calcon mixture as indicator

  
• Calcium Gluconate


  Formula. C12H220 14Ca.H20, Mol. wt.: 418.4, It is having not less than 99.0% and not more than 103.0% of C12H220 14 Ca.H20

  
• Preparation of Calcium Gluconate

  Obtained either by the oxidation of glucose to gluconic acid in the presence of calcium carbonate or by first getting gluconic acid and then reacting with calcium carbonate

  
• Calcium Gluconate


  • It exists as odourless white crystalline granules or powder, It is tasteless, It is stable in air, but loses its water of crystallization with decomposition at 100°C, It is incompatible with oxidising agents and the solution of calcium gluconate gets precipitated by oxalate, borate etc.