Pharmaceutical Injections Quiz

Inorganic Pharmaceutical Chemistry - Replacement Therapy

• Replacement therapy aims to restore the volume and composition of body fluids to normal levels.
• Volume contraction is life-threatening due to impaired circulation, decreased blood volume, and compromised microcirculation.
• When volume depletion is life-threatening, prompt infusion of isotonic sodium chloride solutions is necessary.
• In severe cases, intravenous therapy at 100 mL per minute for the first 1000 mL may be needed for treatment of conditions like cholera.

Sodium Replacement

• Sodium Chloride (NaCl; MW 58.44) occurs as colorless cubic crystals or white crystalline powder, having a saline taste.
• It's freely soluble in water, more soluble in boiling water, soluble in glycerin, and slightly soluble in alcohol.
• Sodium chloride is used in replacement therapy, isotonic solution production, and as a flavor enhancer.

Uses of Isotonic, Hypotonic, and Hypertonic Solutions

• Isotonic solutions are used as wet dressings and for irrigating body cavities or tissues.
• Hypotonic solutions are used for maintenance therapy when patients can't take fluids or nutrients orally for a few days.
• Hypertonic injections are used for severe sodium loss and should be administered slowly, in small volumes (200–400 mL).

Official Preparations of Sodium Replacement

• Sodium Chloride Injection, solution, and tablets.
• Bacteriostatic sodium chloride injection.
• Dextrose and sodium chloride injection and tablets.
• Mannitol and sodium chloride injection.
• Fructose and sodium chloride injection.
• Ringer's injection.
• Lactate Ringer's injection.

Sodium Chloride Injection

• A sterile isotonic solution of sodium chloride in water for injection.
• Contains not less than 0.85% and not more than 0.95% w/v of sodium chloride.
• Contains no antimicrobial agents.
• A clear, colorless solution with a pH between 4.5–7.0.

Sodium Chloride Hypertonic Injection

• A sterile solution of sodium chloride in water for injection.
• Contains not less than 1.52% and not more than 1.68% w/v of sodium chloride.
• Contains no antimicrobial agents.
• A clear, colorless solution with a pH between 5.0–7.5.

Compound Sodium Chloride Injection (Ringer Injection)

• It contains:
  • Not less than 0.82% and not more than 0.9% w/v of sodium chloride.
  • Not less than 0.0285% and not more than 0.0315% w/v of potassium chloride.
  • Not less than 0.03% and not more than 0.036% w/v of calcium chloride in water for injection.
• Contains no antimicrobial agents.
• A clear, colorless solution with a pH between 5–7.5.

Sodium Chloride and Dextrose Injection

• A sterile solution of sodium chloride and dextrose in water for injection.
• A clear, colorless, or faintly straw-colored solution with a pH between 3.5–6.5.
• Contains 0.9% sodium chloride and 5% dextrose.

Potassium Replacement

• Potassium Chloride (KCl; M.Wt. 74.56) occurs as colorless, elongated prismatic or cubical crystals, or as white granular powder.
• Odorless, has a saline taste, and is stable in air.
• Freely soluble in water and even more soluble in boiling water, with a neutral solution to litmus. Insoluble in alcohol.
• Uses: Oral potassium replacement (solution needs dilution), familial periodic paralysis, Meniere's syndrome, digitalis intoxication antidote. Can be used as an adjunct in myasthenia gravis treatment.

Contraindications for Potassium Replacement

• Impaired renal function with oliguria (diminished urine output).
• Acute dehydration.
• Hyperpotassemic conditions like myotonia congenita, adynamia episodica hereditaria (periodic weakness or paralysis of skeletal muscle).
• Potassium-sparing drugs.

Official Preparations of Potassium Replacement

• Potassium chloride injection and tablets.
• Ringer's injection.
• Lactate Ringer's injection.
• Lactate potassium saline injection.
• Potassium gluconate elixir and tablets.

Calcium Replacement

• Calcium Chloride (CaCl₂·2H₂O; M.Wt. 147.02) occurs as white, hard, odorless fragments or granules.
• Freely soluble in water, alcohol, and boiling alcohol; very soluble in boiling water.
• Irritating to veins, so inject slowly.
• Used as a calcium source in electrolyte replacement and maintenance solutions.

Official Preparations of Calcium Replacement

• Calcium chloride (in Ringer's and Lactate Ringer's injection).
• Calcium gluconate injection and tablets.
• Calcium lactate tablets.
• Dibasic calcium phosphate.
• Tribasic calcium phosphate.

Parenteral Magnesium Administration

• Magnesium Sulfate (MgSO₄·7H₂O; M.Wt. 246.47).
• Used as a central nervous system depressant for treating eclampsia (convulsions and coma) and magnesium deficiency in alcoholics.
• Overtreatment can cause respiratory paralysis and cardiac depression.
• IV injection of calcium salts is used to counteract magnesium intoxication. Should not be administered to patients with renal insufficiency.
• Used as an anticonvulsant and cathartic.

Physiological Acid-Base Balance

• pH disturbances in the body are clinically significant.
• Acidemia and alkalemia refer to abnormal decreases/increases in blood pH, respectively.
• Acidosis and alkalosis are clinical states that could cause acidemia or alkalemia.
• Extent of pH change depends on compensation, which varies in different clinical cases.
• Acids, such as carbonic (from CO2) and lactic (from anaerobic metabolism), are constantly produced during metabolism.

Buffer Systems

• The body uses buffer systems to maintain a narrow pH range (7.38–7.42).
• Bicarbonate/carbonic acid (HCO₃⁻/H₂CO₃) is present in plasma and kidneys.
• Monohydrogen/dihydrogen phosphate (HPO₄²⁻/H₂PO₄) is found in cells and kidneys.
• Red blood cells (RBCs) have a hemoglobin buffer system which is highly effective in buffering carbonic acid produced during metabolism.
• During metabolic processes, CO2 diffuses from cells and into plasma, reacting with water to form carbonic acid. This increased carbonic acid is buffered by plasma proteins. Many CO2 enters erythrocytes, where it forms H2CO3, with the help of carbonic anhydrase, and combines with Hb.

Kidney's Role in Acid-Base Balance

• Sodium salts of mineral or organic acids are removed from the plasma through glomerular filtration.
• Tubular fluid reacts with carbonic acid (formed by carbonic anhydrase) in the tubular cells, and this reaction is sometimes called Na⁺–H⁺ exchange.
• NaHCO₃ returns to the plasma (removed in lungs as CO2), and the protons enter the tubular fluid, forming acids from the original anion sodium salts, such as H₂PO₄⁻, lactate, etc.

Types and Causes of Acidosis and Alkalosis

• Metabolic acidosis: Primary bicarbonate ion deficit and causes include diabetic acidosis, renal failure, diarrhea. Compensatory mechanisms include hyperventilation and increased acid excretion.
• Respiratory acidosis: Excess carbonic acid and causes include cardiac disease, lung conditions, drowning. Compensatory mechanisms include increased CO2 excretion, increased acid excretion, and increased NH₃ formation.
• Metabolic alkalosis: Excess HCO₃⁻ and causes include administration of excessive alkali, vomiting, and potassium ion. Compensatory mechanisms include CO₂ retention, decreased Na⁺–H⁺ exchange, decreased NH₃ formation, and HCO₃⁻ reabsorption.
• Respiratory alkalosis: Primary H₂CO₃ deficit and causes include fever, hysteria, anoxia, and salicylate poisoning. Compensatory mechanisms include CO₂ retention, decreased Na⁺–H⁺ exchange, decreased NH₃ formation, and HCO₃⁻ reabsorption.

Electrolytes used in Acid-Base Balance

• Sodium acetate is metabolized to CO₂ and then to bicarbonate, used as an effective buffer in metabolic acidosis. Effective in treating metabolic acidosis from cholera and uremia.
• Potassium acetate: Alkalinity increases as the solution sits, is stored in closed containers. It's soluble in water but insoluble in alcohol.
• Sodium bicarbonate is an alkalizer used to combat gastric hyperacidity and systemic acidosis, often available as an injection or tablet form.
• Potassium bicarbonate is a colorless, transparent, monoclinic prism, or a white granular powder; odorless and stable in air.
• Sodium biphosphate is a urinary acidifier.
• Sodium citrate is used as an anticoagulant, chelating serum calcium, and as a buffer. It has a diuretic effect due to increased body salt concentration. Potentially useful in cases of chronic acidosis.
• Potassium citrate is a white granular powder, odorless and cooling, freely soluble in water and almost insoluble in alcohol.

Electrolyte Combination Therapy

• In short-term therapy (e.g., post-surgery), standard glucose and saline infusions may suffice, but severe or protracted electrolyte deficits may require solutions containing additional electrolytes.
• Combinations are usually not feasible from the standpoint of patient-specific needs or cost/sterility.
• Combination products can be categorized into fluid maintenance and electrolyte replacement solutions.
• Maintenance therapy is intended to supply normal water and electrolyte requirements intravenously for patients unable to take it orally, minimizing metabolites associated with starvation. Solutions contain at least 5% dextrose and electrolytes like Na, K, Cl, HCO3 (or equivalent amounts of lactate or acetate), Mg, and P for overall maintenance.

Replacement Therapy Situations

• Prolonged fever.
• Severe vomiting.
• Diarrhea.
• Rapid initial replacement solutions have electrolyte concentrations resembling extracellular fluid.

Official Electrolyte Infusion Combinations

• Ringer's injection contains potassium chloride, sodium chloride, and calcium chloride dihydrate, equivalent to Na, K, Ca, and Cl.
• Lactated Ringer's injection contains sodium chloride, sodium lactate (equivalent), potassium chloride, and calcium chloride dihydrate; usually available as injections.

Oral Electrolyte Solutions

• Oral electrolyte solutions are available, such as Lytren or Pedialyte, for electrolyte and fluid maintenance when oral intake isn't possible or insufficient (e.g., diarrhea).