Aerosolized Medications

1
Aerosolized Medications

• By Jim Clarke

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Review of Terms Principles

• Stability - tendency for a drug to remain in
  suspension
• Penetration - describes how deeply aerosols reach
  into the lung

3
Review of Terms Principles

• Deposition - process of particles settling onto
  lung tissue
• Mass Median Diameter (MMD) - the particle size in
  which 50 of particles are bigger or smaller

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Particle Size Lung Deposition

• Particles gt10 - 15 microns land in mouth nose

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Particle Size Lung Deposition

• Particles 5 to 10 microns land in upper airways
• Particles 1 to 5 microns reach lower airways
  alveoli
• These particles are called the respirable
  fraction

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Particle Size Therapeutic Effect

• Particles gt 10 microns ideal for treatment of
  nasopharyngeal or oropharyngeal regions
• Particles 5 to 10 microns for conditions
  affecting the larger more central airways

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Particle Size Therapeutic Effect

• Particles 2 - 5 microns for conditions affecting
  mid-size smaller airways
• Administration of bronchodilators
• Particles .5 to 2 microns for deposition in the
  alveolar regions

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Mechanisms of Deposition

• Inertial Impaction
• Gravitational Settling
• Diffusion
• Effect of Temperature Humidity
• Pattern of Inhalation

9
Aerosol Delivery Devices

• Metered Dose Inhaler - MDI
• Dry Powdered Inhaler - DPI
• Small Volume Nebulizer - SVN
• Ultrasonic Nebulizer - USN

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How Flowrate Used During SVN Therapy Affects
Nebulization Time
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Effect of Flowrate on MMAD
12
How Devices Differ In Terms of Deposition
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Other Ways to Administer Aerosols

• Via IPPB using inline small volume nebulizer
  present in the circuit
• SVN in-line with a ventilator circuit
• MDIs can also be given inline with a ventilator
  circuit with the use of a spacer inserted into
  the circuit

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Issues to Consider When Giving Inline Aerosols

• If an artificial nose is being used in the
  circuit, it must be removed during the Tx
• A filter may need to be placed on the expiratory
  side of the circuit to collect exhaled mist

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Health of the Lung Affects Deposition of Aerosols

• Normal individuals have uniform and widespread
  aerosol deposition
• Smokers have deposition that tend to miss small
  airways
• Persons with COPD have poor peripheral deposition

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Break Time!!

• Ten Minutes Please!!

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Calculating Drug Doses
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Metric Review

• Volume Measurements
• Base unit is the liter
• 1 Deciliter .1 liter
• 1 Centiliter .01 liter
• 1 milliliter .001 liter
• 1 microliter - .000001 liter

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Metric Review

• Weight Measurements
• Base unit is the gram
• 1 Decigram .1 gram
• 1 Centigram .01 gram
• 1 milligram .001 gram
• 1 microgram - .000001 gram

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Important Equivalences

• 1 cc 1 ml
• 1 ml 16 drops (gtts)
• Therefore
• 4 drops 1/4 cc
• 8 drops 1/2 cc
• 12 drops 3/4 cc

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Calculating Doses of Drugs

• Steps
• 1. Write down what you know
• 2. Determine what is the unknown
• 3. Let the unknown equal x
• 4. Solve for x

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Example

• You are asked to give 50 milligrams of a drug
  that is available in a solution which is 7.5
  mg/cc. How many ccs would you give?
• Solution available 7.5 mg/cc
• Desired amount to give 50 mg
• 50 mg 7.5 mg x 1 cc
  
  
• x 6.7 cc

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Dosage According to Body Weight

• Drugs may be given based upon how much the
  patient weighs
• 15 mg/kg of body weight

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Example

• You are asked to give an antibiotic solution via
  aerosol in the following dosage schedule - 25
  mg/kg of body weight. How much would you give
  if the patient weighed 110 lbs? First of
  all convert 110 lbs. to kg - 110 lbs x 1 kg
  50 kg
  2.2
  lbs

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Example Continued

• Multiply schedule amount times the body weight in
  kg. 25 mg x 50 kg 1250 mg
  kg
• Easy!!!

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Calculating Doses From Percentage Strength
Solutions

• Terms
• Solute - material to be dissolved
• Solvent - material that dilutes (holds) the
  solute
• Strength is expressed as a percentage comparison
  of the solute divided by the solvent
• Weight to Volume (grams / ml)
• Solutions by solute to solvent ratio
• 1100 or 11000

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Solving Percentage- Strength Problems

• Solution strength is based upon the following
  principle
• 1 gram of a solute dissolved in 100 ml of solvent
  is a 1 solution. Therefore if 1
  gram 1000 mg then 1000 mg 10
  mg/ml 100 ml so then we can say
  that 1 10 mg/ml

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Common Percentage Strengths

• Percentage Strength mg/ml 20 200
  mg/ml 10 100 mg/ml 5 50
  mg/ml 1 10 mg/ml 0.5 5
  mg/ml 0.1 1 mg/ml 0.01 0.1 mg/ml

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Solving Percentage- Strength Problems in
Milligrams per Milliliter

• To express strength as a , divide the amount of
  the drug (expressed in mg/ml) by the volume of
  the solution it is dissolved in
• 50 mg is dissolved in 250 ml of normal saline
  therefore 50 mg x 100 20
  solution 250 ml

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Solving Percentage- Strength Problems in
Milligrams per Milliliter

• To determine how much drug (in mg/ml) is in a
  solution
• Take the strength and multiply it by 10
• For example 10 drug is actually
  100mg/ml since 10 x 10 100 mg/ml

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Solving Percentage- Strength Problems in
Milligrams per Milliliter

• To convert from a known ratio of mg/ml to a
  strength - divide the ratio by 10
• For example
• A solution contains 200 mg/ml. How is that
  expressed in strength? 200 mg/ml
  20 10

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Diluting Drugs

• To make a solution more dilute (weaker) setup the
  following CiVi
  CfCf where C
  concentration V volume i initial f
  final

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Dilution Continued

• Solve for Cf or Vf depending on what the question
  is asking. For example
• You are asked to give a treatment with Mucomyst
  that is available as a 10 ml bottle of 20
  solution. However the doctor wants the Mucomyst
  to be given as a 10 solution. How much diluent
  (saline) must be added to the original vial to
  create a 10 solution?

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Dilution Example Continued

• Setup the problem by assigning variables
• Ci 20 Vi 10 ml
• Cf 10 Vf ?
• Solve for the unknown Vf Vf Ci x Cf 20 x
  10 20 ml Vi 10
• Remember we still must subtract the initial
  volume from the final volume to arrive at the
  volume of saline to add 20ml - 10 ml 10 ml

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HEART Nebulizer Problems

• To solve these problems
• 1. Determine what is the prescribed dose in
  mg/hr
• 2. Divide the prescribed dose by the available
  solution strength to determine how much drug
  to add to the nebulizer
• 3. Subtract the answer from 2 from the
  output of the unit given by the manufacturer to
  to determine the amount of saline to add

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Another Way to Solve HEART Problems

• Refer to the HEART nebulizer handout
• Note you still need to be able to demonstrate
  proficiency with the method from the previous
  slide however!
• The End (Arent you glad!)