Respiratory%20Pharmacology

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Respiratory Pharmacology

• RC 195
• Dan Farrell

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Goal of Respiratory CareAirway Maintenance
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Two ways to name a drug Brand (Trade) name and
Generic Name
Always know a drug by both names!
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Respiratory Pharmacology Calculations
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Definitions

• Solute material to be dissolved
• Usually the actual drug
• Solvent the dissolving or diluting medium
• Almost always is water!

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Handy Conversions

• 1 ml 1 cc
• 1 gm 1000mg
• 1 gm H2O 1 ml H2O

• 1 lbs 454 gms
• 1 kg 2.2 lbs

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3 Ways to Express Drug Strength
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X mg/ml

• Tells how many milligrams of drug (solute) are in
  each ml of solution (solvent)
• 10 mg/ml 10 milligrams of drug in each ml of
  solution
• Best form to use for most calculations!

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Solution

• X grams of solute (drug) in each 100 ml of
  solvent (solution)
• 1 solution 1 gram of solute (drug) in each 100
  ml of solvent (solution)
• Is also the same strength as 10 mg/ml since 1
  1gm/100ml 1000mg/100 ml 10 mg/ml

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Dilution Ratio

• 1 gram solute (drug) per X grams (or ml) of
  solvent (solution)
• 1100 1 grams of drug (solute) per 100 grams of
  solvent (or ml of solution)
• 1100 1000mg/100 ml 10 mg/ml

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10 mg/ml, 1 and 1100 are all the same strength
just expressed 3 different ways
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Conversions mg/ml to solution

• Move decimal point 1 place to the left!
• 10 mg/ml
• 1
• 75 mg/ml
• 7.5

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Conversions solution to mg/ml

• Move decimal point 1 place to the right!
• 2
• 20 mg/ml
• .5
• 5mg/ml
• 7.5
• 75 mg/ml

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Conversions Dilution Ratio to Solution

• Convert to mg/ml and then move decimal point 1
  place to the left!
• 1 1000 1 gram per 1000 grams 1000mg/1000 ml
  (why?)
• 1 mg/ml .1

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Conversions mg/ml or solution to a dilution
ratio

• If in mg/ml, first change to solution, then
  express the solution by its definition and then
  divide it out
• Crystal clear, isnt it!?!?!?
• 20 mg/ml 2 solution
• By definition, a 2 solution is 2 grams of
  solute (drug) in every 100 grams of solvent
  (solution) or 2 100
• By dividing it out, you get the true dilution
  ratio
• 2100 is 150 dilution ratio

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Calculations

• To determine how many mg of drug are in X ml of
  solution, or to determine how many ml of solution
  contain Xmg of drug, use
• mg/ml (available) mg/ml (desired)
• where mg/ml (available) is the strength of the
  drug. Solve for the desired variable on the
  right side (desired) side of the equation

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Calculation ExampleHow many ml of 1
Isoetharine (Bronkosol) are needed to give the
patient 2.5 mg of drug?

• Convert 1 to mg/ml and use the equation
• mg/ml (available) mg/ml (desired)
• 1 10 mg/ml, so
• 10 mg/ml 2.5 mg/X ml
• Using algebra, solve for X
• X .25 ml

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Thus, to give a patient 2.5 mg of 1 Isoetharine
(Bronkosol), you would need to administer .25 ml
of 1 Isoetharine (Bronkosol)
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Calculation Example How much drug does a patient
get if you administer .5 ml of .5 Albuterol
(Proventil)?

• Convert .5 to mg/ml and use the equation
• mg/ml (available) mg/ml (desired)
• .5 5 mg/ml, so
• 5 mg/ml X mg/.5 ml
• Use algebra and solve for X
• X 2.5 mg

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Thus, if a patient receives .5 ml of .5
Albuterol (Proventil), he receives 2.5 mg of
Albuterol (Proventil)!
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Calculations Diluting a Solution

• Use formula, V¹C¹ V²C², where
• V¹ Volume of desired solution
• C¹ Concentration (strength) of desired
• solution
• V² Volume of available solution to be
• drawn up and diluted
• C² Concentration (strength) of
  available
• solution

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Calculation Example

• Give 15 ml of 2.5 Sodium Bicarb. You have 20 ml
  of 7.5 available.
• Dont be misled by the amount of solution
  available! Its not part of the equation!
• V¹ 15 ml
• C¹ 2.5
• V² X (what you are solving for how much of
  the available solution you are going to use)
• C² 7.5

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V¹C¹ V²C²

• 15 ml (2.5) X ml (7.5)
• 15ml (2.5)/7.5 X ml
• Xml 5 ml V²
• Take 5 ml of the 7.5 solution and add enough
  water to end up with 15 ml of solution
• Adding 10 ml of water to 5 ml of 7.5 solution
  will yield 15 ml of 2.5 solution!

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Calculation Example

• Give 8 ml of 50 ETOH. You have 12 ml of 80
  ETOH available.
• V¹ 8 ml
• C¹ 50
• V² X (the amount of 80 ETOH to be used for
  dilution)
• C² 80

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V¹C¹ V²C²

• 8 ml (50) X ml (80)
• 8 ml (50)/80 X ml
• X ml 5 ml V²
• Take 5 ml of 80 ETOH and add enough water to end
  up with 8 ml of solution
• Adding 3 ml of water to 5 ml of 80 ETOH will
  yield 8 ml of 50 ETOH!

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Lets get the hell out of here and take a break!!