Transcript Respiratory Pharmacology

Respiratory Pharmacology
RC 195
Dan Farrell
Goal of Respiratory Care:
Airway Maintenance
Two ways to name a drug: Brand
(Trade) name and Generic Name
Always know a
drug by both
names!
Respiratory Pharmacology
Calculations
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
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1 ml = 1 cc
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1 lbs = 454 gms
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1 gm = 1000mg
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1 kg = 2.2 lbs
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1 gm H2O = 1 ml H2O
3 Ways to Express Drug Strength
“X” mg/ml
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Tells how many milligrams of drug (solute)
are in each ml of solution (solvent)
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10 mg/ml = 10 milligrams of drug in each
ml of solution
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Best form to use for most calculations!
% Solution
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“X” grams of solute (drug) in each 100 ml
of solvent (solution)
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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
Dilution Ratio
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1 gram solute (drug) per “X” grams (or ml)
of solvent (solution)
 1:100 = 1 grams of drug (solute) per 100
grams of solvent (or ml of solution)
 1:100 = 1000mg/100 ml = 10 mg/ml
10 mg/ml, 1% and 1:100 are all
the same strength just expressed
3 different ways
Conversions: mg/ml to %
solution
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Move decimal point 1 place to the left!
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10 mg/ml =
1%
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75 mg/ml =
7.5%
Conversions: % solution to
mg/ml
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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, isn’t 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:
2:100 is 1:50 dilution ratio
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Calculations
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To determine how many mg of drug are in “X” ml
of solution, or to determine how many ml of
solution contain “X”mg 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
Calculation Example:
How 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)
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)!
Calculations: Diluting a Solution
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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
Calculation Example
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Give 15 ml of 2.5% Sodium Bicarb. You have 20
ml of 7.5% available.
Don’t be misled by the amount of solution
available! It’s 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%
V¹C¹ = V²C²
15 ml (2.5%) = “X” ml (7.5%)
 15ml (2.5%)/7.5% = “X” ml
 “X”ml = 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%

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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Let’s get the hell out of here and take a break!!