Metric System, Dosage
Calculations, & Autonomic
Nervous System
MODULE B
Objectives
At the end of the module you will:
• Given a prefix, state the related power of 10.
• Define solute, solvent, and solution.
• Given two of the following three parameters,
solve for the third: Percent of Solution,
Mass of drug (in grams or milligrams),
Volume of drug (in mL or L).
• Calculate the body surface area, given a
height, weight, and the Dubois Nomogram.
Objectives
At the end of the module you will:
•
Describe the divisions of the central and peripheral
nervous systems.
•
Define key terms relative to pharmacology of the
autonomic nervous system.
•
Describe the anatomy, neurotransmitters, and
receptors of the autonomic nervous system.
•
State four classifications of autonomic nervous
system drugs on the basis of how and where they
work.
•
Relate the pharmacology of the autonomic nervous
system to the "specific chapters" and drug
classifications that are relevant.
Metric System Prefixes and
Abbreviations
Unit Conversions
If a patient voids 3.2 liters of urine in a day, what is
the average urine output in mL/hr?
3.2 L x 1000 mL
= 3,200 mL
1.0 L
3,200 mL x 1 day = 133 mL
day
24 hrs
hr
Definitions
• Solute: Liquid or solid dissolved in a
liquid.
• Solvent: The liquid that dissolves the
solute.
• Solution: A chemical and physical
homogenous mixture of two or more
substances.
Percentage and Ratio Solutions
•Percentage Solutions
•A 20% solution means that there are 20
grams of solute for every 100 mL of solution.
•Example
20 g of solute
1 g of solute
20% 
100 mL of solution

5 mL of solution
•Ratio Solution
•A 1:200 solution means that there is 1 mg of
solute in 200 mL of solution
•Example
1 mg of solute
1 : 200 
200 mL of solution
Dosage Calculation
How many mg of active ingredient are
there in 4.0 mL of 1:200 albuterol?
1 mL a l buterol
1
1 : 200 

 0.5% sol uti on
200 mL sol uti on 200
0.5 g
500 mg 5 mg
0.5% 


100 mL 100 mL 1 mL
Set up proporti on
s:
5 mg  mg

1 mL
4 mL
5 mg  4 mL   mg  1 mL
20 mg  mL   mg  20 mg
1 mL
Easy Way
# mL x # % x 10 = # mg
1 mL a lbuterol
1
1 : 200 

 0.5% solution
200 mL solution 200
# mL  # %  10  # mg
4 mL  0.5  10  20 mg
•Dubois Nomogram
•Height = 72 inches
•Weight = 190 pounds
•What is the BSA?
Nervous System
CNS
PNS
Nervous System Divisions
AFFERENT
EFFERENT
Somatic Nervous System
• Control of skeletal muscles.
• Only one junction.
• Acetylcholine is the neurotransmitter.
Autonomic Nervous System
• Two Divisions
• Sympathetic
• Alert system for stressful situations
• “Fight or Flight”
• http://wps.prenhall.com/chet_colbert_intcardpha
_1/0,5136,93290-,00.html
• Parasympathetic
• Maintain homeostasis
• “Rest and Digest”
Nervous System Conduction
• Upon stimulation, electrical impulse carries
the signal along the nerve fiber or axon.
• The signal then comes to a small junction or
synapse, beyond which is a muscle, gland or
another nerve.
• The connection across the synapse is
accomplished by a chemical
neurotransmitter.
• Two neurotransmitters:
• Acetylcholine (ACH)
• Norepinephrine (NE)
BRAIN
C
T
VISCERA
SPINAL
COLUMN
L
S
C
PARASYMPATHETIC
PREGANGLIONIC
SYMPATHETIC
PREGANGLIONIC
PARASYMPATHETIC
POSTGANGLIONIC
SYMPATHETIC
POSTGANGLIONIC
NICOTINIC RECEPTOR SITE WITH ACH
ADRENERGIC RECEPTOR SITE WITH NE
MUSCARINIC RECEPTOR SITE WITH ACH
Autonomic Nervous System
• Two types of junctions are present.
• Pre-ganglionic
• Conducts impulse from the CNS to the peripheral
ganglion.
• Post-ganglionic
• Transmits impulse from the ganglion to the neuroeffector
site (target).
• Both Sympathetic and Parasympathetic Nerve
fibers have both types.
• ACH at both Pre-Ganglionic.
• NE (E) at post-ganglionic of Sympathetic Nerve
• ACH at post-ganglionic of Parasympathetic Nerve
Receptors
• Specific receptors for each neurotransmitter.
• Acetylcholine is “attracted” to cholinergic sites
• Muscarinic – Smooth & Cardiac muscle, exocrine
• Nicotinic – Pre-Synaptic Junction
• Also located in Somatic Nervous System
• Norepinephrine (& Epinephrine) are “attracted” to
post-synaptic adrenergic sites
•



Smooth & Cardiac muscle, exocrine
a: Blood Vessel
b1: Heart
b2: Bronchi
Receptor Types - Adrenergic
• Adrenergic Receptors: Act through the
release of epinephrine or norepinephrine.
• Any drug that mimics the effects of epinephrine
(adrenaline) is termed an adrenergic or
sympathomimetic drug.
• EXAMPLE: Bronchodilator
• A drug that antagonizes the adrenergic receptor
site are called anti-adrenergics or sympatholytics.
• Second type of Adrenergic receptor is the
dopaminergic receptor found in renal tissue.
• Stimulation causes relaxation of renal arteries and
increased renal perfusion
Nerve Receptor Types Cholinergic
• Cholinergic Receptors: Act through the release
of acetylcholine.
• Any drug that mimics the effects of acetylcholine is
termed an cholinergic or parasympathomimetic drug.
EXAMPLE: Bronchoconstrictor
• Any drug that blocks the blocks cholinergic receptors
are called Anticholinergics or parasympatholytics.
• EXAMPLE: Beta-Blockers
Neurotransmitter Elimination
• After the nerve stimulation occurs, the
neurotransmitter is eliminated by one of the
following mechanisms:
• Norepinephrine & Epinephrine are either:
• Reabsorbed by the axon terminal that secreted it.
• Deactivated by the enzymes COMT or MAO.
• COMT: Catechol-O-Methyl-Transferase
• MAO: Monamine Oxidase
• Acetylcholine is deactivated by
actetylcholinesterase, also known as
cholinesterase.
• A desired effect can occur due to stimulation
of the desired neurotransmitter or inhibition of
the enzyme that breaks it down.