Transcript masseychem.weebly.com

Antacids & Analgesics
By Cassidy Cole, Monica Rogoz and Megan Shaw
Antacids
❖ Weak bases
➢ neutralize excess acid
■ work by neutralizing hydrochloric acid
➢ often metal oxides/hydroxides, or
carbonates/hydrogencarbonates
■
react with the acid to produce a salt and water
(and carbon dioxide)
➢ combat acid indigestion, heartburn, and
Examples of Antacids
❖ Al(OH)3
➢ how does it work?
■ Al(OH)3 (s) + 3HCl (aq) → AlCl3 (aq) + 3H2O (l)
❖ Mg(OH)2
➢ how does it work?
■ Mg(OH)2 (s) + 2HCl (aq) → MgCl2(aq) + 2H2O (l)
❖ Many antacid formulations include both Mg and Al
➢ Mg is fast acting and Al provides long lasting relief
Examples of Antacids (cont.)
❖ NaHCO3
➢ how does it work?
■ NaHCO3(aq) + HCl (aq) → NaCl(aq) + H2O(l) + CO2(g)
❖ CaCO3
➢ how does it work?
■ CaCO3(s) +2HCl (aq) → CaCl2(aq) + H2O + CO2(g)
❖ Since CO2 can cause bloating and flatulence, antifoaming agents
(ie. dimethicone) are often added to the formulation
❖ To prevent heartburn, some antacids contain alginates which float
on on top of the contents of the stomach and form a barrier
between the stomach and the oesophagus
Acidity in the stomach
❖ The gastro-intestinal tract maintains specific pH
environments
➢ in order to control the activity of digestive enzymes
❖ The stomach generates pH values as low as 1-2
(hydrochloric acid)
➢ kills bacteria, provides optimum environment for
digestive enzymes
❖ Excess production of gastric juice can lead to
➢ acid indigestion, heartburn (acid reflux) and ulcers
Analgesics
• Commonly known as painkillers
Pain
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Pain receptors throughout the body send nerve messages
to the brain
o cause the sensation of pain
Prostaglandins stimulate pain receptors
o released from cells damaged by thermal, mechanical, or
chemical energy.
o cause an inflammatory response: widening of blood
vessels near the injury, increasing pain and causing
swelling
o affect body’s temperature regulation, sometimes causing
How Analgesics Work
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Analgesics block the pathway between pain receptors and the brain
Mild analgesics block pain at the site of injury by preventing the release of
prostaglandins
o also relieve inflammation and fever
•
o known as non-narcotics: do not interfere with the brain
Strong analgesics alter the perception of pain
o bind to opioid receptors, blocking the transmission of pain signals
between brain cells
o known as narcotics: interfere with the brain and may cause
drowsiness and changes in behavior/mood.
o Most effective painkillers
o Usage must be monitored due to potential side-effects and problems
Mild Analgesics: Aspirin
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Aspirin comes from salicin in willow bark (converted
to salicylic acid in body).
The Bayer company made an ester
derivative of salicylic acid that
doesn’t taste awful and called it
aspirin.
Structures of Salicylic Acid and Aspirin
Salicylic acid
Aspirin
Advantages and Disadvantages of Aspirin
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Advantages
Reduces pain, fever, and
inflammation by blocking
the synthesis of
prostaglandins
Blood anti-coagulant
Regular intake of low dose
of aspirin may reduce the
risk of colon cancer
Disadvantages
Irritation/ulceration of
stomach or first section of
small intestine (bleeding).
Intensified if taken with
ethanol. (Can be alleviated
with coating or buffering)
Some (especially
asthmatics) are allergic
Linked to Reye’s syndrome
in kids under 12.
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Paracetamol (AKA acetaminophen)
•
Thought to work by reducing prostaglandins production
in the brain, not the rest of the body.
Advantages and Disadvantages of
Paracetamol
Advantages
Unlikely to irritate stomach
Allergic rxns rare
safe for children
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Disadvantages
Overdose/chronic use can
cause kidney, liver, and
brain damage
Toxic effects increased if
used with ethanol
Does not reduce
inflammation
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Aspirin
Paracetamol
Analgesic (painkiller)
yes
yes
Antipyretic (reduces fever)
yes
yes
Reduces inflammation
yes
no
Side-effects
stomach wall irritant, blood
anti-coagulant
does not irritate stomach
wall
Severe side-effects (overdosage)
Reye’s syndrome in
children
serious kidney, liver, and
brain damage
Synergistic effect with
alcohol
increased risk of stomach
bleeding
toxic side-effects can be
increased
Allergic reactions
relatively common
rare
Recommended use for
children
no
yes
Strong Analgesics
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opioids, aka narcotics
related to Opium
o extract of poppy seeds
drugs derived:
o codeine, morphine
and heroin
act on central nervous system, blocking the
perception of pain
Increasing Narcotic and
Analgesic Effect
codeine < morphine < heroin
Effects and Uses
• narcotic effects
• block perception of pain
• cause constipation
• suppress cough reflex
• cause the pupil to constrict
Codeine
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•
Source : Raw
Opium(0.5%)
Uses:
o preparation with drugs
in the second stage of
pain management
 such as aspirin or
paracetamol
o cough medications
o short-term treatment of
Codeine Structure
tertiary
amine
alcoho
l
2 ethers
Morphine
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•
Source: Raw Opium(10%)
Uses:
o management of severe
pain
 such as advanced
cancer
o must be regulated by a
professions as it is
HABIT FORMING
Morphine Structure
tertiary
amine
alcohols
ether
Diamorphine (heroin)
•
Source:
o found in opium
o obtained by reaction of
morphine
•
Heroin structure
o “Semi-Synthetic” drug
Uses:
o medical relief of severe pain
o most rapidly acting
o most abused drug
o produces euphoric effects
 high potential for
addiction and increasing
tolerance
ester ethanoate
tertiary
amine
ether
Comparing Morphine to Heroin
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Heroine derived from Morphine
Heroin is less polar
o -OH + ethanoic acid converted to esters
Heroin is more lipid soluble
o crosses blood-brain barrier quickly
o (why it is faster acting than other opioids)
Heroin can be hydrolyzed to morphine in brain by
reversing esterification process
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Advantages & Disadvantages as
Analgesics
feeling of well being and
contentment
dulls pain
lessens fear and tension
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leads to constipation
reduced libido(sex drive)
loss of appetite
poor nutrition
withdrawal symptoms
possible crime and
social problems
if injected, could result in
HIV and hepatitis