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 ulcers

Examples of Antacids

❖ Al(OH) 3 ➢ how does it work? ■ Al(OH) 3 (s) + 3HCl (aq) → AlCl 3 (aq) + 3H 2 O (l) ❖ Mg(OH) 2 ➢ how does it work?

■ Mg(OH) 2 (s) + 2HCl (aq) → MgCl 2 (aq) + 2H 2 O (l) ❖ Many antacid formulations include both Mg and Al ➢ ➢ Mg is fast acting and Al provides long lasting relief Intake of Al is often closely monitored due to links between Al and

Examples of Antacids (cont.)

❖ NaHCO 3 ➢ how does it work? ❖ ■ NaHCO 3 (aq) + HCl (aq) → NaCl(aq) + H 2 O(l) + CO 2 (g) CaCO 3 ➢ how does it work?

❖ ❖ ■ CaCO 3 (s) +2HCl (aq) → CaCl 2 (aq) + H 2 O + CO 2 (g) Since CO 2 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

• •

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 o cause an

inflammatory response

: widening of blood vessels near the injury, increasing pain and causing swelling affect body’s temperature regulation, sometimes causing fever

How Analgesics Work

• • • 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 o known as

non-narcotics :

do not interfere with the brain

Strong analgesics

alter the

perception

of pain o also relieve inflammation and fever 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 o Most effective painkillers Usage must be monitored due to potential side-effects and problems with dependence

Mild Analgesics: Aspirin

• • 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 • • • 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.

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 • • • Disadvantages Overdose/chronic use can cause kidney, liver, and brain damage Toxic effects increased if used with ethanol Does not reduce inflammation

Analgesic (painkiller) Antipyretic (reduces fever) Reduces inflammation Side-effects Severe side-effects (over dosage) Aspirin yes yes yes Paracetamol yes yes no stomach wall irritant, blood anti-coagulant does not irritate stomach wall Reye’s syndrome in children serious kidney, liver, and brain damage Synergistic effect with alcohol Allergic reactions Recommended use for children increased risk of stomach bleeding toxic side-effects can be increased relatively common no rare yes

Strong Analgesics

• • 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

• • Source : Raw Opium(0.5%) Uses: o preparation with drugs in the second stage of pain management  such as aspirin or paracetamol o o cough medications short-term treatment of diarrhoea Codeine Structure

tertiary amine

l alcoho 2 ethers

Morphine

• • Source: Raw Opium(10%) Uses: o management of severe pain  such as advanced cancer Morphine Structure

tertiary amine

alcohols o must be regulated by a professions as it is HABIT FORMING

ether

Diamorphine (heroin)

• Source: o found in opium • o obtained by reaction of morphine o “Semi-Synthetic” drug Uses: Heroin structure o medical relief of severe pain o most rapidly acting

tertiary amine

o most abused drug o produces euphoric effects  high potential for addiction and increasing tolerance

ether

o dependence leads to ester ethanoate

Comparing Morphine to Heroin

• • • • 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

• • •

Advantages & Disadvantages as

feeling of well being and contentment dulls pain

Analgesics

lessens fear and tension • • • • • • 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