Analgesic (also known as a painkiller) is any member of the group of

drugs used to relieve pain .

The word analgesic derives from Greek an- ("without") and

algos ("pain“)

Analgesic drugs act in various ways on the peripheral and

central nervous systems . They are distinct from

anesthetics, which reversibly eliminate sensation.

Analgesics are those drugs that mainly provide

pain relief.

classes of analgesics

- Narcotics chemically based on the morphine molecule such as

morphine and opium

-nonsteroidal anti-inflammatory drugs such as

the

salicylates

-acetaminophen. they include paracetamol (para-

acetylaminophenol, also known in the US as acetaminophen (

Narcotic analgesics (opioids)

derived from opium. The class includes morphine, codeine, and a

number of semi-synthetics including meperidine (Demerol),

propoxyphen (Darvon) and others. The narcotic analgesics vary in

potency, but all are effective in treatment of visceral pain when used in

adequate doses. A variety of dosage forms are available, including oral

solids, liquids, intravenous and intrathecal injections, and

transcutaneous patches.

Opioid Toxicity

Symptoms include subtle agitation, shadows at the periphery

of the visual field, vivid dreams, nightmares, myoclonic jerks,

confusion, paranoia and visual hallucinations. Failing renal

function/dehydration may precipitate these symptoms. The

development of opioid toxicity is dependent on previous opioid

exposure, and the rate of dose escalation. Management

includes rehydration, and reducing the opioid dose.

-NSAIDs -are effective analgesics even at doses too low to have any anti-

inflammatory effects. There are a number of chemical classes, but all

have similar therapeutic effects and side effects. Most are appropriate

only for oral administration; however ketorolac (Toradol) is appropriate

for injection and may be used in moderate to severe pain for short

periods.

-Aspirin and the other non-steroidal anti-inflammatory drugs (NSAIDs)

inhibit cyclooxygenases, leading to a decrease in prostaglandin

production. This reduces pain and also inflammation (in contrast to

paracetamol and the opioids).

-

Acetaminophen

is a non-narcotic analgesic with no anti-inflammatory properties. It is

appropriate for mild to moderate pain. Although the drug is well tolerated

in normal doses, it may have significant toxicity at high doses.

The exact mechanism of action of paracetamol/acetaminophen is

uncertain, but it appears to be acting centrally rather than peripherally

(in the brain rather than in nerve endings).

Because acetaminophen is largely free of side effects at therapeutic

doses, it has been considered the first choice for mild pain, including

that of osteoarthritis.

Paracetamol ToxicityOverdose of paracetamol leads to 'paracetamol toxicity,' which mainly

results into liver injury but is also one of the most common causes of

poisoning all over world. Many people who develop paracetamol toxicity

may feel no symptoms at all in the first 24 hours that follow overdose of

paracetamol. As the paracetamol toxicity increases, signs of liver

failure like low blood sugar, low blood pH, easy bleeding, hepatic

encephalopathymay may develop, abdominal pain and nausea. The risk

of paracetamol toxicity increases with excessive alcohol intake, fasting

or anorexia nervosa, and also with the use of certain drugs like

isoniazid.

The exact mechanism of action of paracetamol/acetaminophen is uncertain, but it appears to be acting centrally rather than peripherally (in the brain rather than in nerve endings). Aspirin and the other non-steroidal anti-inflammatory drugs (NSAIDs) inhibit cyclooxygenases, leading to a decrease in prostaglandin production. This reduces pain and also inflammation (in contrast to paracetamol and the opioids).[citation needed]

Paracetamol has few side effects and is regarded as safe, although intake above the recommended dose can lead to liver damage, which can be severe and life-threatening, and occasionally kidney damage. NSAIDs predispose to peptic ulcers, renal failure, allergic reactions, and occasionally hearing loss, and they can increase the risk of hemorrhage by affecting platelet function. The use of aspirin in children under 16 suffering from viral illness has been linked to Reye's syndrome, a rare but severe liver disorder.

-Topical analgesics

-(topical being those that are applied on the skin) have become much

more popular in recent years. Those applied for local effect include

capsaicin, methylsalicylate, and transdermal lidocaine. Transdermal

fentanyl may be applied for systemic (the entire body in general) effect. In

some cases, these topical agents reduce the need for drug therapy.

-Sales of pain relief patches have increased substantially in recent years.

They are particularly useful for elderly patients who may not want to take

a lot of tablets.

Recommended dosage

Appropriate dosage varies by drug, and should consider the type of

pain, as well as other risks associated with patient age and condition.

For example, narcotic analgesics should usually be avoided in patients

with a history of substance abuse, but may be fully appropriate in

patients with cancer pain. Similarly, because narcotics are more

rapidly metabolized in patients who have used these drugs for a long

period, higher than normal doses may be needed to provide adequate

pain management. NSAIDs, although comparatively safe in adults,

represent an increased risk of gastrointestinal bleeding in patients over

the age of 60.

Precautions

Narcotic analgesics may be contraindicated in patients with

respiratory depression. NSAIDS may be hazardous to patients

with ulcers or an ulcer history. They should be used with care in

patients with renal insufficiency or coagulation disorders.

NSAIDs are contraindicated in patients allergic to aspirin.

Side effects

The primary adverse effects of the narcotic analgesics are addiction,

constipation, and respiratory depression.

Because narcotic analgesics stimulate the production of enzymes that

cause the metabolism of these drugs, patients on narcotics for a

prolonged period may require increasing doses. This is not the same

thing as addiction, and is not a reason for withholding medication from

patients in severe pain.

NSAIDs can lead to ulcers and may cause kidney problems.

Gastrointestinal discomfort is common, although in some cases, these

drugs may cause ulcers without the prior warning of gastrointestinal

distress. Platelet aggregation problems may occur, although not to the

same extent as is seen with aspirin.

Adjuvant analgesics •Tricyclic Antidepressants eg amitriptyline or nortriptyline are first line

treatment for neuropathic pain, which may be only partially controlled by

morphine. Often effective in sub-antidepressant doses, eg 10mg-25mg at

night.

•Anticonvulsants eg gabapentin and sodium valproate are useful as

second line treatment for neuropathic pain.

•NSAIDs eg diclofenac is useful in controlling bone and soft tissue pain.

•Corticosteroids eg dexamethasone, are effective in nerve damage pain

by reducing peri-neural oedema. Reduces headache and confusion in

cerebral metastases.

• Anxiolytics eg diazepam, lorazepam and midazolam, can improve

pain control in conjunction with opioids. Useful in agitated states

and for dyspnoea. Lorazepam is an effective anxiolytic when used

sublingually. Midazolam is a very effective anxiolytic when added to

diamorphine in a continuous subcutaneous infusion.

•Muscle Relaxants eg baclofen, benzodiazepines and quinine are

useful in treating pain associated with muscle spasm. Use with care

as they may cause depression and weakness.

•Antimuscarinics eg hyoscine butylbromide, are useful in relieving

colic pain.

Prescription Drug Abuse- Prescription Drug Addiction

The types of prescription drugs most commonly abused are:

Central Nervous System (CNS) Depressants: Barbiturates, Tranquilizers,

Xanax, Valium, Rohypnol, Placidil, Ativan, Klonopine, Librium, Quaalude

Prescription Painkillers Opioids, narcotics, hydrocodone, morphine,

fentanyl, codeine, Oxycontin, Percocet, Percodan, Darvon, Dilaudid,

Demerol

Prescription Stimulants: Adderall, Ritalin, Concerta, Dexedrine

Addiction

Users need larger and larger doses to get the same effect,

which brings them, continually closer to the fatal dose.

Overdose is more likely to occur when users mix

depressants with alcohol. Users become disoriented,

confused, and can’t remember how much they took. The list

of people who have died from depressants and alcohol is

long.

How are Prescription Painkillers Abused?

Prescription painkillers can be taken orally, or the pills may

be crushed and the powder snorted or injected. A number

of overdose deaths have resulted from the latter routes of

administration, particularly with the drug OxyContin, which

was designed to be a slow-release formulation.

Snorting or injecting opioids results in a rapid release of

the drug into the bloodstream, exposing the person to high

doses and causing many of the reported overdose

reactions.

What Adverse Effects Can be Associated with Prescription Painkillers? Prescription pain medications can produce drowsiness, cause

constipation, and, depending upon the amount taken, depress

breathing. Taking a large single dose could cause severe respiratory

depression or death.

These medications are only safe to use with other substances under

a physician’s supervision. Typically, they should not be used with

alcohol, antihistamines, barbiturates, or benzodiazepines. Because

these substances slow breathing, their combined effects could lead

to life-threatening respiratory depression.

TranquilizersTranquilizers are drugs used to treat anxiety or problems with sleep.

They have a calming effect by depressing the nervous system in a way

similar to alcohol. Tranquilizers are among the most commonly

prescribed psychiatric medications.

In some ways, the term "tranquilizer" is inaccurate. Although they may

produce specific anxiety-reducing effects, the members of the

tranquilizer group of drugs have the same clinical effects as sedatives

such as the barbiturates (downers). The much-sought relaxing and

anxiety-reducing effects of the tranquilizers are simply the early stages

of the biochemical process of sedation. The effects of sedation are a

continuum from relaxation to significant sedation to coma to death.

Central nervous system depressants, including minor

tranquilizers, sedatives, and alcohol, place the user on the

sedation continuum. The specific dosage and drug used

determines how far the user goes on that pathway.

Tranquilizers are frequently abused because of their ability to

reduce anxiety. They are addictive because tolerance

develops rapidly, and more and more are needed to be

effective.

Thank you very much for your kind and

help