Pentazocine Tablets BP 25mg

1. Name Of The Medicinal Product

PENTAZOCINE TABLETS BP 25mg

2. Qualitative And Quantitative Composition

Each tablet contains 25mg Pentazocine Hydrochloride BP.

3. Pharmaceutical Form

White uncoated tablets.

White, circular, biconvex uncoated tablets impressed “C” and the identifying letters “PZ” on one face.

4. Clinical Particulars

4.1 Therapeutic Indications

1) For the relief of moderate to severe pain.

4.2 Posology And Method Of Administration

Adults: The usual initial dosage is 50mg every four hours after meals followed by 25-100mg every three to four hours.

Children 6-12 years: 25mg every three to four hours as required.

Children under 6 years: Not recommended.

Elderly: Dosage should be reduced in the elderly where there is impairment of hepatic or renal function.

For oral use.

4.3 Contraindications

Patients with established respiratory depression, especially in the presence of cyanosis and excessive bronchial secretion, raised intracranial pressure, head injuries or pathological brain conditions where clouding of the sensorium is undesirable. Acute bronchial asthma, in heart failure, secondary to chronic lung disease, porphyria, and in patients known to be hypersensitive to pentazocine and any other ingredients.

4.4 Special Warnings And Precautions For Use

Administer with caution in patients with severely impaired hepatic or renal function, and to those previously on large doses of narcotics.

Caution should be exercised when administering high doses of pentazocine to patients who have suffered a recent myocardial infarction due to increases in heart rate and blood pressure.

Caution should also be observed in patients with hypothyroidism, adrenocortical insufficiency, prostatic hypertrophy and in patients with inflammatory or obstructive bowel disorders.

Patients already receiving MAOI's needs to be cautious before taking opioids. Some opioids can cause CNS excitation or depression. Opioids can be taken after two weeks of MAOI's discontinuation. Pentazocine should not be used on patients already dependent on other opioids as it can produce the symptoms of withdrawal.

After long term treatment (> 3 months) of analgesics with use every second day or more frequently, headache may develop or aggravate. Headache caused by overuse of analgesics (MOH - medication-overuse headache) should not be treated by increasing the dose. In such cases the use of analgesics should be discontinued in consultation with a doctor.

4.5 Interaction With Other Medicinal Products And Other Forms Of Interaction

Agents with sedative action, including phenothiazines and ethyl alcohol can enhance the central depressant effects of pentazocine which are opposed by respiratory stimulants such as doxapram.

As pentazocine is a weak narcotic antagonist, it may provoke withdrawal symptoms if given to narcotic addicts.

Administer with caution to patients receiving MAOI's. Pentazocine should not be used within 14 days of stopping therapy with MAOI's.

4.6 Pregnancy And Lactation

There is no epidemiological evidence for the safety of pentazocine in pregnancy but it has been widely used for many years without apparent ill consequences. Doses which produce maternal toxicity in rats have caused harmful effects in the foetus. Pentazocine can enter the foetal circulation and has the potential to cause opioid effects including central depression and abstinence syndrome in the foetus. There is insufficient data on the secretion of pentazocine in breast milk, so it is recommended that infants of nursing mothers who are receiving high doses of pentazocine, be appropriately monitored.

4.7 Effects On Ability To Drive And Use Machines

As pentazocine may produce sedation, patients should be warned against the performance of potentially hazardous tasks such as driving a car or operating machinery; alcohol may potentiate the sedative effect.

4.8 Undesirable Effects

Normal therapeutic doses side effects are generally of a minor nature. Sedation, the most common effect, is less than that associated with morphine. .

The most frequent side effects are light-headedness, dizziness, nausea, vomiting and sweating. The following side effects have also been reported.

Cardiovascular: transient hypertension, tachycardia, bradycardia, hypotension, circulatory depression, palpitations.

Central and peripheral nervous system: Hallucinations may occur occasionally, dysphoria, disturbances of vision, headache, disorientation, mood changes, nightmares, insomnia, paraesthesia, syncope, euphoria, grand mal convulsions, raised intracranial pressure, confusion, tremor.

Allergic: oedema of the face, flushed skin including facial plethora, skin rashes, urticaria, dermatitis including pruritus.

Gastrointestinal: constipation, dry mouth, ureteric or biliary spasm.

Ophthalmic: miosis.

Respiratory: respiratory depression

Other: urinary retention, constipation, muscle tremor, chills, hypothermia, alterations in rate or strength of uterine contractions during labour, decreased libido or potency, hypotension.

4.9 Overdose

The symptoms of pentazocine overdose will resemble those of morphine and other opioids. They may therefore include somnolence, respiratory depression hypotension, tachycardia, hallucinations, or seizures. Circulatory failure and deepening coma may occur in more severe cases, as may convulsions, particularly in patients who have also ingested other CNS depressants such as alcohol, sedatives/hypnotics or antihistamines.. Adequate measures to maintain ventilation and general circulatory support should be employed.

Gastric lavage and gastric aspiration should be considered where appropriate.

For respiratory depression due to overdosage or unusual sensitivity to pentazocine, parenteral naloxone is a specific and effective antagonist. Initial dose of 0.4 to 0.2mg of naloxone are recommended, repeated at 2-3 minute intervals if needed, up to a total of 10mg. Anti-convulsant therapy may be necessary.

5. Pharmacological Properties

5.1 Pharmacodynamic Properties

Pentazocine hydrochloride is a narcotic opioid analgesic.

Pentazocine has both agonist and antagonist action at opioid receptors. Pentazocine interrupts nociceptive input in the spinal cord. These analgesic effects are probably due to agonist actions at κ-receptors. Pentazocine is a weak antagonist at µ opioid receptors with about one fiftieth the potency of nalorphine.

5.2 Pharmacokinetic Properties

Pentazocine is absorbed from the gastro-intestinal tract; following administration by mouth, peak plasma concentrations are reached in 1-3 hours and the half life is reported to be 2-3 hours. Pentazocine is almost completely metabolised in the liver and only a small proportion of the dose administered appears unchanged in the urine. It diffuses across the placenta.

5.3 Preclinical Safety Data

There are no pre-clinical data of relevance to the prescriber which are additional to that already included in other sections of the SPC.

6. Pharmaceutical Particulars

6.1 List Of Excipients

Also contains: crospovidone, lactose, magnesium stearate, polyvidone, microcrystalline cellulose (E460).

6.2 Incompatibilities

None known.

6.3 Shelf Life

Three years from the date of manufacture.

6.4 Special Precautions For Storage

Store below 25°C in a dry place.

6.5 Nature And Contents Of Container

The product containers are rigid injection moulded polypropylene or injection blow-moulded polyethylene tablet containers with polyfoam wad or polyethylene ullage filler and snap-on polyethylene lids; in case any supply difficulties should arise the alternative is amber glass bottles with screw caps and polyfoam wad or cotton wool. An alternative closure for polyethylene containers is a polypropylene, twist on, push down and twist off child-resistant, tamper-evident lid.

The product may also be supplied in blister packs in cartons:

a) Carton: Printed carton manufactured from white folding box board.

b) Blister pack: (i) 250µm white rigid PVC. (ii) Surface printed 20µm hard temper aluminium foil with 5-7g/M² PVC and PVdC compatible heat seal lacquer on the reverse side.

6.6 Special Precautions For Disposal And Other Handling

Not applicable.

Administrative Data

7. Marketing Authorisation Holder

Actavis UK Limited

(Trading style: Actavis)

Whiddon Valley

BARNSTAPLE

N Devon EX32 8NS

8. Marketing Authorisation Number(S)

PL 0142/0313

9. Date Of First Authorisation/Renewal Of The Authorisation

29.11.90

Renewed: 17.4.96

10. Date Of Revision Of The Text

21.07.2011