Gravinate Tablets(DIMENHYDRINATE BP)

presentation and compostion

Tablets; Yellow, scored,uncoated,stamped searle on one side each containing dimenhydrinate B.P 50mg.

Liquid; Cherry flavorful, each 4ml containing dimenhydrinate B.P 12.5 mg.

ampoules; 1 ml ampoules each containing dimenhydrinate B.P 50mg.

Pharmacodynamics:
 Antihistaminic preparation competitive antagonist of H1-histamine receptors on effector cells.it prevents most of the pharmacological effects of histamine-smooth muscle spasms,tissue edema capillary permeability hypotension-urticaria pruritus.it exerts mild anti-inflammatory and local analgesic action .it has marked antiemetic,sedative and hypnotic effects,which are most likely due to its central anticholinergic activity.it diminishes vestibular stimulation and depresses labyrinthine function-An action on the medullary chemoreceptor trigger zone may also be involved antiemetic effect.

Pharmacokinetics:
It is well absorbed from the gastrointestinal tract.concurrent ingestion of food may delay the rate.but not the extent of its absorption and action.it is metabolized in liver.it has high serum protein binding.the onset of action is within1/2-1 h following administration,and its duration is from 3 to 6 h.it is excreted as metabolites,chiefly in urine for 24 h.it crosses the blood-brain and placental barriers,and is distributed into breast milk.

Indications:
Prevention and relief of motion sickness and treatment of vertigo, nausea or vomiting associated with;electroshock therapy,anaesthesia and surgery, labyrinthine disturbances, radiation sickness,and postfenestration syndrome.

Dosage; Oral- Children
4ml of gravinate liquid contains 12.5 mg of dimenhydrinate.the liquid dosage form is recommended for children.For children 5mg/kg daily in 2 or 3 divided doses is recommended.

Children ; 2-6 years; 12.5-25mg( 4-8ml) 2 to 3 times daily.
                 6-12 years; 25mg (8-16 ml) 2 to 3 times daily.
                 or use as directed by the physicaian.
children under 2 years; only on advice of a physician.

Adults ; The adult therapeutic and prophylactic dose is 50 to 100 mg(one or two tablets)three or four times daily. for prevention of motion sickness, the first dose should be given 30 minutes before departure;

Contraindications:
Hypersensitivity to the active ingredient, epilepsy,infants and children under 5 years of age due to increased to anticholinergic agents and their  effects (CNS excitation and increased tendency toward convulsions) narrowangle glaucome, prostatic hypertrophy,urinary retention, severe hepatic function impairment.

Precautions and warnings:
Patients should be warned to inform physician of use report promptly any occurring gastrointestinal disturbances during administration,because of risk of developing paralytic ileus and impaired diagnosis of appendicitis.it should not be administered under 5 and to patients in advanced age.it may mask the symptoms of toxicity of other medication.it may inhibit the cutaneous histamine response in skin tests using allergen extracts and produce falsenegative results,therefore its use should be discontinued at least 72 h befor testing.


Side Effects:
Signs and symptoms of hypersensitivity-skin rash,stomach upset and pain,tiredness weakness,drowsiness, dryness of mouth blurred vision which are transient or decrease after dose-reduction and may be prevented by concurrent use of caffeine.prolonged use may decrease or inhibit salivary flow and lead to the development of caries,periodontal disease oral candidiasis,and discomfort.it increases photosensitivity. if these effect are very pronounced,the preparation-should be withdrawn.


Overdosage:
Manifestation of anticholinerguc effect, which are frequent in children(dryness of mouth, nose and throat,redness of face,difficult breathing, severe drowsiness,tiredness and weakness)cardiac arrhythmia;CNS depression. specific treatment-vasopressors(not epinephrine,since it may further lower blood pressure),oxygen,and intravenous fluid infusions.cautious use of stimulants(analeptics) because they may cause seizures.


Storage Instructions:
                                Store it at controlled temperature and dry place.