For the use of a Registered Medical Practitioner or a Hospital or a Institution only.
DIMENHYDRINATE TABLETS USP (Dimenhydrinate) is an antiemetic. Chemically, Dimenhydrinate is 1H -Purine-2,6-dione, 8-chloro-3,7-dihydro-1,3-dimethyl-, compd. with 2-(diphenylmethoxy)-N,N-dimethylethanamine (1:1);. The molecular formula is C17H21NO·C7H7ClN4O2 and molecular weight is 469.96.
STRUCTURAL FORMULA :
Its structural formula is :
Each uncoated tablet contains :
Dimenhydrinate USP 50 mg
Dimenhydrinate, a monoethanolamine derivative, is a sedating antihistamine with antimuscarinic and significant sedative effects. While the precise mode of action of dimenhydrinate is not known, it has a depressant action on hyperstimulated labyrinthine function.
Dimenhydrinate is well absorbed from the gastro-intestinal tract after oral dosing with extensive first-pass effect. The drug is metabolised in the liver and excreted usually as metabolites in the urine. The drug is highly bound to plasma proteins and is widely distributed in the body. Following oral administration, the effects develop in about 30 minutes and are maximal within 1-2 hours and last for 3-6 hours.
Dimenhydrinate is used mainly as an anti-emetic in the prevention and treatment of motion sickness; irradiation sickness, postoperative vomiting, drug-induced nausea and vomiting, and the symptomatic treatment of nausea and vertigo due to Meniere’s disease and other labyrinthine disturbances.
DIMENHYDRINATE TABLETS USP is for oral use only.
For motion sickness it is usually given in doses of 50 mg three times daily, the first dose for preventing motion sickness being taken about 30 minutes before the journey. For other treatment, 4-hourly administration may be required. Doses of 100 mg may be required but a daily total of 300 mg should not usually be exceeded.
2 to 6 years : 12.5 to 25 mg two to three times daily. Not more than 75 mg should be given in any 24 hours. Do not exceed the stated dose. 7 to 12 years : 25 to 50 mg two to three times daily. Not more than 150 mg should be given in any 24 hours. Do not exceed the stated dose.
Same as adult dose.
Childrens under 2 years old and patients with a history of hypersensitivity to dimenhydrinate or its components (diphenhydramine or 8-chlorotheophylline) should not be treated with dimenhydrinate. In patients with porphyria. DIMENHYDRINATE TABLETS USP contains lactose which is contra-indicated in patients with galactosaemia, the glucose-galactose malabsorption syndrome, or lactase deficiency.
Dimenhydrinate should be used with caution in patients with epilepsy
- prostatic hypertrophy or urinary retention
- hepatic diseases
- pyloroduodenal obstruction
In patients with renal impairment, a reduction in the dose of any antihistamine (e.g. dimenhydrinate) may be necessary. Use in children under 6 years old should only be under professional advise. Diphenhyramine should not be taken with cough and cold medicines in children aged 2-6 years old. Children and the elderly are more susceptible to the side effects. It has been suggested that Dimenhydrinate could mask warning symptoms of damage caused by ototoxic drugs such as the amino-glycoside antibiotics. Patients with rare hereditary problems of galactose intolerance, the Lapp lactase deficiency or glucose-galactose malabsorption should not take this medicine. Dimenhydrinate should be used with caution in patients having conditions which might be aggravated by anticholinergic therapy (i.e., prostatic hypertrophy, stenosing peptic ulcer, pyloroduodenal obstruction, bladder neck obstruction, narrow-angle glaucoma, bronchial asthma, or cardiac arrhythmias).
Drowsiness may be experienced by some patients, especially with high dosage. This effect frequently is not undesirable in conditions for which the drug is used.
Carcinogenesis, Mutagenesis, Impairment of Fertility :
Mutagenicity screening tests performed with dimenhydrinate, diphenhydramine, and 8-chlorotheophylline produced positive results in the bacterial systems and negative results in the mammalian systems. There are no human data that indicate dimenhydrinate is a carcinogen or mutagen or that it impairs fertility. DIMENHYDRINATE TABLETS USP should be used cautiously in diabetic patients.
Pregnancy : Category B
Reproduction studies have been performed in rats at doses up to 20 times the human dose, and in rabbits at doses up to 25 times the human dose (on a mg/kg basis), and have revealed no evidence of impaired fertility or harm to the foetus due to dimenhydrinate. There are no adequate and well-controlled studies in pregnant women. However, clinical studies in pregnant women have not indicated that dimenhydrinate increases the risk of abnormalities when administered in any trimester of pregnancy. It would appear that the possibility of foetal harm is remote when the drug is used during pregnancy. Nevertheless, because the studies in humans cannot rule out the possibility of harm, dimenhydrinate should be used during pregnancy only if clearly needed.
Nursing mothers :
Small amounts of dimenhydrinate are excreted in breast milk. Because of the potential for adverse reactions in nursing infants from dimenhydrinate, a decision should be made whether to discontinue nursing or to discontinue the drug, taking into account the importance of the drug to the mother.
Paediatric use :
Safety and efficacy in children younger than 2 years of age not established.
Alcohol, CNS depressants :
Enhances CNS depressant effects.
May mask signs of aminoglycoside-related ototoxicity.
Anticholinergic drugs :
Causes additive anticholinergic effects. It is important that the dose of Neperidine, Morphine or other narcotic analgesics and of barbiturates be reduced by ¼ or ½ when used concomitantly.
Laboratory Test Interactions :
May cause false elevation in serum theophylline levels.
Ammonium chloride, amobarbital, butorphanol, chlorpromazine, glycopyrrolate, heparin, hydrocortisone, hydroxyzine, midazolam, pentobarbital, phenobarbital, phenytoin, prednisolone, prochlorperazine, promethazine, tetracycline, theophylline, thiopental, trifluoperazine.
SIDE EFFECTS :
Palpitations, hypotension, tachycardia.
Central Nervous System :
Sedation, hallucinations, delirium, drowsiness, confusion, nervousness, restlessness, headache, insomnia, tingling, heaviness and weakness of hands, vertigo, dizziness, lassitude, excitation.
Fixed drug eruption, photosensitivity.
Eye, Ear, Nose and Throat :
Diminished night vision, decreased colour discrimination, exacerbation of narrow-angle glaucoma, blurred vision, diplopia, nasal stuffiness, dryness of nose and throat.
Nausea, vomiting, diarrhoea, GI distress, constipation, anorexia, dry mouth.
Prostatic enlargement, difficult or painful urination.
Tightness of chest, wheezing, thickening of bronchial secretions.
EFFECTS ON ABILITY TO DRIVE AND USE MACHINES :
Because of the potential for drowsiness, patients taking dimenhydrinate should be cautioned against operating automobies or dangerous machinery.
Drowsiness is the usual clinical side effect. Convulsions, coma, and respiratory depression may occur with massive overdosage.
TREATMENT OF OVERDOSAGE :
In the case of severe overdosage, the stomach should be emptied by gastric lavage. Emetics should not be used. The patient should be kept quiet, particularly in the case of children, to minimise the excitation which occurs. Convulsions may be controlled with Diazepam preferably given intravenously. Since Dimenhydrinate is rapidly metabolised with only traces being recoverable in the urine, diuresis is of little, if any, value.
Store below 30°C (86°F), protected from moisture and light. Do not refrigerate.
SHELF LIFE :
24 months from the date of manufacture.
DIMENHYDRINATE TABLETS USP contains Dimenhydrinate 50 mg.
3 Strips of 10 Tablets per Box.
Disclaimer : For the use of a Registered Medical Practitioner or a Hospital or a Institution only. Also it is not intended to be used by healthcare professionals or patients for the purpose of prescribing or administering these products. Questions regarding the complete and current content of product labeling / specification / presentation should be directed to SGPharma.