Product Information
Registration Status: ActiveNEW ALLERIN EXPECTORANT is approved to be sold in Singapore with effective from 2001-05-15. It is marketed by FAR EAST DRUG COMPANY PTE LTD, with the registration number of SIN11517P.
This product contains Diphenhydramine 12.5mg/5ml,Glyceryl Guaiacolate 50mg/5ml, and Phenylephrine 5mg/5ml in the form of SOLUTION. It is approved for ORAL use.
This product is manufactured by UNITED LABORATORIES INC in PHILIPPINES.
It is a Pharmacy Only Medicine that can be obtained from a pharmacist at a retail pharmacy.
Description
Dimenhydrinate, also known as Dramamine or Gravol, is an over-the-counter drug used to prevent nausea, vomiting, and dizziness caused by motion sickness. Dimenhydrinate is a combination drug composed of [DB01075] and [DB14132] in a salt form, with 53%-55.5% of diphenhydramine, and not less than 44%-47% of 8-chlorotheophylline, calculated on the dried basis. The antiemetic properties of dimenhydrinate are primarily thought to be produced by diphenhydramine's antagonism of H1 histamine receptors in the vestibular system [A1540] while the excitatory effects are thought to be produced by 8-chlorotheophylline's adenosine receptor blockade [A33889]. The addition of 8-chlorotheophylline was initially intended to counteract the sedative effects of diphenhydramine. When used in large doses, dimenhydrinate has been shown to cause a "high" characterized by hallucinations, excitement, incoordination, and disorientation [A1539].
Indication
Dimenhydrinate is indicated for the prevention and treatment of nausea, vomiting, or vertigo of motion sickness.
Mechanism of Action
The mechanism by which some antihistamines exert their antiemetic, anti-motion sickness, and anti-vertigo effects is not precisely known but may be related to their central anticholinergic actions. They diminish vestibular stimulation and depress labyrinthine function. An action on the medullary chemoreceptive trigger zone may also be involved in the antiemetic effect. Dimenhydrinate is a competitive antagonist at the histamine H1 receptor, which is widely distributed in the human brain. Dimenhydrinate's anti-emetic effect is probably due to H1 antagonism in the vestibular system in the brain.
Pharmacokinetics
- Absorption
- Well absorbed after oral administration.
- Distribution
- Metabolism
- Hepatic (cytochrome P-450 system).
- Elimination
Toxicity
Symptoms of overdose include delerium, hallucinations, and excitment. Patients may be violent and confused.
Active Ingredient/Synonyms
(O-Benzhydryl(dimethylamino)ethanol) 8-chlorotheophyllinate | 8-chloro-1,3-Dimethyl-3,7-dihydro-1H-purine-2,6-dione - 2-(diphenylmethoxy)-N,N-dimethylethanamine (1:1) | Benzhydryl-beta-dimethylaminoethylether 8-chlorotheophylline | beta-Dimethylaminoethyl benzhydryl ether 1,3-dimethyl-8-chloroxanthine | Dimenhidrinato | Dimenhydrinatum | Diphenhydramine 8-chlorotheophyllinate | Diphenhydramine 8-chlorotheophylline | Diphenhydramine theoclate | Diphenhydrinate | N,N-Dimethyl-2-diphenylmethoxyethylamine 8-chlorotheophyllinate | O-Benzhydryldimethylaminoethanol 8-chlorotheophyllinate | Dimenhydrinate |
Source of information: Drugbank (External Link). Last updated on: 3rd July 18. *Trade Name used in the content below may not be the same as the HSA-registered product.
Source of information: Drugbank (External Link). Last updated on: 3rd July 18. *Trade Name used in the content below may not be the same as the HSA-registered product.
Description
Phenylephrine is a sympathomimetic amine that acts predominantly on α-adrenergic receptors. It is mainly used to treat nasal congestion, but may also be useful in treating hypotension and shock, hypotension during spinal anaesthesia, prolongation of spinal anaesthesia, paroxysmal supraventricular tachycardia, symptomatic relief of external or internal hemorrhoids, and to increase blood pressure as an aid in the diagnosis of heart murmurs.
Indication
Phenylephrine is mainly used to treat nasal congestion, but may also be useful in treating hypotension and shock, hypotension during spinal anaesthesia, prolongation of spinal anaesthesia, paroxysmal supraventricular tachycardia, symptomatic relief of external or internal hemorrhoids, and to increase blood pressure as an aid in the diagnosis of heart murmurs.
Mechanism of Action
In general, α1-adrenergic receptors mediate contraction and hypertrophic growth of smooth muscle cells. α1-receptors are 7-transmembrane domain receptors coupled to G proteins, Gq/11. Three α1-receptor subtypes, which share approximately 75% homology in their transmembrane domains, have been identified: α1A (chromosome 8), α1B (chromosome 5), and α1D (chromosome 20). Phenylephrine appears to act similarly on all three receptor subtypes. All three receptor subtypes appear to be involved in maintaining vascular tone. The α1A-receptor maintains basal vascular tone while the α1B-receptor mediates the vasocontrictory effects of exogenous α1-agonists. Activation of the α1-receptor activates Gq-proteins, which results in intracellular stimulation of phospholipases C, A2, and D. This results in mobilization of Ca2+ from intracellular stores, activation of mitogen-activated kinase and PI3 kinase pathways and subsequent vasoconstriction. Phenylephrine produces its local and systemic actions by acting on α1-adrenergic receptors peripheral vascular smooth muscle. Stimulation of the α1-adrenergic receptors results in contraction arteriolar smooth muscle in the periphery. Phenylephrine decreases nasal congestion by acting on α1-adrenergic receptors in the arterioles of the nasal mucosa to produce constriction; this leads to decreased edema and increased drainage of the sinus cavities.
Pharmacokinetics
- Absorption
- Completely absorbed after oral administration. It has a reduced bioavailability (compared to pseudoephedrine) following oral administration due to significant first-pass metabolism in the intestinal wall. Compared to IV administration, bioavailability is approximately 38%. Peak serum concentrations are achieved approximately 0.75-2 hours following oral administration. Phenylephrine should be administered parenterally to achieve cardiovascular effects. Occasionally, systemic effects are observed following oral inhalation.
- Distribution
- Metabolism
- Undergoes extensive first-pass metabolism in the intestinal wall and extensive metabolism in the liver. Sulfate conjugation, primarily in the intestinal wall, and oxidative metabolism by monoamine oxidase (MAO) represent the principle routes of metabolism. Glucuronidation occurs to a lesser extent. Phenylephrine and its metabolites are mainly excreted in urine/ .
- Elimination
Active Ingredient/Synonyms
(-)-m-Hydroxy-alpha-(methylaminomethyl)benzyl alcohol | (-)-m-Hydroxy-α-(methylaminomethyl)benzyl alcohol | Benzenemethanol, 3-hydroxy-.alpha.-[(methylamino)methyl]-, (R)- | Benzenemethanol, 3-hydroxy-alpha-((methylamino)methyl)-, (R)- | Benzyl alcohol, m-hydroxy-alpha-((methylamino)methyl)-, (-)- | Fenilefrina | l-(3-Hydroxyphenyl)-N-methylethanolamine | Phenylephrine | Phenylephrinum | R(-)-Phenylephrine | Phenylephrine |
Source of information: Drugbank (External Link). Last updated on: 3rd July 18. *Trade Name used in the content below may not be the same as the HSA-registered product.