Guanethidine

Guanethidine (Monosulphate) is adrenergic neuron blocking agent that reduces release of catecholamines. It reduces the blood pressure and decreases heart rate. The structure of guanethidine contains a highly basic nitrogen that makes the drug too polar to enter the central nervous system. So, the drug has no central nervous ystem effects seen with many of other antihypertensive agents.

Brands
Adult Dose
Dose: 0.357 to 0.714 mg/kg
Single Dose: 0.54 (0.5355)
Frequency: 24 hourly
Route: PO
Instructions: -
Neonatal
Dose:
Single Dose:
Frequency:
Route:
Instructions: Not recommended in this age group
Paedriatic
Dose: 200 ug/kg
Single Dose: 200 (200)
Frequency: 24 hourly
Route: Oral
Instructions: Gradually Titer the dose
Characteristics
Guanethidine (Monosulphate) is the derivative of Guanethidine. It is of Synthetic origin and belongs to Guanidine. It belongs to Adrenergic Neurone Blockade pharmacological group on the basis of mechanism of action and also classified in Antihypertensive Agents pharmacological group.The Molecular Weight of Guanethidine is 296.40. Its pKa is 8.7.
Contraindications
Guanethidine is contraindicated in conditions like Phaeochromocytoma,Congestive heart failure,Narrow-angle glaucoma,Hypersensitivity.
Effects
The severe or irreversible adverse effects of Guanethidine, which give rise to further complications include Fever, Hypotension, Hypotension, Bradycardia, Diarrhea, Anaemia.Guanethidine produces potentially life-threatening effects which include Renal failure, Cerebral infarction, Fluid retention. which are responsible for the discontinuation of Guanethidine therapy.The signs and symptoms that are produced after the acute overdosage of Guanethidine include Drowsiness, Confusion, Dizziness, Depression, Persistant hypotension.The symptomatic adverse reactions produced by Guanethidine are more or less tolerable and if they become severe, they can be treated symptomatically, these include Dizziness, Headache, Vomiting, Diarrhea, Constipation, Depression, Postural hypotension, Nasal congestion, Dermatitis, Syncope, Failure of ejaculation, Muscle aching, Worsening of claudication, Muscle pain, Loss of appetite, dizziness.
Indications
Guanethidine is primarily indicated in conditions like Dysthyroid lid retraction, Hypertension, Open-angle glaucoma, and can also be given in adjunctive therapy as an alternative drug of choice in Causalgia, Hypertensive crisis, Renal hypertension.
Interactions
Guanethidine is known to interact with other drugs, the details of drug interactions is as follows:DrugDetailsSeverityOnsetManagementAdrenalineCatecholamine stores are depleted from adrenergic nerve endings by guanethidine result in hypertension and cardiovascular adverse effects when coadministered with adrenaline.ModerateMonitor patient blood pressure and heart rate.In hypertensive patient adrenaline is used with caution.AdrenalineAlcoholAmitriptyline (HCl)Chlorpromazine (HCl)Chlorpromazine (HCl)ChlorprothixeneClomipramine (HCl)ClozapineCocaineDesipramine (HCl)Dexamphetamine (Sulphate)DienoestrolDigoxinDopamine (HCl)Guanadrel decreases the hypotensive effect of dopamine by depleting the catecholamine stores from adrenergic nerve ending and letter potentiate the pharmacological effect of epinephrine and inhibit the primarily indirect acting amine.ModerateHypertensive agents used the combination with caution.Dothiepin (HCl)Doxepin (HCl)DroperidolFlupenthixol (HCl and Decanoate)FluphenazineGestodeneHaloperidolHaloperidol competitively decrease antihypertensive effect of guanethidine at adrenergic neuron.ModerateIf interaction occur an alternative antihypertensive can be given and monitoring of blood pressure is advised.Human InsulinHuman Regular InsulinImipramine (HCl)Insulin LisproLevodopaLevodopaLevosulpirideLofepramine (HCl)Theoretical potential for LOFEPRAMINE reducing the HYPOTENSIVE effect of GUANETHIDINE. MetaraminolGuanethidine work by depleting catecholamines stores from adrenergic nerve endings enhance pharmacologic effect of metaraminol while decrease its hypotensive effect.ModerateMonitoring of blood pressure and heart rate is must if this combination is used.In hypertensive patients noradrenaline is used with caution.Noradrenaline (Acid Tartrate)Guanethidine work by depleting catecholamines stores from adrenergic nerve endings enhance pharmacologic effect of noradrenaline while decrease its hypotensive effect.ModerateMonitoring of blood pressure and heart rate is must if this combination is used.In hypertensive patients noradrenaline is used with caution.OlanzapineOxprenololConcomitant use may produce any excessive reduction of sympathetic activity. PerphenazinePhendimetrazinePhendimetrazine tartarate diminishes effect of Guanethidine.PhenterminePhentermine hydrochloride may decrease the hypotensive effect of guanethidine.Phenylephrine (HCl)Guanethidine work by depleting catecholamines stores from adrenergic nerve endings so its hypotensive effect is decresase by phenylephrine whose pharmacological effect is increased by guanethidine.ModerateMonitoring of blood pressure and heart rate is must if this combination is used.In hypertensive patients noradrenaline is used with caution.Phenylpropanolamine (HCl)Porcine InsulinProcarbazineProcarbazine deplete catecholamines and inhibit their breakdown by increasing storage at agrenergic neurons thus antagonize hypotensive effect of guanethidine. ModerateThis combination should be avoided or give a gap of atleast 2 weeks before or after use of any of these drugs.Protriptyline (HCl)RisperidoneThioridazine (HCl)Trazodone (HCl)Trifluoperazine (HCl)Trimipramine (Maleate)Zuclopenthixol These interactions are sometimes beneficial and sometimes may pose threats to life. Always consult your physician for the change of dose regimen or an alternative drug of choice that may strictly be required.
Interfrence
Monitoring of renal function
Risks
Drug should not be given to Cardiac / Hypertensive Patients, Geriatrics, and Neonates.If prescribing authority justifies the benefits of the drug against the possible damages he/she should reevaluate them and consult the reference material and previous studies.
Storage
Tab Store Below 40°C. Protect from Sunlight and Heat.
Warnings
Dose should be increase gradually in small increment. Guanethidine should be given along with thiazide to minimize sodium retention. It should be used with great caution in patients with severe cardiac failure,renal railure, recent myocardial infraction (M.I), in cerebrovascular disease, especially with encephalopathy, asthma and peptic ulcer patients. Avoid alcohol as Guanethidine may worsen its side effects.
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