Chemical formula: C₉H₉Cl₂N₃ Molecular mass: 230.094 g/mol PubChem compound: 2803
Clonidine interacts in the following cases:
Substances with alpha2-receptor blocking properties, such as mirtazapine, may abolish the alpha2-receptor mediated effects of clonidine in a dose-dependent manner.
Clonidine should not be administered concomitantly with α1-adrenergic receptor blockers.
The antihypertensive effect of clonidine may be reduced or abolished and orthostatic hypotension may be provoked or aggravated by concomitant administration of tricyclic antidepressants or neuroleptics with alpha-receptor blocking properties.
Concomitant administration of substances with a negative chronotropic or dromotropic effect such as digitalis glycosides can cause or potentiate bradycardic rhythm disturbances.
The reduction in blood pressure induced by clonidine can be further potentiated by concurrent administration of other hypotensive agents. This can be of therapeutic use in the case of other antihypertensive agents such as diuretics, vasodilators, beta-receptor blockers, calcium antagonists and ACE-inhibitors, but the effect of alpha1-blockers is unpredictable.
The reduction in blood pressure induced by clonidine can be further potentiated by concurrent administration of other hypotensive agents. This can be of therapeutic use in the case of other antihypertensive agents such as diuretics, vasodilators, beta-receptor blockers, calcium antagonists and ACE-inhibitors, but the effect of alpha-1 blockers is unpredictable.
Concomitant administration with clonidine of substances with a negative chronotropic or dromotropic effect such as beta-receptor blockers can cause or potentiate bradycardic rhythm disturbances. It cannot be ruled out that concomitant administration of a beta-receptor blocker will cause or potentiate peripheral vascular disorders.
If clonidine is being given concurrently with a beta-blocker, clonidine should not be discontinued until several days after the withdrawal of the beta-blocker.
Substances which raise blood pressure or induce a sodium ion (Na+) and water retaining effect such as non-steroidal anti-inflammatory agents can reduce the therapeutic effect of clonidine.
Based on observations in patients in a state of alcoholic delirium it has been suggested that high intravenous doses of clonidine may increase the arrhythmogenic potential (QT-prolongation, ventricular fibrillation) of high intravenous doses of haloperidol. Causal relationship and relevance for antihypertensive treatment have not been established.
Serious adverse events, including sudden death, have been reported in concomitant use with methylphenidate. The safety of using methylphenidate in combination with clonidine has not been systematically evaluated.
Patients with a known history of depression should be carefully supervised while under long-term treatment with clonidine as there have been occasional reports of further depressive episodes during oral treatment in such patients.
There are limited amount of data from the use of clonidine in pregnant women. This product should only be used in pregnancy if considered essential by the physician. Careful monitoring of mother and child is recommended.
Clonidine passes the placental barrier and may lower the heart rate of the foetus. Post partum a transient rise in blood pressure in the newborn cannot be excluded.
There is no adequate experience regarding the long-term effects of prenatal exposure.
During pregnancy the oral forms of clonidine should be preferred. Intravenous injection of clonidine should be avoided.
Non-clinical studies do not indicate direct or indirect harmful effects with respect to reproductive toxicity.
Clonidine is excreted in human milk. However, there is insufficient information on the effect on newborns. The use of clonidine is therefore not recommended during breastfeeding.
No clinical studies on the effect on human fertility have been conducted with clonidine.
Non-clinical studies with clonidine indicate no direct or indirect harmful effects with respect to the fertility index.
No studies on the effects on the ability to drive and use machines have been performed.
However, patients should be advised that they may experience undesirable effects such as dizziness, sedation and accommodation disorder during treatment with clonidine. If patients experience the above mentioned side effects they should avoid potentially hazardous tasks such as driving or operating machinery.
Most adverse effects are mild and tend to diminish with continued therapy.
Adverse events have been ranked under headings of frequency using the following convention: Very common ≥/10, Common ≥1/100, <1/10, Uncommon ≥1/1000, <1/100, Rare ≥1/10000, <1/1000, Very rare <1/10000, Not known Cannot be estimated from the available data.
Rare: Gynaecomastia
Common: Depression, Sleep disorder
Uncommon: Delusional perception, Hallucination, Nightmare
Not known: Confusional state, Libido decreased
Very common: Dizziness, Sedation
Common: Headache
Uncommon: Paraesthesia
Rare: Lacrimation decreased
Not known: Accommodation disorder
Uncommon: Sinus bradycardia
Rare: Atrioventricular block
Not known: Bradyarrhythmia
Very common: Orthostatic hypotension
Uncommon: Raynaud’s phenomenon
Rare: Nasal dryness
Very common: Dry mouth
Common: Constipation, Nausea, Salivary gland pain, Vomiting
Rare: Colonic pseudo-obstruction
Uncommon: Pruritus, Rash, Urticaria
Rare: Alopecia
Common: Erectile dysfunction
Common: Fatigue
Uncommon: Malaise
Rare: Blood glucose increased
There are occasional reports of fluid retention during initial stages of oral treatment. This is usually transitory and can be corrected by the addition of a diuretic.
Occasional reports of abnormal liver function tests and two cases of hepatitis have also been reported.
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