Neuropathic pain and drug interactions

After a long period of strong pains, Odile H. Furthermore, was operated with a herniated disc 2 months ago. For example, At the end of the hospital, the neurosurgeon had established a progressive titration of Gabapentine to treat neuropathic pain. Meanwhile, But Mrs. For example, H. Nevertheless, was embarrassed by dizziness and nausea. Therefore, The doses were therefore limited to 1,800 mg/day, doses which have proven to be insufficiently effective. Therefore, Today, Ms. Furthermore, H. Therefore, had a consultation with her neurosurgeon, who faced with the lack of pain relief, decides to add to gabapentine, amitriptyline.

What is the context of the prescription? – Neuropathic pain drug interactions

What do you know about the patient? – Neuropathic pain drug interactions

Ms. Similarly, H. Meanwhile, aged 62 regularly comes to the pharmacy her preventive treatment of osteoporosis based on calcium and vitamin D.

For 6 months, she neuropathic pain drug interactions has suffered from irradiating sciatica -type pain in the aggravated leg for effort. Consequently, She first tried to self -redeem with paracetamol, heated patches and essential oils. However, Little by little, the intensity of the pain increased and Mrs. Meanwhile, H. For example, felt that she was losing strength in the leg. In addition, A scanner revealed a herniated disc and the neurosurgeon she consulted, proposed to operate it. Therefore, When he left hospitalization. Similarly, the neurosurgeon had prescribed paracetamol and tramadol over a few days and gabapentine whose dosage has been gradually increased. Therefore, Very embarrassed by undesirable effects. Moreover, the dose of 1800 mg per day could not be exceeded (the maximum recommended dosage is 3,600 mg/d). Nevertheless, Hidden pain, prevent it in particular from sleeping.

What did the doctor say to him? – Neuropathic pain drug interactions

The neurosurgeon explained to him that the tolerated dose of Gabapentine is not enough to relieve neuropathic pain drug interactions it satisfactorily. Consequently, It completes the treatment with progressive doses of amitriptyline. However, He informs Ms. However, H. Additionally, However, that it is an antidepressant. which has analgesic properties independent of its antidepressive properties and an interesting sedative effect on night pain.

Is prescription consistent?

What does the prescription include?

Gabapentine. an antiepileptic GabaPentinoid which acts by blocking the calcium channels voltage-dependents and thus decreases the release of excitative neurotransmitters, such as glutamate.

ATTRIPTYLINE, a tricyclic antidepressant which inhibits the reuptake of serotonin and norepinephrine and thus strengthens the inhibitory paths of pain.

Is it in accordance with the therapeutic strategy?

Yes. the prescription follows the summary of the French recommendations for the treatment of neuropathic pain of the French Society for Study and Pain Treatment (SFETD) of 2020. Gabapentine. treatment of 1^re insufficiently tolerated intention when increasing the doses is completed, in 2^e intention, by a tricyclic antidepressant, amitriptyline.

Are the dosages neuropathic pain drug interactions consistent?

Yes. In case of dual therapy, the SFETD recommends lower maximum dosages than monotherapy. The dose of 1,800 mg per day of gabapentine corresponds to that recommended when used in dual therapy.

The amitriptyline must be gradually started at doses between 3 and 25 mg. Here. Odile begins the treatment with 5 mg and then gradually increases the dosage with the levels of an MG as a function of tolerance up to a maximum of 25 mg.

Are there any interactions?

The association of Gabapentine and Friendship must take into account a risk increased by drowsiness. The patient should be informed and alerting it to driving dangers, as well as advising her alcohol consumption.

Are there contraindications?

No. Ms. H. does not have a cardiac history or known risk factors for angle closure which would contraindicate the use of amitriptyline.

What advice to give?

Regarding amitriptyline

Regarding an initiation of treatment, the terms of neuropathic pain drug interactions administration should be specified and alerted to certain undesirable effects.

Utilisation

The treatment can be started the same evening. The throtttyline oral solution is administered thanks to a drop-down bottle. Position the bottle upside down and vertically to allow the formation of identical drops containing the same amount of amitriptyline. Dilute them possibly in water before administration and preferably take them in the evening to avoid sedative effects.

The order is written here in milligrams. It is therefore a question of explaining to Mrs. H. that she must take 5 drops of amitriptyline (1 mg of amitriptyline equals 1 drop of solution) that it. can increase by 1 mg (therefore 1 drop) per level of 3 days the minimum.

In case of forgetting, if it is noted in the evening, it can be caught. Otherwise, take the following dose at the scheduled schedule and not double the dose.

It is necessary to inform the neuropathic pain drug interactions patient that the effect of the amitriptyline is not immediate: Ms. H. should be able to note a decrease in pain in 2 to 4 weeks. Efficiency will be evaluated during a consultation after 6 weeks of treatment at maximum tolerated doses.

Undesirable

The main side effects are the atropine effects (oral drought. tremors, constipation, visual disturbances, urinary disturbances, tachycardia) and antihistamine (drowsiness, weight gain). A risk of orthostatic hypotension is also very frequently reported. and more rarely an extension of the QT interval to the electrocardiogram.

Constipation and oral drought can be improved by good hydration (1.5 to 2 liters per day). An increase in fiber consumption but also the use of osmotic or ballast laxatives can improve transit. Insist on the importance of a balanced diet (limiting carbohydrate and lipid intake) to counter the risk of weight gain.

Orthostatic hypotension manifestations can be prevented by advising the patient to get up cautiously neuropathic pain drug interactions in two stages. avoiding overheated environments.

The occurrence of palpitations or chest pain may be a sign of a heart disorder that requires warning the prescriber. Likewise. urinary difficulties or a decrease in the volume of urine may be a sign of retention which must be reported quickly to the doctor.

Neuropathic pain drug interactions

Regarding Gabapentine

With regard to a treatment renewal This involves verifying that the patient observes the administration methods in 3 sockets/day. recalls the signs which would require consulting in an emergency (fever, rash, edema of the language or the face).

A week later

Ms. H. Telephone at the pharmacy: she still has pain. she wants to know if while waiting for the amitriptyline to have her effect, she can take tramadol that she has left in her pharmacy cabinet. The pharmacist advises against the concomitant plug of tramadol with amitriptyline, a fortiori in self -medication. Indeed, this association exposes neuropathic pain drug interactions to a serious risk of the occurrence of serotonergic syndrome (diarrhea, tremors, hypersudation, tension, tachycardia, confusion). In addition. it is imperative to discourage tramadol self -medications and warn the patient against the risks of abuse and dependence. It should also be reminded that since the 1^is March 2025. Tramadol prescriptions are necessarily written on a secure prescription, such as that of narcotics. The pharmacist even advises him to bring back the units that remain the next time she will come to. the pharmacy to avoid any misuse of this medication. Furthermore, The pharmacist questions Ms. H. to find out where she is a dose increases in amitriptyline. encourages her to continue her treatment well by reminding her that his effect should start to be felt in a few days.

What do you think?

Fifteen days later, Mrs. H. complains of being enrolled, she has her throat that stings neuropathic pain drug interactions and blocked nose. It requires fervex (paracetamol, ascorbic acid, phéniramine).

Can the pharmacist access his request?

1) The requested specialty can be issued

2) This medication is to be avoided with the treatment of Ms. H.

Answer : It is better not to deliver the product. Phoeniramine is an antihistamine H1 with anticholinergic properties. In the event of association with amitriptyline. there is an addition of atropine adverse effects with increase in the risk of urinary retention, constipation or oral dryness. The sedative effect is also increased. The nasal congestion which Mrs. H. may complain about the amitriptyline (anticholinergic effect). Nose washing with physiological serum must be advised. possibly a food supplement based on plants, devoid of anticholinergic effects, such as Actirub or Activox-Flash’Rub.

With the kind proofreading of Dr François Jedryka. pain assessment and treatment center, CHU Nîmes (Gard), correspondent for the Inserm 1051 team, Montpellier Institute of Neuroscience (Hérault).

Article from the N neuropathic pain drug interactions ° 3557 training notebook, published on April 12, 2025