Parathyroid hormone interacts in the following cases:
There are no data available in patients with severe renal impairment.
There are no data available in patients with severe hepatic impairment.
Hypercalcaemia of any cause may predispose to digitalis toxicity. In patients using parathyroid hormone concomitantly with cardiac glycosides (such as digoxin or digitoxin), monitor serum calcium and cardiac glycoside levels and patients for signs and symptoms of digitalis toxicity.
Co-administration of alendronic acid and parathyroid hormone may lead to a reduction in the calcium sparing effect, which can interfere with the normalisation of serum calcium. Concomitant use of parathyroid hormone with bisphosphonates is not recommended.
Parathyroid hormone has not been studied in patients with urolithiasis. Parathyroid hormone should be used with caution in patients with active or recent urolithiasis because of the potential to exacerbate this condition.
There are no data from the use of parathyroid hormone in pregnant women. Animal studies do not indicate direct or indirect harmful effects with respect to reproductive toxicity.
A risk to the pregnant woman or developing foetus cannot be excluded. A decision must be made whether to initiate or discontinue treatment with parathyroid hormone during pregnancy taking into account the known risks of therapy versus the benefit for the woman.
It is unknown whether parathyroid hormone is excreted in human milk.
Available pharmacology data in animals have shown excretion of parathyroid hormone in milk.
A risk to the newborns/infants cannot be excluded. A decision must be made whether to discontinue breast-feeding or to discontinue therapy with parathyroid hormone, taking into account the benefit of breast-feeding for the child and the benefit of therapy for the woman.
There are no data on the effects of parathyroid hormone on human fertility. Animal data do not indicate any impairment of fertility.
Parathyroid hormone has no or negligible influence on the ability to drive and use machines. Since neurologic symptoms may be a sign of uncontrolled hypoparathyroidism, patients with disturbances in cognition or attention should be advised to refrain from driving or using machines until symptoms have subsided.
The most frequent adverse reactions among patients treated with parathyroid hormone were hypercalcaemia, hypocalcaemia, and their associated clinical manifestations including headache, diarrhoea, vomiting, paraesthesia, hypoaesthesia and hypercalciuria. In the clinical studies, these reactions were generally mild to moderate in severity and transient, and were managed with adjustments of parathyroid hormone, calcium and/or active vitamin D doses.
Adverse reactions for parathyroid hormone-treated patients in the placebo-controlled study and in post-marketing experience are listed below by MedDRA system organ class and frequency. Frequencies are defined as very common (≥1/10), common (≥1/100 to <1/10), and not known (cannot be estimated from the available data). All adverse reactions identified in post-marketing experience are italicised.
| System organ class | Very common (≥1/10) | Common (≥1/100 to <1/10) | Not known (cannot be estimated from the available data) |
|---|---|---|---|
| Immune system dysorders | Hypersensitivity reactions, (dyspnoea, angioedema, urticaria, rash) | ||
| Metabolism and nutrition disorders | hypercalcaemia, hypocalcaemia | hypomagnesaemia†, tetany† | |
| Psychiatric disorders | anxiety†, insomnia* | ||
| Nervous system disorders | headache*,†, hypoaesthesia†, paraesthesia† | somnolence* | |
| Cardiac disorders | palpitations*,† | ||
| Vascular disorders | hypertension* | ||
| Respiratory, thoracic and mediastinal disorders | cough† | ||
| Gastrointestinal disorders | diarrhoea*†, nausea*, vomiting* | abdominal pain upper* | |
| Musculoskeletal and connective tissue disorders | arthralgia*, muscle spasms† | muscle twitching†, musculoskeletal pain†, myalgia†, neck pain†, pain in extremity | |
| Renal and urinary disorders | hypercalciuria*, pollakiuria† | ||
| General disorders and administration site conditions | asthenia*, chest pain†, fatigue, injection site reactions, thirst* | ||
| Investigations | anti-PTH antibody positive, blood 25-hydroxycholecalciferol decreased†, vitamin D decreased |
* Signs and symptoms potentially associated with hypercalcaemia that were observed in the clinical trials.
† Signs and symptoms potentially associated with hypocalcaemia that were observed in the clinical trials.
Hypercalcaemia and hypocalcaemia were commonly encountered during the dose titration period. The risk for serious hypocalcaemia was greatest after the withdrawal of parathyroid hormone. Cases of hypocalcaemia resulting in seizures have been reported post-marketing.
In the placebo-controlled study, 9.5% (8/84) parathyroid hormone-treated patients and 15% (6/40) placebo-treated patients experienced an injection site reaction, all of which were mild or moderate in severity.
Consistent with the potentially immunogenic properties of medicinal products containing peptides, administration of parathyroid hormone may trigger the development of antibodies. In the placebo-controlled study in adults with hypoparathyroidism, the incidence of anti-parathyroid hormone (PTH) antibodies was 8.8% (3/34) and 5.9% (1/17) in patients who received subcutaneous administration of 50 to 100 micrograms parathyroid hormone or placebo once daily for 24 weeks, respectively.
Across all clinical studies in patients with hypoparathyroidism following treatment with parathyroid hormone for up to 4 years, the immunogenicity incidence rate was 17/87 (19.5%) and did not appear to increase over time. These 17 patients had low titre anti-PTH antibodies and, of these, 3 subsequently became antibody negative. The apparent transient nature of antibodies to PTH is likely due to the low titre. Three of these patients had antibodies with neutralising activity; these patients maintained a clinical response with no evidence of immune-related adverse reactions.
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