Diseases of Tetrapyrrole Metabolism - Refsum Disease and the Hepatic Porphyrias Medication

Updated: Jun 28, 2018
  • Author: Norman C Reynolds, Jr, MD; Chief Editor: Stephen A Berman, MD, PhD, MBA  more...
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Medication

Medication Summary

Two medical therapies are effective in aborting porphyric attacks: IV 10% dextrose in water (D10W) and IV hemin (ie, hematin). Experienced patients with porphyria consume foods high in sugar (eg, candy, ice cream) when they feel an impending attack. If anxious feelings are not episodic but chronic, low dose loxapine is helpful and safe on a regular basis. Injectable hemin (Panhematin) is now approved by the FDA for women with catamenial patterns of exacerbation.

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Intravenous Nutritional Therapy

Class Summary

Glucose is used most commonly. The "glucose effect" reverses or aborts acute porphyric attacks by reducing the rate of porphyrin synthesis using normal endogenous energy metabolism. The "glucose effect" should be reserved for patients with mild pain and no paresis or as a stopgap measure while waiting for hematin.

Dextrose (D-Glucose)

Administered IV to hospitalized patients. Observe carefully for what can become a rapidly changing situation using the first of 2 inpatient drugs of choice. If therapeutic control lost, the patient is switched to IV hemin. Prior to admission, oral sugar loading can be tried. Standard solution is D10W.

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Biologicals

Class Summary

Hemin [17, 18] (ie, hematin) infusion is designed specifically for use in reversing severe acute porphyric attacks. It is also indicated for women who experience recurring attacks associated with their menstrual cycles. After acute attacks are aborted, the hemin can be administered again, either weekly or monthly in the more refractory individuals, when pain complaints initiate a recurring attack.

Hemin (Panhematin)

Enzyme inhibitor derived from processed RBCs and iron-containing metalloporphyrin. Previously known as hematin, term used to describe chemical reaction product of hemin and sodium carbonate solution. Generally used as second DOC (to follow D10W unless prior use suggests that it is superior in a given patient, a patient is at risk for severe diabetic ketoacidosis, or initial D10W treatment fails to stabilize the acute porphyric episode within 2 d). Patients should be well hydrated to avoid (reversible) renal shutdown. "Glucose effect" should be tried initially if possible.

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Anticonvulsants

Class Summary

These agents control idiopathic seizures in patients with manifest porphyrias or in whom porphyric carrier status is suspected.

Gabapentin (Neurontin)

Has properties in common with other anticonvulsants, but most importantly is not metabolized in liver, which makes it safe for use in hepatic porphyrias.

Exact mechanism of action not known. Structurally related to GABA but does not interact with GABA receptors.

Levetiracetam (Keppra)

Used as adjunct therapy for partial seizures and myoclonic seizures. Also indicated for primary generalized tonic-clonic seizures. Mechanism of action is unknown.

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Antipsychotics

Class Summary

These agents are useful in treating hepatic porphyrias, which are recurring anxious feelings not necessarily associated with impending porphyric attack.

Loxapine succinate (Loxitane)

Safety of medication use in hepatic porphyrias is key to maintaining health and avoiding attacks. Loxapine is well tolerated and useful for recurring anxious feelings common in porphyrias. Should be used for recurrent anxious feelings not associated with impending porphyric crisis. Treatment for the latter is noted under IV dextrose use and is initiated by using high oral sugar intake followed by IV dextrose in a hospital setting for close observation. Treatment for the former can be either low-dose maintenance or as needed.

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