eMedicine Specialties > Dermatology > Metabolic Diseases
Variegate Porphyria: Treatment & Medication
Updated: Feb 18, 2009
- Overview
- Differential Diagnoses & Workup
- Treatment & Medication
- Follow-up
Treatment
Medical Care
Management of acute porphyric attacks is complex and has been the subject of several reviews,3,8,20,27,28 which are the sources of most of the following guidelines.
Individuals with any acute porphyria must be informed of the risks of encountering the factors that can exacerbate the disease. Patients must avoid hazardous medications, and physicians must avoid administering them to those at risk. Most of these drugs are inducers of hepatic cytochrome P450, formation of which requires heme, thereby accelerating heme synthesis. Protoporphyrinogen oxidase deficiency then leads to accumulation of the porphyrins and porphyrin precursors that cause symptomatic variegate porphyria.
While most attacks of variegate porphyria appear to be drug induced, in some cases, the inducing factor is uncertain. Therefore, minimizing exposure to factors known to induce attacks in other acute porphyrias is prudent. Thus, avoidance of carbohydrate-restricted diets, moderation of alcohol intake, and smoking cessation is rational advice. Steroid hormonal fluctuations seem generally better tolerated by women with variegate porphyria than those with acute intermittent porphyria but cannot be considered negligible risks. Necessary hormone therapy should be initiated with caution. Prompt treatment of infections and other stressors is recommended. A bracelet or necklace tag identifying the wearer as having variegate porphyria can prevent inadvertent administration of hazardous drugs in emergency situations in which the patient cannot give a history. Medical management of an acute attack is complex; obtaining advice from experts early in its course is strongly recommended.
- Extensive lists of the drugs and chemicals that are considered risky or believed safe can be obtained from several sources, including current textbooks and journal reviews. Online sources include the American Porphyria Foundation, the University of Cape Town Porphyria Service, and the University of Queensland Porphyria Research Unit.
- These lists should only be considered general guides and can be confusing because some drugs appear on both "safe" and "unsafe" lists. Further, drugs on some unsafe lists are considered usable in patients with porphyrias by some authorities.
- Porphyric patients appear to vary widely in tolerance of specific agents, even those well known to be porphyrinogenic.
- Minimizing any drug usage is wise in porphyric individuals; however, when necessary, choose the safest possible agent after a careful review of lists and recommendations.
- Contentious agents should only be used in circumstances that allow for careful monitoring for adverse events.
- Extreme carbohydrate-restricted dieting or fasting should be avoided. Individuals with variegate porphyria who sense an impending attack should immediately consume a source of glucose (eg, candy, soft drinks, fruit juices) and seek medical care. Intravenous infusions or high oral consumption (300-500 g/d) of glucose may abort attacks if given early. Glucose reduces the activity of hepatic aminolevulinic acid synthase, the rate-controlling enzyme of hepatic heme synthesis.29
- Intravenous infusion of a heme-analogue acts to replete the hepatic free heme pool, thereby repressing aminolevulinic acid synthase.30 Heme should be given early in attacks, particularly those that are severe or are not responsive to symptomatic management, fluids, and carbohydrates within a day. In the United States, the analogue hemin is available (Panhematin, Ovation Pharmaceuticals; Deerfield, Ill). In other parts of the world, heme arginate is available as Normosang from Leiras Medica, Helsinki, Finland.
- Women with acute porphyrias who experience cyclic attacks in the week prior to menstruation may benefit from suppression of ovulation by exogenous luteinizing hormone–releasing hormone agonist therapy.31 Cyclic attacks are more characteristic of acute intermittent porphyria than variegate porphyria.13
- Management of fluid and electrolyte imbalances, particularly hyponatremia and hypomagnesemia, is critical during attacks. Intravenous fluid replacement should be with 5% dextrose in saline rather than in water. Experience in several porphyria centers with (1) clonazepam, diazepam, magnesium sulfate, or gabapentin to control seizures; (2) with propanolol to effect beta-blockade to control severe tachycardia and hypertension; (3) with morphine or meperidine for severe pain; and (4) with a phenothiazine to reduce nausea and vomiting, agitation, and anxiety supports the safety and efficacy of these agents.
- Mild attacks (those in which pain levels can be adequately addressed by standard doses of acetaminophen, aspirin, or codeine and in which vomiting does not develop) may remit over 1-2 days with conservative management. Any porphyrinogenic drug must be eliminated, and adequate fluid and carbohydrate intake must be ensured. If improvement is not observed within this time frame, administration of a heme analogue is indicated. Obtaining this "orphan drug" may require delivery from a remote source; a supplier should be contacted as soon as an attack is recognized.
Surgical Care
Liver transplantation for alcoholic cirrhosis in a patient with concurrent variegate porphyria followed by recovery of the porphyria has been reported.32 Whether variegate porphyria alone would ever be sufficient indication for liver transplantation would require a stringent risk/benefit analysis.
Consultations
- Consultation with a porphyria expert may be helpful in managing an acute attack. Lists of physicians with expertise in porphyrias and of laboratories for analysis of porphyrins and porphyrin precursors are available through the American Porphyria Foundation. A particularly comprehensive guide to diagnosis and therapy of variegate porphyria can be found through the University of Cape Town Porphyria Service.
- Consultation with a dermatologist is recommended for sun avoidance/protection measures and treatment of infected skin lesions.
- Consultation with an anesthesiologist is required for the selection of safe anesthetic agents for any needed surgery.
- Consultation with a neurologist for evaluation and treatment of neuropathy is indicated. Rehabilitation medicine services may be needed for recovery of neuromotor deficits over a several-month period.
- Consultation with a gynecologist should be sought if hormonal therapies are considered.
- A medical geneticist can assist in counseling patients and families about the heritability and penetrance of variegate porphyria.
Diet
Carbohydrate restriction should be avoided. Meals should provide adequate sources of complex carbohydrates to maintain blood glucose levels in reference ranges.
Medication
The goals of pharmacotherapy are to reduce morbidity and to prevent complications.
Heme analogues
Infusion of hemelike agents rapidly restores the free-heme pool in hepatocytes, thereby exerting negative feedback repression on the rate-limiting enzyme of heme synthesis. Prompt use may prevent an attack from causing neuronal degeneration.
Hemin (Panhematin)
Enzyme inhibitor derived from processed red blood cells that is an iron-containing metalloporphyrin. Previously known as hematin, a term used to describe the chemical reaction product of hemin and sodium carbonate solution. Has anticoagulant effect and may cause thrombophlebitis at infusion site. Must be reconstituted from lyophilized powder. Reconstitute with human serum albumin 25% (132 mL of 25% human serum albumin to 1 vial of hemin [301 mg heme]) and infuse into large vein to reduce risk of thrombophlebitis.
Adult
3-4 mg/kg/d IV for 4 d (up to 14 d prn);
1-4 mg/kg/d IV over 10-15 min for 3-14 d, based on clinical signs; in severe cases, may repeat no earlier than q12h, not to exceed 6 mg/kg/24h
Pediatric
Not established
May further increase effect of anticoagulants
Documented hypersensitivity
Pregnancy
C - Fetal risk revealed in studies in animals but not established or not studied in humans; may use if benefits outweigh risk to fetus
Precautions
Attacks of porphyria may progress to neuronal damage; prompt use may prevent attack from causing neuronal degeneration, but not effective in repairing existing neuronal damage; asymptomatic and reversible renal shutdown, oliguria, and increased nitrogen retention have occurred; no worsening of renal function has been seen with recommended dosages; monitor coagulation profile if patients have been on anticoagulation therapy; very large doses can cause hemolysis and transient renal failure
Heme arginate
Not currently available in the United States. Fewer adverse effects than hemin.
Adult
3 mg/kg/d IV for 3-4 d or longer if needed; alternatively, 250 mg/d IV mixed with 100 mL human serum albumin infused over 20-30 min for 2-4 d
Pediatric
Not established
May further increase effect of anticoagulants
Documented hypersensitivity
Pregnancy
C - Fetal risk revealed in studies in animals but not established or not studied in humans; may use if benefits outweigh risk to fetus
Precautions
Luteinizing hormone-releasing hormone analogues
These agents decrease endogenous estrogen and progesterone production. The infrequency of menses-related attacks in variegate porphyria would make this therapy infrequently considered.
Leuprolide (Lupron)
Suppresses ovarian and testicular steroidogenesis by decreasing LH and FSH levels.
Adult
1 mg SC qd; alternatively, Lupron Depot at 7.5 mg qmo
Pediatric
Not established
None reported
Documented hypersensitivity; undiagnosed vaginal bleeding; spinal cord compression; pregnancy
Pregnancy
X - Contraindicated; benefit does not outweigh risk
Precautions
Long-term use may cause osteoporosis and endometrial atrophy with vaginal bleeding; supplemental oral calcium (1500 mg/d) should be given with long-term use; reduction in bone density can be treated with bisphosphonates; supplemental estrogen therapy may be needed to relieve uterine bleeding; transdermal or oral estradiol is often tolerated and should be cautiously tried if therapy >6 mo; urinary tract obstruction, tumor flare, and bone pain may occur; monitor patients for weakness and paresthesia
Beta-adrenergic blocking agents
These agents reduce sympathetic hyperactivity.
Propranolol (Inderal)
Has membrane-stabilizing activity and decreases automaticity of contractions. Not suitable for emergency treatment of hypertension. Do not give IV in hypertensive emergencies.
Adult
40-240 mg PO bid, up to 640 mg/d
Pediatric
2-4 mg/kg/d PO divided bid
Coadministration with aluminum salts, barbiturates, NSAIDs, penicillins, calcium salts, cholestyramine, or rifampin may decrease effects; calcium channel blockers, cimetidine, loop diuretics, and MAOIs may increase toxicity; toxicity of hydralazine, haloperidol, benzodiazepines, and phenothiazines may increase
Documented hypersensitivity; uncompensated congestive heart failure; bradycardia; cardiogenic shock; A-V conduction abnormalities
Pregnancy
C - Fetal risk revealed in studies in animals but not established or not studied in humans; may use if benefits outweigh risk to fetus
Precautions
Beta-adrenergic blockade may decrease signs of acute hypoglycemia and hyperthyroidism; abrupt withdrawal may exacerbate symptoms of hyperthyroidism, including thyroid storm; withdraw drug slowly and monitor closely
Opiate analgesics
These agents provide relief of severe abdominal and/or other pain. Very large doses may be required over the course of a day.
Morphine sulfate (Duramorph, Astramorph, MS Contin)
DOC for analgesia owing to reliable and predictable effects, safety profile, and ease of reversibility with naloxone. Various IV doses are used; commonly titrated until desired effect obtained.
Adult
3-12 mg IV/IM repeat q3-4h prn
Pediatric
Infants and children: 0.1-0.2 mg/kg/dose IV/IM/SC q2-4h prn; not to exceed 15 mg/dose; may initiate at 0.05 mg/kg/dose
Phenothiazines may antagonize analgesic effects of opiate agonists; TCAs, MAOIs, and other CNS depressants may potentiate adverse effects of morphine with coadministration
Documented hypersensitivity; hypotension; potentially compromised airway where establishing rapid airway control would be difficult
Pregnancy
C - Fetal risk revealed in studies in animals but not established or not studied in humans; may use if benefits outweigh risk to fetus
Precautions
Caution in hypotension, respiratory depression, nausea, emesis, constipation, and urinary retention; caution in atrial flutter and other supraventricular tachycardias; has vagolytic action and may increase ventricular response rate
Meperidine (Demerol)
Analgesic with multiple actions similar to those of morphine; may produce less constipation, smooth muscle spasm, and depression of cough reflex than similar analgesic doses of morphine.
Adult
50-200 mg IV/IM q3-4h prn
Pediatric
1-1.8 mg/kg (0.5-0.8 mg/lb) PO/IV/IM/SC q3-4h prn; not to exceed adult dose
Monitor for increased respiratory and CNS depression with coadministration of cimetidine; hydantoins may decrease effects; avoid with protease inhibitors
Documented hypersensitivity; MAOIs; upper airway obstruction or significant respiratory depression; during labor when delivery of premature infant is anticipated
Pregnancy
C - Fetal risk revealed in studies in animals but not established or not studied in humans; may use if benefits outweigh risk to fetus
Precautions
Caution in patients with head injuries because may increase respiratory depression and CSF pressure (use only if absolutely necessary); caution when using postoperatively and with history of pulmonary disease (suppresses cough reflex); because of tolerance, substantially increased dose levels may aggravate or cause seizures even if no prior history of convulsive disorders; monitor closely for morphine-induced seizure activity if prior history of seizures
Antiemetics/sedatives
These drugs reduce nausea and vomiting, control anxiety and agitation, and potentiate analgesia.
Chlorpromazine (Thorazine)
Mechanisms responsible for relieving nausea and vomiting include blocking postsynaptic mesolimbic dopamine receptors, anticholinergic effects, and depression of RAS. Blocks alpha-adrenergic receptors and depresses release of hypophyseal and hypothalamic hormones. Slow IV infusion (patient lying flat) when symptoms persist; 25-50 mg with 500-1000 mL of NS; monitor blood pressure.
Adult
10-50 mg IM q4-6h repeat prn
Pediatric
Not established
Other CNS depressants, anticholinergics, or anticonvulsants; antihypertensives may cause additive effect; coadministration with epinephrine may cause hypotension
Documented hypersensitivity; bone marrow suppression; narrow-angle glaucoma; severe liver or cardiac disease
Pregnancy
C - Fetal risk revealed in studies in animals but not established or not studied in humans; may use if benefits outweigh risk to fetus
Precautions
May cause pseudoparkinsonism; akathisia is a common extrapyramidal reaction in elderly persons; lowers seizure threshold and increases risk of seizures in patients with history of seizures
Anticonvulsants
These agents prevent seizure recurrence and terminate clinical and electrical seizure activity.
Magnesium sulfate
Corrects hypomagnesemia and helps control seizures. Nutritional supplement in hyperalimentation; cofactor in enzyme systems involved in neurochemical transmission and muscular excitability.
Adult
3 g in 0.15 M sodium chloride IV infused over 1 h initially, followed by 1 g/h to achieve a serum magnesium level of 4-8 mEq/L
Pediatric
20-100 mg/kg/dose IV q4-6h prn; in severe cases, may use doses as high as 200 mg/kg/dose
Concurrent use with nifedipine may cause hypotension and neuromuscular blockade; may increase neuromuscular blockade seen with aminoglycosides and potentiate neuromuscular blockade produced by tubocurarine, vecuronium, and succinylcholine; may increase CNS effects and toxicity of CNS depressants and betamethasone and cardiotoxicity of ritodrine
Documented hypersensitivity; heart block; Addison disease; myocardial damage; severe hepatitis
Pregnancy
B - Fetal risk not confirmed in studies in humans but has been shown in some studies in animals
Precautions
Magnesium may alter cardiac conduction, leading to heart block in digitalized patients; monitor respiratory rate, deep tendon reflex, and renal function when electrolyte is administered parenterally; caution when administering because may produce significant hypertension or asystole; in overdose, calcium gluconate 10-20 mL IV of 10% solution can be given as antidote for clinically significant hypermagnesemia
Gabapentin (Neurontin)
Structurally related to GABA but does not interact with GABA receptors; not converted metabolically into GABA or a GABA agonist; not an inhibitor of GABA uptake or degradation. Does not exhibit affinity for other common receptor sites.
Adult
300-600 mg PO q8h
Pediatric
<12 years: Not established
>12 years: Administer as in adults
Antacids may significantly reduce bioavailability (administer at least 2 h following antacids); may significantly increase norethindrone levels
Documented hypersensitivity
Pregnancy
C - Fetal risk revealed in studies in animals but not established or not studied in humans; may use if benefits outweigh risk to fetus
Precautions
Administer 2 h after antacids
Diazepam (Valium)
For acute seizure control by intravenous infusion. Depresses all levels of CNS (eg, limbic and reticular formation), possibly by increasing activity of GABA. Individualize dose and increase cautiously to avoid adverse effects.
Adult
5-10 mg IV q10-15 min; not to exceed 30 mg
Pediatric
0.05-0.3 mg/kg/dose IV/IM over 2-3 min q15-30min; repeat in 2-4 h prn; not to exceed 10 mg
Potentiates phenothiazines and narcotic analgesic agents; hepatic elimination of diazepam is reduced by many drugs, including cimetidine, oral contraceptives, disulfiram, fluoxetine, isoniazid, ketoconazole, metoprolol, propoxyphene, propranolol, and valproic acid
Documented hypersensitivity; narrow-angle glaucoma; open-angle glaucoma; coma; psychosis (requires clinical judgment); ketoconazole; itraconazole
Pregnancy
D - Fetal risk shown in humans; use only if benefits outweigh risk to fetus
Precautions
Increased risk of congenital malformations has been associated with use of minor tranquilizers during first trimester of pregnancy; caution with other CNS depressants, low albumin levels, or hepatic disease (may increase toxicity)
Clonazepam (Klonopin)
Long-acting benzodiazepine that increases presynaptic GABA inhibition and reduces monosynaptic and polysynaptic reflexes. Suppresses muscle contractions by facilitating inhibitory GABA neurotransmission and other inhibitory transmitters. Has multiple indications, including suppression of myoclonic, akinetic, or petit mal seizure activity and focal or generalized dystonias (eg, tardive dystonia). Reaches peak plasma concentration at 2-4 h after oral or rectal administration. Not often used IV in United States.
Adult
1 mg IV for acute seizures
0.5 mg PO bid to prevent recurrent seizures
0.05-0.2 mg/kg/d PO for maintenance
Pediatric
Administer as in adults
Phenytoin and barbiturates may reduce effects; coadministration of CNS depressants increase toxicity
Documented hypersensitivity; severe liver disease, and acute narrow-angle glaucoma
Pregnancy
D - Fetal risk shown in humans; use only if benefits outweigh risk to fetus
Precautions
Caution in chronic respiratory tract disease or impaired renal function; withdrawal symptoms can result from abrupt discontinuation
Oral photoprotectants
These agents may reduce cutaneous photosensitivity.
Beta-carotene (Lumitene)
Effectiveness is uncertain in variegate porphyria, but a clinical trial may be warranted in view of its low-risk profile. Exact mechanism of action not completely elucidated. Patient must become carotenemic before effects are observed. More than an internal light screen may be responsible for effects. May provide a limited level of photoprotection. Causes yellowing of skin (carotenoderma). Any photoprotection afforded increases slowly after drug is commenced over a 4- to 6-wk period. When discontinued, skin color and benefit fade over several weeks.
Adult
120-300 mg PO qd; divided doses may be better tolerated and better absorbed.
Pediatric
30-120 mg PO qd; divided doses may be better tolerated and better absorbed; for very small children, cap may be opened and beadlets inside mixed with applesauce or other easily swallowed foods
Coadministration with vitamin A may result in additive toxic effects.
Documented hypersensitivity
Pregnancy
C - Fetal risk revealed in studies in animals but not established or not studied in humans; may use if benefits outweigh risk to fetus
Precautions
Caution in patients with renal or hepatic impairment; may increase risk for lung cancer in heavy smokers; may cause orange stools and diarrhea or loose stools at onset of therapy that tend to resolve with continued use.
More on Variegate Porphyria |
| Overview: Variegate Porphyria |
| Differential Diagnoses & Workup: Variegate Porphyria |
 Treatment & Medication: Variegate Porphyria |
| Follow-up: Variegate Porphyria |
| References |
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References
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Further Reading
Keywords
VP, porphyria variegata, South African porphyria, protocoproporphyria, mixed porphyria, porphyria cutanea tarda hereditaria, royal malady, porphyrin-heme metabolism, protoporphyrinogen oxidase, protoporphyrinogen oxidase gene
