RESERPINE

RESERPINE
(re-ser'peen)
Serpalan, Sk-Reserpine
Classifications: rauwolfia alkaloid; antihypertensive;
Therapeutic: antihypertensive

Pregnancy Category: D

Availability

0.1 mg, 0.25 mg tablets

Action

Principal alkaloid of Rauwolfia serpentina. Interferes with binding of serotonin at receptor sites, decreases synthesis of norepinephrine by depleting dopamine (its precursor), and competitively inhibits their reuptake in storage granules. Depletes norepinephrine and serotonin in CNS, peripheral nervous system, heart, and other organs and tissues.

Therapeutic Effect

Sympathetic inhibition seen in small but persistent decrease in BP, frequently associated with bradycardia, and reduced cardiac output. Central effect results in tranquilization and sedation similar to those produced by chlorpromazine.

Uses

Mild essential hypertension and as adjunctive therapy with other antihypertensive agents in the more severe forms of hypertension. Also used in agitated psychotic states, primarily in patients intolerant to phenothiazine or patients who also require antihypertensive medication.

Unlabeled Uses

Reduce vasospastic attacks in Raynaud's phenomenon and other peripheral vascular disorders, and for short-term symptomatic treatment of thyrotoxicosis.

Contraindications

Hypersensitivity to rauwolfia alkaloids; history of mental depression; acute peptic ulcer, ulcerative colitis; patients receiving electroconvulsive therapy; within 7–14 d of MAO inhibitor therapy; pregnancy (category D), lactation. Safe use in children is not established.

Cautious Use

Renal insufficiency; cardiac arrhythmias; cardiac damage; cerebrovascular accident; history of peptic ulcers; epilepsy; bronchitis, asthma; older adults, debilitated patients; gallstones; obesity; chronic sinusitis; parkinsonism; pheochromocytoma.

Route & Dosage

Hypertension
Adult: PO 0.5 mg/d initially, reduced to 0.1–0.25 mg/d
Geriatric: PO Start with 0.05 mg q.d., increase by 0.05 mg per wk

Administration

Oral
  • Give with meals or with milk or other food to minimize possibility of gastric irritation (drug increases gastric secretions).
  • Store in tight, light-resistant containers, preferably at 15°–30° C (59°–86° F), unless otherwise directed by manufacturer.

Adverse Effects (≥1%)

CNS: Drowsiness, sedation, lethargy, mental depression, nervousness, anxiety, nightmares, increased dreaming, headache, dizziness, increased appetite, dull sensorium; prolonged use of large doses: CNS stimulation (parkinsonian syndrome): tremors, muscle rigidity; respiratory depression, convulsions, hypothermia. CV: Bradycardia, edema, orthostatic hypotension, increased AV conduction time (prolonged therapy); angina-like symptoms, arrhythmias, CHF (rare). Special Senses: Nasal congestion, epistaxis, lacrimation, blurred vision; miosis, ptosis, conjunctival congestion (acute toxicity). GI: Dry mouth or excessive salivation, nausea, vomiting, abdominal cramps, diarrhea, reactivation of peptic ulcer (hypersecretion), heartburn, biliary colic. Hematologic: Thrombocytopenic purpura, anemia, prolonged BT. Body as a Whole: Hypersensitivity (pruritus, rash, asthma), muscle aches, dysuria, fixed-drug eruptions. Urogenital: Menstrual irregularities, breast engorgement, galactorrhea, gynecomastia, feminization (males), impaired sexual function, impotence.

Diagnostic Test Interference

Possibility of elevated blood glucose values; however, it is also reported that reserpine may decrease thiazide-induced hyperglycemia. Increase in serum prolactin with chronic administration of rauwolfia alkaloids; overdoses may cause initial increase in excretion of urinary catecholamines; decreases with chronic administration. Large doses may cause initial rise in urinary 5 HIAA excretion. Initial IM doses may increase urinary VMA excretion followed by decrease by end of third day of therapy (with oral or parenteral administration). Possible interference with urinary steroid colorimetric determinations: 17-OHCS and 17-KS.

Interactions

Drug: Diuretics, other hypotensive agents compound hypotensive effects; cardiac glycosides (digoxin) may increase risk of arrhythmias; mao inhibitors may cause excitation and hypertension; cns depressants compound depression; may decrease response to levodopa. Herbal: St. John's wort may antagonize hypotensive effects.

Pharmacokinetics

Peak: 2 h. Distribution: Widely distributed, especially to adipose tissue; crosses blood–brain barrier and placenta; distributed in breast milk. Metabolism: Extensively metabolized to inactive compounds. Elimination: Slowly excreted, 60% in feces within 96 h and 10% in urine. Half-Life: 4.5 and 11.3 h.

Nursing Implications

Assessment & Drug Effects

  • Assess vital signs at intervals prescribed by physician. Compare readings with baseline data and keep physician informed. (Note: Drop in BP may be accompanied by bradycardia.)
  • Lab tests: Periodic CBC with differential, platelet count, serum electrolytes, and plasma glucose.
  • Supervise ambulation as indicated; postural hypotension occurs rarely with usual PO doses but is not uncommon in patients receiving large parenteral doses.
  • Monitor I&O, especially in patients with impaired kidney function. Report changes in I&O ratio and pattern.
  • Full therapeutic effect of oral drug for hypertension may not occur until 2–3 wk of therapy, and effects may persist for as long as 4–6 wk after drug is discontinued.
  • Take special precautions with older adult and obese patients (half-life is reportedly prolonged in obese patients). Anticipate increased incidence of adverse effects.
  • Be aware that mental depression is a serious adverse effect and may be severe. It occurs most commonly in high dosage regimens (e.g., 0.5–1 mg/d or more) and may not appear until 2–8 mo of therapy and may last for several months after drug is withdrawn.

Patient & Family Education

  • Take drug at the same time each day, do not skip or double doses, and do not stop therapy without advice of physician.
  • Do not drive or engage in potentially hazardous activities until response to drug is known.
  • Learn about possible adverse effects and report promptly to physician.
  • Report the following possible beginning symptoms of depression: early morning insomnia, anorexia, inability to concentrate, despondency, self-deprecation, attitude of detachment, mood swings, or impotence. Hospitalization may be necessary.
  • Make position changes slowly, particularly from recumbent to upright posture, and lie down or sit down (head-low position) if patient feels faint. Do not take hot showers or hot tub baths, and do not to stand still for prolonged periods. Report symptoms of dizziness or light-headedness to physician.
  • Check for edema and record weight daily to help make a distinction between weight gain from edema and that from increased appetite. Consult physician about gain of 1–2 kg (3–5 lb) in 1 wk.
  • Do not take OTC medications without consulting physician or pharmacist (many preparations for coughs and colds contain adrenergic agents that affect the actions of rauwolfia alkaloids).

Common adverse effects in italic, life-threatening effects underlined; generic names in bold; classifications in SMALL CAPS; Canadian drug name; Prototype drug

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