What is Cypon Syrup?
Cypon syrup is a combination medication containing cyproheptadine hydrochloride (an antihistamine with antiserotonergic properties) and tricholine citrate, primarily marketed as an appetite stimulant, though the evidence for cyproheptadine's efficacy varies significantly by clinical context and underlying condition.
Composition and Mechanism
Each 5 mL of cyproheptadine syrup contains 2 mg of cyproheptadine hydrochloride 1. Cyproheptadine functions as both a serotonin and histamine antagonist with anticholinergic and sedative effects, competing with serotonin and histamine at their respective receptor sites 1.
Clinical Indications
Where Cyproheptadine Should NOT Be Used
In oncology patients with cancer-related anorexia and weight loss, cyproheptadine has limited evidence and reported adverse effects (level of evidence: C), and should only be used in randomized clinical trial settings 2. This guideline explicitly recommends corticosteroids and synthetic progestogens (megestrol acetate 160-480 mg/day or medroxyprogesterone acetate 200+ mg/day) as superior alternatives for appetite stimulation in cancer patients 2.
Similarly, patients with HIV and other malignant/progressive disease states show minimal to no benefit from cyproheptadine 3.
Where Cyproheptadine Shows Efficacy
Pediatric functional gastrointestinal disorders represent the strongest evidence base for cyproheptadine use:
- Functional abdominal pain and functional dyspepsia: 72.8% complete symptom improvement in children 4
- Irritable bowel syndrome: 100% improvement (10/10 patients) 4
- Cyclic vomiting syndrome: 75% improvement (6/8 patients) 4
- Abdominal migraine: 72% improvement (13/18 patients) 4
- Retching after Nissen fundoplication: 86% response rate 5
Early vomiting (within 1 hour of meals) responds better than late vomiting 5. Young children and females show better response rates 5.
Feeding intolerance in infants and young children (<3 years): 67% showed significant positive effects with resolution of vomiting or improved feeding tolerance, with an additional 28% showing possible improvement 6.
Dosing
Typical pediatric dosing ranges from 0.14 mg/kg/day, with mean doses of 4.85-5.34 mg/day 4. However, published studies show wide variation in starting doses (0.069 to 0.825 mg/kg/day) 6.
Key predictor of success: Higher body mass index correlates with better clinical improvement—each 1-unit BMI increase raises odds of improvement by 1.5-fold (P=0.01) 4. Conversely, lower body weight increases odds of poor response.
Contraindications (FDA Label)
Absolute contraindications 7:
- Newborns or premature infants
- Nursing mothers (higher risk in infants)
- Hypersensitivity to cyproheptadine
- Concurrent MAOI therapy
- Angle-closure glaucoma
- Stenosing peptic ulcer
- Symptomatic prostatic hypertrophy
- Bladder neck obstruction
- Pyloroduodenal obstruction
- Elderly, debilitated patients
Safety Profile
Common side effects are generally mild and well-tolerated:
- Sleepiness: 13-16% of patients 4, 5
- Weight gain: 10% (though often desired) 4
- Constipation: rare 6
- Irritability/behavioral changes: 6% 5
- Increased appetite: 5% 5
68-70% of patients report no adverse effects 4. Only 2.5% discontinue therapy due to side effects 5. Patients experiencing side effects are more likely to have poor therapeutic response (P=0.04) 5.
Metabolism and Elimination
After oral administration, 40% of radioactivity is excreted in urine with no unchanged drug detected in chronic users. The principal metabolite is a quaternary ammonium glucuronide conjugate. Elimination is diminished in renal insufficiency, requiring dose adjustment 1.
Clinical Pitfalls
- Do not use in cancer or HIV-related cachexia—use progestogens or corticosteroids instead 2
- Avoid in newborns/premature infants—absolute contraindication 7
- Monitor for sedation initially—most common side effect but usually transient
- Consider trial before invasive testing in infants with feeding issues 6
- Better response in younger children, females, higher BMI patients, and early vomiting 4, 5